Bone Mineral Density and Bone Turnover in Patients with Knee Osteoarthritis Compared with Generalized Osteoarthritis

The aim of this study was to investigate bone mineral density (BMD) and bone turnover in patients with primary knee osteoarthritis (KOA) and to compare them with generalized OA (GOA) and nonGOA patients. A total of 88 postmenopausal primary KOA patients were studied. OA was graded by using knee radiographs. BMD of the lumber spine, femur, and radius, and biochemical markers of bone turnover, pyridinoline (Pyr), deoxypyridinoline (Dpyr), CTx, and osteocalcin were compared among each grade. BMD was also compared with 88 normal controls who were age and weight-matched. In 88 KOA patients, 56 were divided into 28 GOA and 28 non-GOA groups by grading hand radiographs. BMD and biochemical markers were compared between GOA and non-GOA. KOA patients had higher BMD at several skeletal sites compared with age- and weight-matched normals. A significant difference of BMD between each grade was observed between grades 0–1 and 3 (0.774 ± 0.143 versus 0.940 ± 0.185 g/cm², P < 0.001), grades 2 and 3 (0.781 ± 0.125 versus 0.940 ± 0.185 g/cm², P < 0.01) in the spine, and between grades 0–1 and 3 (0.505 ± 0.100 versus 0.564 ± 0.127 g/cm², P < 0.05) in the trochanter. A significant difference of biochemical bone markers was observed between grades 0–1 and 3 (P < 0.05) and between grades 2 and 3 (P < 0.05) in Pyr and grades 0–1 and 3 (P < 0.05) and between grades 1 and 4 (P < 0.05) in Dpyr, but not in osteocalcin and CTx. GOA patients had higher BMD of the spine (0.902 ± 0.175 versus 0.747 ± 0.138 g/cm², P < 0.01), trochanter (0.535 ± 0.107 versus 0.480 ± 0.107 g/cm², P < 0.05), and one-third of the radius (0.526 ± 0.068 versus 0.472 ± 0.089 g/cm², P < 0.05) and had significantly higher biochemical markers in Pyr and Dpyr than non-GOA patients. It is concluded that KOA patients had higher BMD at several skeletal sites. Biochemical bone markers were influenced by some degree of cartilage damage in OA patients. This tendency was stronger in GOA patients than in non-GOA patients. Received: 12 February 1999 / Accepted: 2 November 1999     

Low Bone Density with Normal Bone Turnover in Ovariectomized and Streptozotocin-Induced Diabetic Rats

Diabetes and estrogen deficit are known causes of osteopenia, diabetes being associated with a low bone turnover and estrogen deficit with a high bone turnover. In the present work, we studied the effect of combined ovariectomy and diabetes on bone mineral content (BMC) and bone mineral density (BMD) and several bone markers in the rat. Four groups of rats were studied: control (C), ovariectomized (O), diabetic (D), and ovariectomized and diabetic (DO). Twelve weeks after starting the experiments, BMC and BMD of the first six lumbar vertebrae were measured; a bone formation marker (BGP) and a bone resorption marker (free collagen cross-links, PYD) were also analyzed. Diabetic rats showed diminished gain in bone mass, BMC (D: 0.417 ± 0.028 g, DO: 0.422 ± 0.020 g) and BMDs (D: 0.171 ± 0.006 g/cm², DO: 0.174 ± 0.006 g/cm²) both being significantly (P < 0.001) lower than those of control (C: BMC 0.727 ± 0.024 g and BMD 0.258 ± 0.004 g/cm²) and ovariectomized (O: BMC 0.640 ± 0.044 g and BMD 0.240 ± 0.009 g/cm²) groups. Moreover, the BMC and BMD of the C group were significantly (P < 0.05) higher than that of the O group. BGP and PYD levels were significantly (P < 0.01) higher in the O group (BGP: 138.2 ± 16.8 ng/ml, PYD: 270.2 ± 17.8 nM/mM) than those found in the control rats (BGP: 44.7 ± 4.8 ng/ml, PYD: 165.6 ± 12.5 nM/mM); the D group showed significantly (P < 0.01) lower values (BGP: 27.4 ± 14.6 ng/ml, PYD: 55.0 ± 7.4 nM/mM) than those of the control group. The DO group showed similar levels (BGP: 43.4 ± 5.1 ng/ml, PYD: 146.7 ± 14.6 nM/mM) to those found in the C group. Although bone marker levels in the O and D groups were in accordance with those expected in these situations, in the DO group the corresponding levels are apparently ``normal.' Also, the decrease of gain in bone mass observed after combining estrogen deficit and diabetes (DO group) did not seem to be more marked than that caused by diabetes alone. Received: 7 January 1997 / Accepted: 7 August 1997     

Bone Turnover and Insulin-like Growth Factor I Levels Increase After Improved Glycemic Control in Noninsulin-dependent Diabetes Mellitus

It is unclear whether both bone resorption and formation are affected by glycemic control, and contribute to diabetic osteopenia. In this study, 20 patients with noninsulin-dependent diabetes mellitus (12 men and 8 postmenopausal women) and 20 healthy control subjects (10 men and 10 postmenopausal women) were examined at baseline and 2 months. The diabetic patients showed an improvement of glycemic control (decreased HbA_1c) at the second measurement. Analysis of variance showed that there was no effect of gender on the variables that increased with improved glycemic control, and therefore results are presented for both male and female subjects. Baseline values of serum osteocalcin, a marker of formation, were significantly lower in diabetic patients compared with healthy subjects (2.5 ± 1.3 versus 4.4 ± 1.4 ng/ml; P= 0.0006), but markers of bone resorption [urinary pyridinoline (PYD), deoxypyridinoline (DPD)] did not differ. Improved glycemic control in diabetic patients resulted in increased values of PYD (P= 0.012), DPD (P= 0.049), serum osteocalcin (P= 0.001), and serum insulin-like growth factor I (IGF-I, P= 0.003), but no change in serum parathyroid hormone or 25-hydroxyvitamin D. In diabetic patients there were inverse correlations for the percent change from baseline to improved glycemic control for osteocalcin and HbA_1c (r =−0.53; P= 0.016) and glucose (r =−0.46; P= 0.050). These data suggest that improved glycemic control is accompanied by an increase in bone turnover for male and female diabetic patients, possibly mediated by increased levels of circulating IGF-I. Received: 8 August 1997 / Accepted: 20 January 1998     

Influence of High Impact Loading on Ultrasound Bone Measurements in Children: A Cross-Sectional Report

Evidence suggests that weight-bearing exercise during the growing years may enhance peak bone mass. The purpose of this study was to compare ultrasound bone measurements, serum alkaline phosphatase (S-ALP), serum osteocalcin (S-OC), and dietary calcium in highly active and normal healthy male children. Subjects were 33 elite and subelite male gymnasts and 40 normoactive controls matched for age (9.4 ± 1.1 years), height (133.9 ± 5.9 cm), and weight (30.1 ± 3.8 kg). Measurements of broadband ultrasound attenuation (dB/MHz) through the calcaneus (CBUA) and ultrasound velocity (m/s) through the calcaneus (CVOS), distal radius (RVOS), and proximal phalanx of the index finger (PVOS) were performed using a Contact Ultrasonic Bone Analyzer (CUBA Research). Gymnasts had significantly greater CVOS (P < 0.001), RVOS (P < 0.0001), and PVOS (P < 0.05). There were no differences in CBUA, S-ALP, or S-OC between groups. RVOS correlated significantly with dietary calcium intake in all subjects (P < 0.05) and training time in the gymnasts (P < 0.05). Though gymnasts had significantly greater calcium intakes than controls (P < 0.05), whose mean value was below the RDA, after controlling for calcium intake in the gymnasts alone, RVOS was still significantly correlated with training time (P < 0.05). These preliminary results suggest that the heavy musculoskeletal loading inherent in gymnastics training produces positive adaptive responses in the growing skeleton. Furthermore, ultrasound appears to provide a safe, noninvasive means of comparing the skeletal status of exercising and normal healthy children, whereas single samples of biochemical markers did not discriminate between the groups. Received: 2 May 1996 / Accepted: 10 December 1996     

Osteoporosis and Bone Mineral Metabolism Disorders in Cirrhotic Patients Referred for Orthotopic Liver Transplantation

The purpose of this study was to determine the prevalence of osteoporosis, to estimate the bone turnover and hormonal status, and to identify the factors associated with bone disease in patients with end-stage liver disease who were referred for orthotopic liver transplantation. A prospective study was performed on 58 cirrhotic patients (6 with primary biliary cirrhosis, 14 with alcoholic cirrhosis, and 38 with posthepatitic cirrhosis), who were referred for orthotopic liver transplantation. Patients, excluding those with primary biliary cirrhosis, were classified in Child-Pugh groups according to the severity of liver disease (class B [28 patients], class C [24 patients]). Biochemical parameters of bone mineral metabolism and standard liver function tests were measured in all patients. Additionally, serum osteocalcin, urinary hydroxyproline/creatinine ratio, serum intact parathyroid hormone, serum 25-hydroxyvitamin D, serum 1,25-dihydroxyvitamin D, folliclestimulating hormone, and luteinizing hormone levels were determined in patients and controls within the same age range. Plasma testosterone, sex hormone-binding globulin levels, and free testosterone index were obtained for all men included in the study. Bone mass of the lumbar spine and femur were measured by dual X-ray absorptiometry (DPX-L), and were expressed as a standard deviation of mean values (Z-score) from a sex and age-matched control group. Spinal X-rays were obtained to assess vertebral fractures. Osteoporosis was considered as a factor in spinal bone mineral density with a Z-score below 2 or at least one vertebral fracture. Twenty-five patients (43%) had osteoporosis, with lower bone mass measurements in the lumbar spine than in the femoral neck (P < 0.005). Alcoholic and Child-Pugh C patients showed the lowest femoral bone mineral density values. Cirrhotic patients showed lower osteocalcin levels than controls (14.3 ± 5.9 vs. 18.2 ± 8.1 ng/ml; P < 0.05) and showed increased urinary hydroxyproline (125.1 ± 51.5 vs. 107.9 ± 26.6 nM/mg creatinine; P < 0.05). Serum 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D and parathyroid hormone levels were significantly lower in cirrhotic patients than in controls (10.3 ± 9.1 vs. 23.1 ± 26.6 ng/ml; P= 0.000), (12.9 ± 9.1 vs. 48.3 ± 11.5 pg/ml; P= 0.000), (16.6 ± 9.2 vs. 27.9 ± 8.2 pg/ml; P= 0.000), with no differences between Child-Pugh groups. Alcoholic Child-Pugh C patients showed the lowest 25-hydroxyvitamin D serum values (4.5 ± 2.2 ng/ml; P < 0.05). Male patients had lower testosterone levels than controls (302.5 ± 229.4 vs. 556.7 ± 146.5 ng/dl; P= 0.000), with increased sex hormone-binding globulin values. Levels of testosterone and gonadotropin were related to Child-Pugh classification. No correlation was found between bone mass and hormonal values. A significant decrease in bone mass, particularly in the lumbar spine, is seen in end-stage cirrhotic patients. Reduced bone formation and significant disorders of bone mineral metabolism, such as vitamin D deficiency, reduced parathyroid hormone levels, and hypogonadism are involved. Moreover, severity and etiology of the liver disease are the main risk factors for developing bone loss and mineral metabolism disorders in patients referred for orthotopic liver transplantation. Received: 7 March 1996 / Accepted: 24 June 1996     

Acute Effects of Ethanol on Mineral Metabolism and Trabecular Bone in Sprague-Dawley Rats

In order to assess the effects of acute ethanol intoxication on bone, 45 female Sprague-Dawley rats were studied. Five rats were sacrificed at baseline. The remainder received either ethanol (2 g/kg of body weight) intraperitoneally or isotonic saline. Rats were sacrificed in groups of 10 (5 intoxicated and 5 placebo) at 1, 4, 8, and 24 hours after injection. At the time of sacrifice, a blood sample was obtained and the 4th vertebra was excised for histomorphometric analysis of undecalcified bone. Effect of ethanol was assessed by an analysis of variance test using a Scheffé procedure. In ethanol-treated rats we observed (mean ± SD, ethanol versus controls, maximum difference point, P value) a significant decrease in osteiod surface with osteoblasts (42.86 ± 15.61% versus 64.57 ± 6.24%, P < 0.05); osteoclast number (0.05 ± 0.02 n/mm² versus 0.17 ± 0.09 n/nm², P < 0.05), and osteocalcin (36.9 ± 2.21 ng/ml versus 45.8 ± 5.1 ng/ml, P < 0.05). Osteoclast surface was initially reduced (0.129 ± 0.09% versus 0.425 ± 0.26%, P < 0.01) but showed a subsequent increase (0.765 ± 0.24% versus 0.226 ± 0.17%, P < 0.01) attributable to alcohol. There was also a significant decrease in serum Ca (8.51 ± 0.23 mg/dl versus 9.10 ± 0.29 mg/dl, P < 0.01) and parathyroid hormone values (23.51 ± 5.72 pg/ml versus 76.39 ± 11.66 pg/ml, P < 0.001). We conclude that acute alcohol intoxication in rats induces early striking changes in bone histology and analytical parameters, not completely reversed after 24 hours. These data are consistent with a toxic effect induced by alcohol on bone. Received 30 May 1996 / 31 December 1996     

Higher Osteocalcin Levels and Cross-Links Excretion in Young Men Born with Low Birth Weight

As the result of accelerated growth, the final height of infants born with low birth weight (LBW) is near to the normal. Limited data are available about the bone density and bone turnover just after completion of skeletal development. We have investigated the bone turnover and bone density in 49 apparently healthy young LBW men (age 19–21 years; 21 born small for gestational age (SGA) and 28 appropriate for gestational age (AGA)) and in 16 age-matched controls. Bone mineral density of lumbar spine, femoral neck, and radius midshaft, the markers of calcium homeostasis, biochemical parameters of bone turnover as serum osteocalcin (OC), and urinary pyridinoline (PYD) and deoxypyridinoline (DPD) levels were measured. Bone mineral densities of LBW subjects were not altered. Serum calcium (SGA: 2.44 ± 0.15; AGA:2.41 ± 0.17, control: 2.25 ± 0.09 mmol/liter, P < 0.05), OC (SGA:23.4 ± 9.9; AGA:20.8 ± 7.6; control:13.3 ± 4.6 ng/ml, P < 0.01), total alkaline phosphatase (AP) (SGA:201 ± 61; AGA:193 ± 81, control:117 ± 34 IU/liter, P < 0.01), and urinary DPD/creat (ln.values: SGA:3.10 ± 0.48; AGA:3.17 ± 0.46; control:2.58 ± 0.57 nmol/mmol, P < 0.05) were higher, whereas fractional excretion of calcium (SGA:0.94 ± 0.470; AGA:1.03 ± 0.51, control:1.31 ± 0.75%, P < 0.05) was lower in both SGA and AGA groups. PTH and 25OHD were not different. Significant correlation was obtained between seCa, OC, AP, DPD and birth weight of the subjects, but feCa correlated inversely to the birth weight. It was concluded that the bone turnover of LBW men is accelerated, but well balanced in young adulthood. Further investigation is needed to describe the possible link between accelerated bone turnover and hormonal homeostasis of LBW subjects. Received: 30 November 1999 / Accepted: 9 September 2000 / Online publication: 22 December 2000     

Osteogenesis Imperfecta: Bone Turnover, Bone Density, and Ultrasound Parameters

We studied 21 patients (11 men and 10 women) with osteogenesis imperfecta (OI) and 21 age- and sex-matched controls. In all patients we measured serum levels of total alkaline phosphatase (ALP), type I procollagen carboxy-terminal propeptide (PICP), osteocalcin (BGP), urinary excretion of hydroxyproline (HOP/Cr), and pyridinoline crosslinks (Pyr/Cr). Bone mineral density was measured at the distal radius (BMD-R) and at the lumbar spine (BMD-LS) by dual X-ray absorptiometry (DXA). Ultrasound parameters were also performed at the calcaneous with the Achilles device and at the phalanxes with DBM Sonic 1200. A significant reduction (P < 0.001) in BMD and in ultrasound parameters was found in OI patients compared with normals. PICP was significantly reduced in the OI patients compared with controls (P < 0.001); other markers of bone turnover were higher in OI than in controls, but the difference did not reach the statistical significance. A significant correlation (P < 0.05) was found between PICP and BMD at the lumbar spine and between PICP and ultrasound parameters at the calcaneous. On the basis of our data, we conclude that patients with OI show low values of BMD and ultrasound parameters; therefore in these patients, not only is bone mass disturbed but also bone quality. The reduced levels of PICP in OI patients confirm that most OI patients have defects in collagen I biosynthesis. These defects may contribute to the fragility of OI bone by interfering with complete mineralization and/or normal tissue structure. PICP may be considered a useful marker in the clinical management of OI. Received: 26 March 1998 / Accepted: 15 January 1999     

Differences in Bone Turnover and Skeletal Response to Thyroid Hormone Treatment Between Estrogen-Depleted and Repleted Rats

This study was undertaken to compare the effect of supraphysiological doses of thyroxine (T4) on bone metabolism in SHAM and OVX young adult rats. Female Sprague Dawley rats (220 ± 2 g, approx. 5 months of age) were divided into four groups of eight animals each. The animals were intraperitoneally injected 6 days per week with vehicle (Vh): 0.001 N NaOH/0.9% NaCl (SHAM+Vh and OVX+Vh) or 250 μg of thyroxine/kg/day (SHAM+T4 and OVX+T4) during a 5-week period. Serum T4 and osteocalcin (BGP), urinary pyridinolines (Pyr), and creatinine (creat) were determined. At the beginning and at end of the experiment, skeletal bone mineral content (BMC), bone mineral density (BMD), and area (A) of the total skeleton, femur, spine, and whole tibia, as well as proximal, middle, and distal areas of the tibia were assessed by dual X-ray absorptiometry (DXA) in an ultra-high-resolution mode. T4 treatment of the SHAM rats did not induce significant changes in BGP level or Pyr/creat excretion compared with the SHAM+Vh control group. However, these two biochemical bone markers significantly increased due to T4 treatment in OVX rats compared with both OVX+Vh and SHAM+T4 groups (P < 0.05 and P < 0.001, respectively). The OVX+T4 group had a significantly lower ΔBMD than SHAM+T4 rats in all studied regions (P < 0.05) except for the middle tibia region. OVX+T4 groups presented a significantly lower ΔBMC and ΔA compared with SHAM+T4 animals (P < 0.001). OVX+T4 rats significantly impaired the ΔBMD in the femur (P < 0.01), spine (P < 0.05), whole (P < 0.05) and middle (P < 0.05) tibia whereas T4 treatment of SHAM rats only affected, significantly, the whole (P < 0.05) and the proximal tibia region (P < 0.01). T4 treatment affects bone growth in young adult rats. The effect is significantly greater in the estrogen-depleted than in the estrogen-repleted state. The bone site most adversely affected by T4 treatment depends on the estrogen status. The proximal tibia (principally trabecular bone) was the most affected area in estrogen-repleted rats. Conversely, in OVX rats, the middle tibia (principally cortical bone) presented the greatest decrease in bone density. Received: 20 May 1999 / Accepted: 4 February 2000     

Elevated Collagen Turnover in Nigerian Children with Calcium-Deficiency Rickets

Calcium deficiency is a major etiological determinant of rickets in Nigerian children and is accompanied by undermineralization of the developing bone matrix which is composed largely of type I collagen. We have assessed types I and III collagen metabolism by measuring the circulating concentrations of the N- and C-terminal propeptides (intact PINP and PICP) and the C-terminal telopeptide (ICTP) of type I collagen, and the N-terminal propeptide (PIIINP) of type III collagen in 94 healthy Nigerian children and in 44 children aged 1–5 years with active calcium-deficiency rickets. In active rickets the mean levels of the four collagen metabolites were approximately twofold higher than in the healthy children, despite a wide variation of individual values. Mean intact PINP was 812 ± 279 versus 403 ± 189 μg/liter; PICP was 573 ± 265 versus 348 ± 229 μg/liter; PIIINP was 16.8 ± 8.6 versus 10.8 ± 3.6 μg/liter, and ICTP was 28.4 ± 17.2 versus 11.9 ± 4.1 μg/liter (all P < 0.001), in rachitic and healthy children, respectively. Healthy children younger than 3 years had higher levels of all the collagen metabolites than those between 3 and 5 years (all P < 0.05). Alkaline phosphatase was greater in rickets than in the healthy group (P < 0.001) whereas mean osteocalcin levels were slightly lower (P= 0.09). 1,25(OH)₂D correlated with all the collagen propeptides, but not with ICTP in the healthy children. No such correlations were found in rickets, where there was a poor inverse correlation between 1,25(OH)₂D and ICTP. These data suggest that collagen turnover is elevated in cases of calcium-deficiency rickets, where vitamin D status is adequate, possibly indicating increased turnover of undermineralized osteoid. Received: 15 October 1996 / Accepted: 5 March 1997     

Decreased Estradiol Levels and Free Androgen Index and Elevated Sex Hormone-Binding Globulin Levels in Male Idiopathic Osteoporosis

Estrogen deficiency is an important pathogenetic factor in female osteoporosis, and androgens are known to have anabolic effects on bone. In this study we have compared 12 men with idiopathic osteoporosis, age 27–55 years, with 12 age-matched men, with respect to serum levels of sex steroids, biochemical markers of bone turnover, bone density, and body composition. All subjects showed values within the normal range for all hormonal parameters. The patient group compared with the controls had significantly lower serum levels of estradiol (71 ± 13 versus 85 ± 14 pmol/liter, P < 0.03); estradiol/sex hormone-binding globulin (SHBG) ratio (22.4 ± 12.1 versus 39.5 ± 18.6 pmol/mg, P < 0.02); free androgen index (51.0 ± 19.4 versus 74.1 ± 33.1%, P < 0.05); and higher SHBG (3.7 ± 1.6 versus 2.5 ± 1.0 mg/liter; P < 0.04). The men with idiopathic osteoporosis had significantly lower body mass index (23.2 ± 2.8 versus 25.9 ± 3.3 kg/m², P < 0.05); and a tendency to lower percentage of total body fat (14.2 ± 5.5 versus 18.6 ± 6.0%; P < 0.10) than the controls. Regression analyses revealed that bone mineral density in femoral neck correlated significantly and positively with the ratio estradiol/SHBG (r = 0.67; P < 0.04) and negatively with SHBG concentrations (r =−0.63; P < 0.04) in the group of patients. These findings could represent a pathogenetic mechanism in male idiopathic osteoporosis. Received: 19 March 1998 / Accepted: 24 June 1998     

Ultrasound and X-ray-Based Bone Densitometry in Patients with Anorexia Nervosa

In 20 patients (mean age 23 ± 5 years) with anorexia nervosa (AN), bone mass was evaluated by broadband ultrasound attenuation (BUA) of the calcaneus, peripheral quantitative computed tomography (pQCT) of the distal radius, and dual X-ray absorptiometry (DXA) of the lumbar spine and the hip. Compared with 20 age- and sex- matched healthy controls, patients with AN showed marked osteopenia at all measuring sites. Values of BUA (33.0 ± 9dB/MHz vs. 51.0 ± 5.7 dB/MHz; P < 0.0001) and of BMD of all regions of the hip (e.g., femoral neck: 0.71 ± 0.13 g/cm² versus 0.89 ± 0.07 g/cm²; P < 0.001), lumbar spine (0.82 ± 0.15 g/cm² versus 1.24 ± 0.06 g/cm²; P < 0.003) and total BMD of the peripheral radius (303.2 ± 75 g/cm³ versus 369.4 ± 53.2 g/cm³, P < 0.001) were significantly reduced. Calculating a Z-score we found the most prominent differences between AN and controls by BUA of the calcaneus (−3.2 ± 1.6), followed by DXA at the lumbar spine (−2.9 ± 2.2) and the hip (femoral neck −2.1 ± 1.7) and by pQCT at the distal radius (total BMD −1.2 ± 2.0). There were highly significant correlations between BUA of the calcaneus and BMD of the femoral neck (r = 0.78, P < 0.0001) and lumbar spine (r = 0.75, P < 0.0001) as well as between BMD values of the femoral neck and lumbar spine (r = 0.95; P < 0.0001). In addition, there were significant correlations (P < 0.001) between body mass index (BMI) and the three different measuring sites and between the duration of the disease and BUA (r = 0.5, P < 0.05). Our data suggest that BUA of the calcaneus is a valuable tool in the management of osteoporosis. Being a fast, radiation-free investigation method of good acceptance, it may be well suited for an assessment of the skeletal status in patients with AN. Received: 14 October 1998 / Accepted: 10 December 1999     

Increased Serum 1,25-Dihydroxyvitamin D after Growth Hormone Administration is not Parathyroid Hormone-Mediated

To assess the effects of growth hormone (GH) on serum 1,25-dihydroxyvitamin D [1,25(OH)₂D], we performed the following prospective crossover study in six healthy, young, adult, white men. During each of two admissions for 2? days to a general clinical research center, subjects were placed on a daily dietary calcium intake of 400 mg. Serum calcium, phosphorus, 1,25(OH)₂D, immunoreactive intact parathyroid hormone (PTH), insulin-like growth factor I (IGF-I), IGF binding protein 3 (IGFBP3), tubular reabsorption of phosphate (TRP), and maximum tubular reabsorption of phosphate (TMP/GFR) were measured. Recombinant human GH (rhGH, Humatrope) (25 μg/kg/day subcutaneously for 1 week) was administered prior to and during one of the admissions. Results are expressed as mean ± SEM. Whereas serum 1,25(OH)₂D (58.9 ± 7.7 versus 51.6 ± 7.4 pg/ml, P < 0.01), serum phosphorus (4.5 ± 0.1 versus 3.7 ± 0.1 mg/dl, P < 0.01), TRP (92.0 ± 0.5 versus 87.8 ± 0.7 mg/dl, P < 0.005), TMP/GFR (4.6 ± 0.1 versus 3.5 ± 0.2, P < 0.005), and urinary calcium (602 ± 49 versus 346 ± 25 mg/day, P < 0.001) increased significantly, serum PTH decreased significantly (19.9 ± 1.9 versus 26.8 ± 4.0 pg/ml, P < 0.05) and serum calcium did not change when subjects received rhGH. These findings indicate that in humans, GH affects serum 1,25(OH)₂D independently of circulating PTH and that this effect is mediated by IGF-I. We propose, therefore, that one potential mechanism by which GH stimulates increases in bone mass is via modest increases in serum 1,25(OH)₂D. Received: 2 May 1996 / Accepted: 18 October 1996     

Androgen-Receptor Blockade Does Not Impair Bone Mineral Density in Adolescent Females

The effect of peripheral androgen hypersensitivity on bone mineral density (BMD) was investigated in a group of adolescent women with idiopathic hirsutism (n= 17; mean age 17.0 ± 1.7 years). The effect of long-term androgen-receptor blockade with flutamide (500 mg daily in two divided doses for 12 months) on BMD was assessed too. BMD was measured at lumbar spine (L2–L4) by a dual energy X-ray densitometer. Before flutamide treatment, patient BMD (1.14 ± 0.07 g/cm²) was not significantly different from that of the control group (1.16 ± 0.12 g/cm², n= 22), and was normal for age and sex (BMD 0.14 ± 0.69 SDS, P= NS vs. 0). After 12 months of treatment, absolute BMD in patients increased (1.18 ± 0.08 g/cm², P < 0.002), but SDS BMD did not change (0.21 ± 0.72, P= NS vs. baseline). Flutamide treatment determined a clinical, marked improvement of androgen hypersensitivity (Ferriman–Gallwey score: before 22.0 ± 6.2; 6 months: 13.2 ± 6.4, P < 0.003; 12 months; 7.6 ± 4.1, P < 0.001; acne score: before 3.8 ± 0.8; 3 months 0.8 ± 0.5, P < 0.001; later disappeared). The serum levels of 3α-androstenediol-glucoronide decreased (before: 8.6 ± 1.1 μg/liter; 12 months: 7.2 ± 1.0 μg/liter, P < 0.02), whereas the other endocrinological parameters did not change. No relationship was found between BMD and clinical or biochemical parameters of hyperandrogenism. We concluded that in adolescent women, peripheral hyperandrogenism is not associated with abnormal BMD; long-term treatment with flutamide, which blocks the androgen receptor, does not alter their BMD. Received: 19 February 96 / Accepted: 31 December 96     

Genetic Variation and Covariation of Parathyroid Hormone Levels and Bone Density in the Human Population

The present study was an attempt to evaluate the relative importance of familial/genetic factors in interindividual variation of plasma concentrations of parathyroid hormone (PTH) and bone mineral density (BMD). We also examined to what extent common genetic and environmental factors may be involved in covariation between the hormone concentrations and BMD levels. Ninety-five nuclear pedigrees (consisting of 187 males and 168 females, aged 18–91 and 18–86 years old, respectively), from several small villages in the Chuvasha Autonomy, Russia, were assessed for PTH, sex hormones, and BMD. PTH plasma levels were measured in duplicate by immunoradiometric assay using an N-tact PTH SP kit. Standard roentgenography was done from the second and third phalanges of the middle finger on both hands for assessment of compact and cancellous bone BMD separately. The present study clearly confirmed the results of the previous genetic analyses of BMD which indicated that between 47% and 60% of the total variance of BMD, adjusted for sex and age effects, were attributable to genetic factors. Genetic factors also contributed significantly to interindividual variation of PTH. Constraining these additive genetic effects to zero dramatically increased the likelihood ratio (P < 0.001), indicating that at least 30% of the hormone plasma variation was attributable to genetic sources. The results of bivariate decomposition analysis were not clear cut. Two types of bivariate analyses showed that PTH-BMD genetic correlations according to sex and between the opposite sexes were consistently negative, but only marginally significant. Received: 21 July 1998 / Accepted: 30 September 1999     

The Effect of Intermittent Slow-Release Sodium Fluoride and Continuous Calcium Citrate Therapy on Calcitropic Hormones, Biochemical Markers of Bone Metabolism, and Blood Chemistry in Postmenopausal Osteoporosis

A detailed examination of calcitropic hormones and biochemical markers of bone turnover, serum chemistry, and blood hematology was performed in 75 postmenopausal women allocated to two groups: placebo plus calcium citrate (400 mg Ca B.I.D.) (n = 36) or intermittent slow-release sodium fluoride (SRNaF, 25 mg B.I.D.) plus calcium citrate (n = 39). After 2 years of therapy, a significant reduction in serum immunoreactive parathyroid hormone (PTH) was seen for both groups (43 ± 18 SD–30 ± 11 ng/liter, in placebo and 46 ± 24–36 ± 10, in SRNaF P < 0.0001 for both groups). Serum 1,25(OH)₂D significantly fell in placebo-treated patients (91 ± 31–75 ± 34 pmol/liter, P= 0.001) but did not change for SRNaF-treated patients. This difference in response between placebo and SRNaF-treated groups was significant, P= 0.005. Urinary hydroxyproline significantly declined during treatment in both groups (130 ± 61–76 ± 38 μmol/day, for placebo and 138 ± 84–84 ± 38 for SRNaF, P= 0.001). Similar decreases in urinary N-telopeptide of type I collagen were also observed for both groups (305 ± 192–252 ± 197 nmoles BCE/day for placebo and 356 ± 230–220 ± 197, P= 0.0001 for SRNaF). Serum carboxyterminal propeptide of type I collagen (PICP) declined significantly in both the placebo and SRNaF groups (118 ± 38–101 ± 36 μg/liter, and 116 ± 47–105 ± 39, P= 0.0027). Serum osteocalcin did not change significantly for either group, but bone-specific alkaline phosphatase (BS-ALPase), another marker of bone formation, demonstrated a significant fall in the placebo group at 2 years of therapy (16.2 ± 6.7 U/liter–12.1 ± 3.5, P= 0.009) and a small increase in the SRNaF-treated patients (13.0 ± 4.1–15.0 ± 4.5). The observed difference in response of BS-ALPase between the placebo and treated groups was significant (P= 0.007). There were no significant changes within or between treatment groups for blood hematology or serum chemistries. Mean values for all parameters remained within established normal ranges. These findings suggest that administration of calcium citrate inhibited PTH secretion and thereby reduced bone resorption in both groups, indicated by a decline in serum PTH, urinary hydroxyproline, and N-telopeptide. A low turnover state of bone may have been produced in the placebo group taking calcium citrate alone, since serum PICP, BS-ALPase, and 1,25(OH)₂D also decreased. The addition of SRNaF prevented serum 1,25(OH)₂D from falling by an unknown mechanism. However, its anabolic action on the skeleton was best reflected by changes in BS-ALPase. Moreover, SRNaF appeared to exert no deleterious effects on blood chemistries or hematology during 2 years of administration. Received: 28 January 1996 / Accepted: 25 April 1997     

Skeletal Response to Dietary Zinc in Adult Female Mice

The current studies were intended to assess dose- and time-dependent effects of dietary zinc (Zn) on alkaline phosphatase (ALP) activity and tartrate-resistant acid phosphatase (TRAP) activity in adult female mice. In the first study, mice were given 0, 1×, 2×, 3×, or 4× normal dietary Zn for 2 weeks, 4 weeks, or 6 weeks. In the second study, mice were given 0, 1×, 2×, 3×, 4×, and 5× normal dietary Zn for 4 weeks. Sera were collected for measurements of ALP and (in the second study) osteocalcin. Tibiae and calvaria were extracted for measurements of ALP, protein, and TRAP. The first study showed positive correlations between dietary Zn and serum ALP (4 and 6 weeks, P < 0.001), Zn and tibial ALP (2, 4, and 6 weeks, P < 0.03), and Zn and tibial protein (2, 4, and 6 weeks, P < 0.001), as well as a negative correlation between dietary Zn and tibial TRAP (2, 4, and 6 weeks, P < 0.001). Covariant analyses showed that serum ALP, tibial ALP, tibial protein, and tibial TRAP were affected by the dose of Zn (P < 0.005) and by the treatment time (P < 0.03). Supplemental studies showed that (1) the dose-dependent effect of dietary Zn on serum ALP (at 6 weeks) was proportional to the effects on tibial ALP and calvarial ALP, but not to the effects of Zn on renal, hepatic, or intestinal ALP; (2) 6 weeks of dietary Zn caused dose-dependent increases in ALP specific activity in the tibia, calvaria, and liver, but not kidneys or intestines; and (3) Zn increased ALP activity and cell layer protein and decreased TRAP activity in monolayer cultures of the murine osteoblastic cell line, MC3T3-E1. The second dietary study confirmed the results of the first: 4 weeks of treatment with Zn caused significant increases in serum ALP, calvarial ALP, and tibial ALP activities, and a significant decrease in tibial TRAP (P < 0.05–0.005 for each). This study also revealed an effect of Zn to increase serum osteocalcin (P < 0.03 at 2× normal Zn). Together, these data indicate that incremental increases in dietary Zn are associated with increases in ALP activity in serum and in bone. The effect of Zn to decrease TRAP activity in osteoblast-line cells precludes the interpretation of a Zn-dependent decrease in tibial TRAP activity as evidence of decreased bone resorption.     

Bone Mineral Content and Density in Professional Tennis Players

Total and regional bone mineral content (BMC) as well as lean and fat mass were measured in nine male professional tennis players (TPs) and 17 nonactive subjects; dual-energy X-ray absorptiometry (DXA) was used for measuring. The mean (±SD) age, body mass, and height were 26 ± 6 and 24 ± 3 years, 77 ± 10 and 74 ± 9 kg, and 180 ± 6 and 178 ± 6 cm for the TP and the control group (CG), respectively. The whole body composition for BMC, lean mass, and fat of the TP was similar to that observed in the CG. The tissue composition of the arms and legs was determined from the regional analysis of the whole-body DXA scan. The arm region included the hand, forearm, and arm, and was separated from the trunk by an inclined line crossing the scapulo-humeral joint. In the TP, the arm tissue mass (BMC + fat + lean mass) was about 20% greater in the dominant compared with the contralateral arm because of a greater lean (3772 ± 500 versus 3148 ± 380 g, P < 0.001) and BMC (229.0 ± 43.5 versus 188.2 ± 31.9 g, P < 0.001). In contrast, no significant differences were observed either in BMC or BMD between arms in the CG. Total mass, lean mass, and BMC were greater in the dominant arm of the TP than in the CG (all P < 0.05). In the TP, BMD was similar in both legs whereas in the CG, BMD was greater in the right leg. Lumbar spine (L2–L4) BMD, adjusted for body mass and height, was 15% greater in the TP than in the CG (P < 0.05). Femoral neck BMDs (femoral neck, Ward's triangle, greater trochanter, and intertrochanteric regions) adjusted for body mass and height were 10–15% greater in the TP (all P < 0.05). Ward's triangle BMD was correlated with the maximal leg extension isometric strength (r = 0.77, P < 0.05) even when adjusted for body mass (r = 0.76, P < 0.05) and height (r = 0.77, P < 0.05). In summary, the participation in tennis is associated with increased BMD in the lumbar spine and femoral neck. These results may have implications for devising exercise strategies in young and middle-aged persons to prevent involutional osteoporosis later in life. Received: 29 April 1997 / Accepted: 14 November 1997     

Net Fluxes Over Working Thigh of Hormones,Growth Factors and Biomarkers of Bone Metabolism During Short Lasting Dynamic Exercise

The purpose of this study was to evaluate the responses of hormones, growth factors, and biomarkers involved in bone and muscle metabolism during exercise and in recovery. One leg knee-extension exercise and concomitant sampling from the artery and vein were performed. In 12 healthy individuals (6 men and 6 women; age 21–36 years) blood was drawn from the femoral artery and vein at rest, after 10 minutes warm-up, after 15 minutes work at 61% of peak one leg VO₂, and after 5 minutes work at peak one leg VO₂, as well as 5, 30, and 60 minutes in recovery. Blood flow in the femoral vein was measured using the thermodilution technique. Arteriovenous differences were measured over working thigh for growth hormone (GH), insulin-like growth factor I (IGF-I), insulin-like growth factor binding protein 3 (IGF BP3), parathyroid hormone (PTH) and bone biomarkers, i.e., the carboxyterminal propeptide of type I procollagen (PICP), the carboxyterminal cross-linked telopeptide of type I collagen (ICTP), osteocalcin, and bone-specific alkaline phosphatase (b-ALP). There was an uptake of GH (3.1 ± 1.2 mU · min⁻¹, P < 0.001; mean ± SE) over thigh during exercise and a release of IGF-I at the end of exercise (60 ± 36 μg · min⁻¹; P < 0.01). PICP was also released after the maximal exercise (23 ± 12 μg · min⁻¹; P < 0.01) as well as ICTP (0.5 ± 0.3 μg · min⁻¹; P < 0.05) and b-ALP (0.2 ± 0.1 μkat · min⁻¹; P < 0.05). Osteocalcin, IGF BP3, and PTH revealed no clearcut pattern. In the present study, exercise induces endocrine changes which point to anabolic effects on muscle and bone tissue. Received: 12 February 1996 / Accepted: 6 June 1996     

Biochemical Markers of Bone Turnover Reflect Femoral Bone Loss in Elderly Women

Although over 90% of hip fractures occur in patients over age 70, few data are available on femoral bone loss in this age group. To examine the relationship between biochemical markers of bone turnover and femoral bone loss in the elderly, 36 female and 17 male, healthy, community-dwelling elderly over age 65 (mean ± SD age: women 71 ± 4 years, men 75 ± 5 years) were followed for 3 years. Annual bone mineral density measurements of the hip and lumbar spine by dual-energy x-ray absorptiometry (DXA) were obtained and biochemical markers of bone resorption (urinary N-telopeptide crosslinks, free pyridinoline, total pyridinoline, total deoxypyridinoline, and hydroxyproline) and bone formation (serum osteocalcin, bone-specific alkaline phosphatase) were obtained at the end of year 3. In elderly women, longitudinal bone loss at the total hip was negatively correlated with markers of bone resorption (r =−0.39 to −0.52, P < 0.05), bone formation (r =−0.38, P < 0.05), and age (r =−0.39, P < 0.05). Markers of bone resorption were correlated with markers of bone formation (r = 0.63 to 0.74, P < 0.01). In multiple regression analysis, urinary N-telopeptide crosslinks (marker of resorption), serum osteocalcin (marker of formation), and serum parathyroid hormone explained 43% of the variability of bone loss at the total hip in women. These parameters were not related to bone loss in men. We conclude that femoral bone loss increases with age in women over 65. Measurements of specific biochemical markers of bone turnover are correlated with longitudinal bone loss in elderly women. These markers may help identify women at greatest risk for bone loss who would benefit most from therapeutic interventions. Received: 28 January 1996 / Accepted: 3 May 1996