Resolution of vitamin D insufficiency in osteopenic patients results in rapid recovery of bone mineral density.

Vitamin D insufficiency is characterized biochemically by the presence of secondary hyperparathyroidism, which can contribute to bone loss in osteopenic patients. Over a 2-yr period of evaluation of 118 consecutive, free living patients with osteopenia or osteoporosis, we identified 18 subjects with depressed serum 25-hydroxyvitamin D (250HD; < or = 14 ng/mL). Twelve of these subjects harbored a low 25OHD level and consented to undergo replacement with 50,000 IU vitamin D2 twice weekly for 5 weeks. Five hundred thousand units of oral vitamin D2 resulted in significant increases in 25OHD (+24.3+/-16.9 ng/mL; P < 0.001) and the fasting urinary calcium/creatinine excretion ratio (+0.06+/-0.004; P = 0.01) and significant decreases in the serum concentration of PTH (-32.9+/-36.9 pg/mL; P < 0.001) and osteocalcin (-4.9+/-2.4 ng/mL; P < 0.001). Vitamin D repletion was associated with a significant 4-5% annualized increase in bone mineral density at both the lumbar spine (P < 0.001) and the femoral neck (P = 0.03), indicating that resolution of vitamin D insufficiency in a population of patients with low bone mass results in a rapid rebound increase in bone mineral density.     

The effect of 1,25(OH)2D3 on bone mineral content in senile osteoporosis--a dose-finding study

In order to clarify the effect of 1,25(OH)2D3 on the bone mineral content in senile osteoporosis, we examined the radial mineral density in 41 female cases of senile osteoporosis treated with 1,25(OH)2D3. The diagnostic criteria of senile osteoporosis were as follows. 1) Radial mineral density at below 0.5 g/cm2 by SPA 2) Bone dystrophy score in vertebra at over I degree 3) Presence of vertebral fracture 4) Over 60 years of age The subjects were divided into 5 groups: a control group (n = 11), a 0.25 microgram of 1,25(OH)2D3 once-a-day group (n = 5), a 0.5 microgram of 1,25(OH)2D3 once-a-day group (n = 8), a 0.25 microgram of 1,25(OH)2D3 twice-a-day group (n = 8) and a 0.25 microgram of 1,25(OH)2D3 three times-a-day group (n = 9). There was no significant difference in background data among these groups except for serum Al-P activity. The radial mineral density was measured in these 5 groups before and every 3 months after, starting the treatment by single photon absorptiometry in 1/3 distal site of radius for 1 year. No significant difference was detected in the serum levels of Ca, Pi and Al-P activity after starting the treatment among the 5 groups. The area under curve (AUC) of the radial mineral content after the treatment was calculated in each group. There was a significant dose-related increase in the AUC (p less than 0.05). However, the urinary Ca/Cr ratio was increased in the group receiving 0.75 microgram/day of 1,25(OH)2D3 The final AUC in the group receiving 0.5 microgram/day of 1,25(OH)2D3 tended to be very high compared with that in the other groups. From the above, it was suggested that 1,25(OH)2D3 might be effective for the treatment of senile osteoporosis especially at the dose of 0.5 microgram/day.     

Effect of vitamin D2 and vitamin D3 on the serum concentrations of 1,25(OH)2D2, and 1,25(OH)2D3 in normal subjects

Serum concentrations of vitamin D2 and vitamin D3 metabolites were measured in 19 normal subjects before and during treatment with either vitamin D2 or vitamin D3, 4000 IU per day for 8 weeks. Vitamin D2 treatment increased the serum concentration of 1,25(OH)2D2, but a corresponding decrease in 1,25(OH)2D3 resulted in an unchanged serum concentration of total 1,25(OH)2D. During treatment with vitamin D3, the serum concentration of 1,25(OH)2D metabolites was unchanged. We conclude that the production of 1,25(OH)2D is tightly regulated and that 1 alpha-hydroxylase does not discriminate between D2 and D3 metabolites in normal subjects.     

Effects of 1,25(OH)2D3 on bone mineralization in vitamin D deficiency (author's transl)]

Two cases with vitamin D-deficient osteomalacia of digestive origin (coeliac disease) have been treated orally with 1,25(OH)2D3 in dosages of respectively 8 and 3 microgram/24 h. Serial transiliac bone biopsies have been performed. Mineralization fronts were normalized after respectively 4 and 1.5 months, whereas mineralization rates, as demonstrated by double tetracycline labeling, were normalized respectively after 2 and 1.5 months. In both cases osteomalacia healed completely despite persistently low 25(OH)D levels in the serum. It is obvious from these studies that 1,25(OH)2D3 per se is able to cure vitamin D-deficient osteomalacia, a finding that has been disputed. Whether 25(OH)D acts more rapidly on bone, as suggested by the studies performed in one case with anticonvulsant osteomalacia, remains to be proven.     

Effect of 24,25-dihydroxyvitamin D3 on 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] metabolism in vitamin D-deficient rats infused with 1,25-(OH)2D3

Previous studies revealed that administration of 24,25-dihydroxyvitamin D3 [24,25-(OH)2D3] to calcium (Ca)-deficient rats causes a dose-dependent reduction in markedly elevated serum 1,25-(OH)2D3 level. Although the results suggested that the metabolism of 1,25-(OH)2D3 was accelerated by 24,25-(OH)2D3, those experiments could not define whether the enhanced metabolism of 1,25-(OH)2D3 played a role in the reduction in the serum 1,25-(OH)2D3 level. In the present study, in order to address this issue more specifically, serum 1,25-(OH)2D3 was maintained solely by exogenous administration through miniosmotic pumps of 1,25-(OH)2D3 into vitamin D-deficient rats. Thus, by measuring the serum 1,25-(OH)2D3 concentration, the effect of 24,25-(OH)2D3 on the MCR of 1,25-(OH)2D3 could be examined. Administration of 24,25-(OH)2D3 caused a dose-dependent enhancement in the MCR of 1,25-(OH)2D3, and 1 microgram/100 g rat.day 24,25-(OH)2D3, which elevated serum 24,25-(OH)2D3 to 8.6 +/- 1.3 ng/ml, significantly increased MCR and suppressed serum levels of 1,25-(OH)2D3. The effect of 24,25-(OH)2D3 on 1,25-(OH)2D3 metabolism developed with a rapid time course, and the recovery of iv injected [1 beta-3H]1,25-(OH)2D3 in blood was significantly reduced within 1 h. In addition, there was an increase in radioactivity in the water-soluble fraction of serum as well as in urine, suggesting that 1,25-(OH)2D3 is rapidly degraded to a water-soluble metabolite(s). Furthermore, the reduction in serum 1,25-(OH)2D3 was associated with a reduction in both serum and urinary Ca levels. Because the conversion of [3H]24,25-(OH)2D3 to [3H]1,24,25-(OH)2D3 or other metabolites was minimal in these rats, 24,25-(OH)2D3 appears to act without being converted into other metabolites. These results demonstrate that 24,25-(OH)2D3 rapidly stimulates the metabolism of 1,25-(OH)2D3 and reduces its serum level. It is suggested that 24,25-(OH)2D3 plays a role in modifying serum 1,25-(OH)2D3 concentrations by affecting the metabolism of 1,25-(OH)2D3 and may have a therapeutic values in the treatment of hypercalcemia or hypercalciuria caused by 1,25-(OH)2D3 excess.     

Serum vitamin D level and bone mineral density in premenopausal Egyptian women with fibromyalgia

Patients with fibromyalgia syndrome (FMS) have impaired mobility and therefore get less sunlight exposure, we postulated that they may be at increased risk of developing osteoporosis (OP). The aim of this study was to assess and compare serum vitamin D level and bone mineral density (BMD) value in patients with primary FMS (PFMS) and healthy controls. A total of 50 patients with PFMS participated in this case–control study, and 50 healthy females who were age-matched to the patients were used as the control group. Venous blood samples collected from all subjects were used to evaluate serum 25-hydroxyvitamin D3 (25-OHD). BMD was measured at the lumbar spine (L2–L4) anteroposterior, femoral neck and forearm by dual-energy X-ray absorptiometry. Patients with PFMS had significantly lower serum 25-OHD than controls (15.1 ± 6.1 and 18.8 ± 5.4 ng/ml, respectively, p = 0.0018). Apart from the BMD in the lumbar spine, which was significantly lower in the PFMS patients compared with controls (p = 0.0012), no significant difference was found in other measures of BMD. Compared to PFMS patients who had serum level of the 25-OHD >20 ng/ml, the patients with 25-OHD ≤20 ng/ml are more likely to have impaired short memory (46.4 vs. 13.6%, respectively, p = 0.0136), confusion (50 vs. 18.2%, respectively, p = 0.0199), mood disturbance (60.7 vs. 27.3%, respectively, p = 0.0185), sleep disturbance (53.6 vs. 22.7%, respectively, p = 0.0271), restless leg syndrome (57.1 vs. 27.3%, respectively, p = 0.0346) and palpitation (67.9 vs. 36.4%, respectively, p = 0.0265). Serum level of the 25-OHD is inversely correlated with visual analogue scale (VAS) of pain (p = 0.016), Beck score for depression (p = 0.020) and BMD at lumbar spine (p = 0.012). The lumbar BMD inversely correlated with VAS of pain (p = 0.013) and Beck score for depression (p = 0.016). This study confirmed high prevalence of hypovitaminosis D among in patients with PFMS. This study confirmed the concept that FMS is a risk factor for OP. Based on this, an early nutrition program rich in calcium and vitamin D, appropriate exercise protocols, and medical treatment should be considered in these patients in terms of preventing OP development.     

Differentiation of normal human bone cells by transforming growth factor-beta and 1,25(OH)2 vitamin D3.

To investigate the role of transforming growth factor-beta 1 (TGF beta) in bone metabolism, the effects of this agent on the differentiation characteristics of human bone cells were studied in vitro. Human bone cells were isolated from femoral head samples by collagenase digestion. Differentiation characteristics included alkaline phosphatase activity, osteocalcin production, and mRNA levels for alkaline phosphatase, type I alpha 2-procollagen, and osteocalcin. The effect of TGF beta on alkaline phosphatase was not constant, but varied with the incubation conditions. At high cell density and in the presence of serum, TGF beta decreased alkaline phosphatase activity. However, at low cell density and under serum-free conditions, TGF beta stimulated alkaline phosphatase activity. The addition of 1,25(OH)2 vitamin D3 also stimulated alkaline phosphatase. The combination of the two agents gave a greater increase in activity than the sum of the activities when the two agents were given alone. The percentage of cells that stain positively for alkaline phosphatase changed in parallel with the change in specific activity. The percentage of positive cells increased from 17% to 64%, while the specific activity increased from 22 to 169 mU/mg protein. To investigate the mechanism of this stimulation, mRNA levels were measured at 24 hours. Individually, TGF beta and 1,25(OH)2D3 increased message levels for alkaline phosphatase and type I procollagen, but the greatest effect was produced by the combination of the two factors. 1,25(OH)2D3 increased osteocalcin mRNA levels, but TGF beta markedly inhibited this stimulation. TGF beta also inhibited production of osteocalcin by the human bone cells. TGF beta appears to modulate differentiation of human bone cells in combination with 1,25(OH)2D3 and other factors.     

Calcium and vitamin D supplementation and loss of bone mineral density in women undergoing breast cancer therapy

An unintended consequence of breast cancer therapies is an increased risk of osteoporosis due to accelerated bone loss. We conducted a systematic review of calcium and/or vitamin D (Ca ± D) supplementation trials for maintaining bone mineral density (BMD) in women with breast cancer using the “before–after” data from the Ca ± D supplemented comparison group of trials evaluating the effect of drugs such as bisphosphonates on BMD. Whether Ca ± D supplements increase BMD in women undergoing breast cancer therapy has never been tested against an unsupplemented control group. However, results from 16 trials indicate that the Ca ± D doses tested (500–1500 mg calcium; 200–1000 IU vitamin D) were inadequate to prevent BMD loss in these women. Cardiovascular disease is the main cause of mortality in women with breast cancer. Because calcium supplements may increase cardiovascular disease risk, future trials should evaluate the safety and efficacy of Ca ± D supplementation in women undergoing breast cancer therapy.     

Simvastatin increases bone mineral density in hypercholesterolemic postmenopausal women

Statins are able to reduce cardiovascular morbility and mortality mainly through their hypocholesterolemic effect. Beyond the inhibition of cholesterol synthesis, the identification of "ancillary" mechanisms has motivated studies evaluating the relationship between the use of statins and the modification of bone mineral density (BMD). To date, clinical trials have provided discordant results. The aim of our study was to evaluate whether simvastatin treatment (40 mg/d) could modify BMD in hypercholesterolemic women (n = 40) after a 2-year treatment as compared with a control group treated only with diet (n = 20) and matched by gender, age, body mass index (BMI), lipids, menopausal age, and BMD and the number of osteopenic, osteoporotic, and normal women (on the basis of T-score value). Exclusion criteria were secondary hyperlipemias and osteoporosis and current or previous therapy with statins, bisphosphonates, and estrogens. The BMD was measured at the lumbar spine and hip by dual energy x-ray absorpiometry (DEXA). In the group treated by simvastatin, BMD, both on the spine and femoral hip, showed a significant increase after 8 and 24 months, respectively (0.878 +/- 0.133 v 0.893 +/- 0.130 and 0.907 +/- 0.132; 0.840 +/- 0.101 v 0.854 +/- 0.101; and 0.863 +/- 0.10, P <.001); there was a percentage increase of 1.7% after 8 months and 3.3% after 24 months at the spine; at the femoral hip, BMD increased 1.6% after 8 months and 2.7% after 24 months. The group treated only with hypolipidic diet demonstrated after 8 and 24 months a slight decrease in BMD both on the spine and femoral hip (respectively, 0.884 +/- 0.175 v 0.872 +/- 0.174 and 0.861 +/- 0.164; 0.860 +/- 0.110 v 0.853 +/- 0.096 and 0.847 +/- 0.095; P <.05). In conclusion, as partly suggested by retrospective or observational data, this longitudinal study indicates that simvastatin treatment exerts a beneficial effect on BMD.     

Effect of age on plasma 1,25-(OH)2 vitamin D in the rat

Levels of plasma calcium, phosphorus, creatinine and 1,25-(OH)₂-D were measured in healthy male Sprague-Dawley rats aged 6 months (mature) and 20–24 months (senescent). Plasma 1,25-(OH)₂-D levels fell from 95 ± 50 pmol/l in the mature rats to 41 ± 10 pmol/l in the senescent rats (p < 0.01). Despite a significant fall in plasma phosphate from 3.06 ± 0.37 mmol/l to 2.54 mmol/l (p < 0.005) in the two groups, respectively, plasma calcium remained constant at about 2.4 mmol/l in both groups.     

Contrasting effects of exogenous 1,25-dihydroxyvitamin D [1,25-(OH)2D] versus endogenous 1,25-(OH)2D, induced by dietary calcium restriction, on vitamin D receptors

The biological actions of 1,25-dihydroxyvitamin D [1,25-(OH)2D] are mediated by specific binding of the hormone with an intracellular vitamin D receptor, which ultimately regulates expression of genes within the target tissues. The quantity of vitamin D receptors varies between target tissues and within target tissues, depending on the physiological state of the animal. One factor that can modulate tissue vitamin D receptor content is 1,25-(OH)2D. In the present study performed in male rats, exogenous administration of 36 ng 1,25-(OH)2D3/day for 7 days increased plasma 1,25-(OH)2D concentrations 5-fold above those in control rats (to 261 +/- 17 pg/ml). Compared with those in control rats, 1,25-(OH)2D3 treatment resulted in a 1.5-fold increase in duodenal vitamin D receptor content (351 +/- 16 vs. 520 +/- 21 fmol/mg protein) and a 3-fold increase in renal vitamin D receptor content (60.3 +/- 5.2 vs. 193.8 +/- 22.7 fmol/mg protein). The effects of endogenously produced 1,25-(OH)2D on tissue vitamin D receptor content were studied by feeding rats either a 0.02% or 1% calcium diet for 2, 7, 14, or 21 days. Rats fed the low calcium diet exhibited plasma 1,25-(OH)2D concentrations similar to (day 7) or exceeding (days 14 and 21) those achieved by exogenous administration of 1,25-(OH)2D3, yet duodenal vitamin D receptor content was not up-regulated by dietary calcium restriction at any time point. The renal vitamin D receptor content of calcium restricted rats was 20-38% lower (P less than 0.05) than that in rats fed a calcium-replete diet 7, 14, and 21 days after initiation of the dietary treatments. These data suggest that under physiological conditions, increased plasma concentrations of 1,25-(OH)2D do not result in up-regulation of tissue vitamin D receptor concentrations, and that dietary calcium restriction must induce some factor(s) that results in down-regulation of vitamin D receptors in the kidney.     

1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] increases insulin-like growth factor I (IGF-I) receptors in clonal osteoblastic cells. Study on interaction of IGF-I and 1,25-(OH)2D3

We previously reported a cooperative effect between insulin-like growth factor I (IGF-I) and 1,25-dihydroxy-vitamin D3 [1,25-(OH)2D3] in murine clonal osteoblastic cells, MCT3T3-E1. In the present study, the possible mechanism of interaction between these hormones was investigated. The effect of IGF-I on 1,25-(OH)2D3 receptors in MC3T3-E1 cells was examined. The affinity and hormone binding capacity of 1,25-(OH)2D3 receptors were not altered by IGF-I. Immunoblot analysis showed about 54 kilodaltons (kDa) 1,25-(OH)2D3 receptors, similar to that observed for mouse fibroblasts. The synthesis of IGF-I by the cells under a serum-free condition was determined by RIA. The assay revealed immunoreactive IGF-I secreted by MC3T3-E1 cells (1.79 +/- 0.04 x 10(-9) M, mean +/- SE, n = 5). Rat GH significantly increased the concentration of IGF-I, but 1,25-(OH)2D3 did not. IGF-I radioligand-receptor assay revealed specific binding of IGF-I to MC3T3-E1 cells. The relative potency of IGF-I-related peptides to bind with the cells was in the order of IGF-I much greater than multiplication-stimulating activity (the rat homologue of IGF-II) greater than insulin, and the receptor protein migrated as a 130-kDa band in autoradiography. Scatchard analysis showed a significant increase in IGF-I binding sites by 50% after 3-day treatment with 5 x 10(-11) M 1,25-(OH)2D3, without any change in affinity. These results indicate that the interaction of IGF-I and 1,25-(OH)2D3 in the culture of MC3T3-E1 cells may be mediated by the effect of 1,25-(OH)2D3 on IGF-I receptors.     

Effects of vitamin D3, 25(OH) vitamin D3, 24,25(OH)2 vitamin D3, and 1,25(OH)2 vitamin D3 on the in vitro intestinal calcium absorption in the marine teleost, Atlantic cod (Gadus morhua)

The role of vitamin D3, 25(OH) vitamin D3, 24,25(OH)2 vitamin D3, and 1,25(OH)2 vitamin D3, in the regulation of calcium absorption across the intestine in the marine teleost, Gadus morhua, was investigated. The intestine was perfused, in vitro, both vascularly and through the intestinal lumen, and the calcium influx was measured using 45Ca. Vitamin D3 and its metabolites were tested in perfusate concentrations of 10 ng.ml-1.25(OH)D3 increased the intestinal calcium uptake by 65%, while 24,25(OH)2D3 decreased it by 36%. Vitamin D3 and 1,25(OH)2D3, on the other hand, did not affect the calcium influx across the intestinal mucosa. This indicates that 25(OH)D3 and 24,25(OH)2D3 may be active regulators of calcium transport across the intestine of Atlantic cod.     

The importance of vitamin C for hydroxylation of vitamin D3 to 1,25(OH)2D3 in man

Summary The effects of vitamin C on 1,25(OH)2D3 synthesis in humans were evaluated; the study included 20 females. They were divided into 2 groups. The first of the 10 subjects (age range 55–71) received ascorbic acid at a dose of 150 mg/die i.v. for 10 days; the second 10 subjects (age range 55–69) received a placebo i.v. for 10 days. In a later study (after a 30-day washout) the same two groups were tested for the second time with ascorbic acid at a dose of 1,000 mg/die i.v. for 10 days and placebo i.v. for 10 days. Serum calcium and phosphorus, serum Ca++, serum proteins, blood and urinary pH, serum 25(OH)D3 and 1,25(OH)2D3, serum PTH, urinary hydroxyprolin were tested before and after the treatments. In the first study a significant increase in serum 1,25(OH)2D3 was observed after ascorbic acid while no significant variation was observed for the other parameters. In the second study, a significant increase in serum Ca++ and a significant decrease in serum 1,25(OH)2D3 were observed after ascorbic acid while no significant variation was observed for the other parameters. The authors conclude that ascorbic acid promotes 1,25(OH)2D3 synthesis at a paraphysiologic dose (150 mg/die) in humans but this synthesis is inhibited at higher doses (1,000 mg/die). The latter effect by Ca++ or by an effect of ascorbate on 1 alpha-hydroxylase enzyme could be mediated.     

Adjuvant oestrogen treatment increases bone mineral density in postmenopausal women with rheumatoid arthritis.

OBJECTIVES--The beneficial effect of oestrogens on bone mineral density in women with osteoporosis is well known. Patients with rheumatoid arthritis (RA) are at risk for osteoporosis. A study was therefore set up to investigate the effects of adjuvant oestrogen treatment on bone metabolism and bone mineral density in postmenopausal women with RA. METHODS--Forty postmenopausal women with active RA were admitted to a placebo controlled, double blind study investigating the beneficial effect of adjuvant oestradiols or placebo on bone metabolism and bone mineral density. Thirty three patients completed 52 weeks of treatment. RESULTS--At the start both treatment groups were comparable for all parameters. In the oestrogen group serum concentrations of osteocalcin decreased and concentrations of sex hormone binding globulin increased during the study. Bone mineral density measured by dual energy x ray absorptiometry increased significantly in the lumbar vertebral spine and femoral neck in the oestrogen group compared with the placebo group. CONCLUSIONS--This study shows that the use of adjuvant oestrogens in post-menopausal women with active RA increases bone mineral density.     

Bone mineral density increases with vitamin D repletion in patients with coexistent vitamin D insufficiency and primary hyperparathyroidism

Two hundred and twenty-nine consecutive subjects, 202 women and 27 men, referred for evaluation of osteoporosis or low bone mineral density (BMD) had serum measurements of immunoreactive PTH (iPTH) and 25-hydroxyvitamin D (25OHD) performed. Fifteen individuals (mean age +/- SE, 75+/-2.4 yr) had depressed serum 25OHD (<15 pg/mL) and concomitantly elevated (>65 pg/mL) iPTH levels. After successful treatment of vitamin D insufficiency in all subjects, iPTH remained inappropriately high or frankly elevated in 5, describing a 2.2% prevalence rate of coexistent primary hyperparathyroidism and vitamin D insufficiency in our population. Despite persistent primary hyperparathyroidism, normalization of serum 25OHD levels in these 5 subjects increased their BMD at an annual rate of 6.3% and 8.2% in spine and hip, respectively. Our results suggest that coexistent vitamin D insufficiency can obscure the diagnosis of primary hyperparathyroidism and, when treated effectively, can result in substantial short-terms gains in BMD despite persistence of the inappropriate production of PTH.