Effects of Postmenopausal Hormone Replacement Therapy With and Without Vitamin D3 on Circulating Levels of 25-Hydroxyvitamin D and 1,25-Dihydroxyvitamin D

The effects of postmenopausal hormone replacement therapy (HRT) and vitamin D₃ on vitamin D metabolites (25OHD and 1,25(OH)₂D) were studied in a population-based prospective 1-year study. The serum concentrations of intact parathyroid hormone (PTH), calcium, and phosphate were also studied. A total of 72 women were randomized into four treatment groups: HRT group (sequential combination of 2 mg estradiol valerate and 1 mg cyproterone acetate), Vit D₃ group (vitamin D₃ 300 IU/day + calcium lactate 500 mg/day), HRT + Vit D₃ group (both above) and placebo group (calcium lactate 500 mg/day). Serum samples were taken in March–April, when vitamin D formation from sunlight in Finland is minimal after the dark winter. Serum concentrations of 25OHD increased in the Vit D₃ group (33.5%, P < 0.001) and in the HRT + Vit D₃ group (38.2%, P < 0.001) but had not changed significantly in the HRT and placebo groups at the 1-year follow-up examination. Serum concentrations of calcitriol (1,25(OH)₂D) increased, however, only in the HRT group (23.7%, P < 0.05), and remained unchanged in other groups. Serum concentrations of PTH decreased by 23.2% (P < 0.05) in the placebo group, but did not change significantly in the other three groups. The concentrations of serum calcium increased in the nonhormone groups (P < 0.001), whereas serum phosphate concentrations decreased in the hormone groups (P < 0.05 and 0.001). Our results confirm the positive effect of 1 year of HRT on serum calcitriol. Vitamin D₃ supplementation increased 25OHD concentrations, but did not affect calcitriol concentrations even though the initial levels were low. Interestingly, the combination of HRT and vitamin D₃ did not increase serum calcitriol concentrations as much as HRT alone. Received: 14 June 1996 / Accepted: 17 June 1997     

Decrease in bone level of 1,25-dihydroxyvitamin D in women over 45 years old

Summary The most active metabolite of vitamin D is 1,25-dihydroxyvitamin D [1,25(OH)₂D]. Its level in the bone may play a role in the pathogenesis of metabolic bone diseases such as osteoporosis. To assess this, and to see whether there is correlation between serum and bone levels, we studed serum and bone samples taken from 43 patients (18 men and 25 women) undergoing different orthopedic procedures. Patients were studied according to sex and age groups (<45 years, 46–60 years, >61 years). Serum level of 1,25(OH)₂D was found to be 29.7±2.61 pg/ml (mean±SEM) for women, 32.2±3.86 pg/ml for men, and 30.7±2.18 pg/ml for the group as a whole. No significant statistical differences were found among age subgroups in either sex or between sexes. Bone level of 1,25(OH)₂D was found to be 31.5±4.46 pg/g for women, 26.5±3.06 pg/g for men, and 29.4±2.81 pg/g for the entire group. No significant statistical difference was found between the age subgroups for men. However, the level of 1,25(OH)₂D was found to be higher in the group of younger women (<45 years) compared with the older women (46–60 years and >61 years) (P<0.005).Prof. T. Reichstein Professor of Biochemistry     

Influence of estrogen-progestin replacement therapy and exercise on lumbar spine mobility and low back symptoms in a healthy early postmenopausal female population: a 2-year randomized controlled trial

The purpose of this study was to examine the influence of estrogen-progestin replacement therapy and exercise on the lumbar spine mobility and back symptoms of early postmenopausal women. The population sample consisted of 78 healthy, 49- to 55-year-old women, 0.5–5 years after menopause, who were randomized into three groups, two receiving different protocols of estradiol valerate combined with medroxyprogesterone acetate replacement therapy, and the third group a placebo. These groups were then randomized into exercise and control cases and monitored for 2 years. The mobility of the lumbar spine was measured and symptoms investigated using the Million and Oswestry pain and disability questionnaires and pain drawings at the baseline and after 1 and 2 years. During the follow-up, the mobility of the lumbar spine decreased in all six groups. The decrease was most evident in those who had been the most flexible at baseline (P < 0.0001). The decrease was less notable in the hormone replacement therapy groups than in the control group. When the replacement therapy groups were pooled together, the difference was significant at a P < 0.05 level. No difference was seen between the hormone combinations. The exercise intervention was insufficient to influence lumbar spine mobility. Only sporadic cases of back symptoms appeared and disappeared among the subjects during the follow-up, and no preventive or aggravating effects of hormone replacement therapy or the exercise program on symptoms were detected. Received: 27 August 1997 Revised: 21 January 1998 Accepted: 18 June 1998     

Influence of age on effects of endogenous 1,25-dihydroxyvitamin D on calcium absorption in normal women

Recent reports of increases in serum 1,25-dihydroxyvitamin D [1,25(OH₂)D] concentration with aging despite no changes or decreases in calcium absorption suggest that elderly women have intestinal resistance to vitamin D action. Thus, in 15 young adult (30±1 year) and 15 elderly (74±1 year) women (mean±SE), we assessed the responsiveness of intestinal calcium absorption to increases in circulating 1,25(OH)₂D induced by 4 days of an experimental diet (150 mg calcium and 1600 mg phosphorus daily). True fractional calcium absorption (FCA) (⁴⁴Ca mixed with food and ⁴²Ca given intravenously, then their ratio in urine measured by mass spectrometry) was determined. Baseline serum intact parathyroid hormone (PTH) concentration was higher in the older women (P=0.01) whereas serum 1,25(OH)₂D concentration and true FCA were similar. In both groups, serum 1,25(OH)₂D concentrations increased (P<0.002) on the experimental diet. After 4 days on the diet, serum 1,25(OH)₂D increased over baseline by 30.5 and 35.6% and, despite these increases, true FCA was 40±3 versus 40±4%/24 hours (NS between groups) in the young and elderly women, respectively. These data suggest that either elderly women have normal intestinal responsiveness to vitamin D or that the resistance to it is too mild to be detected by these methods.     

Serum 1,25-dihydroxyvitamin D concentration in hypophosphatemic vitamin D-resistant rickets

Summary Fasting serum 1α,25-dihydroxyvitamin D (1,25-(OH)₂D) levels were measured in 3 groups of hypophosphatemic vitamin D-resistant rickets (VDRR) patients: those untreated; those treated with vitamin D and phosphate; and those treated with 1,25-(OH)₂D₃ and phosphate. In the untreated patients, the mean 1,25-(OH)₂D level was higher than in our age-matched control group. Except for one at 66 pg/ml, individual values were however within normal limits. Long term vitamin D₂ therapy was accompanied by a slight but significant decrease in 1,25-(OH)₂D concentrations; nonetheless the levels remained within the normal range. In the third group of patients, the concentration of 1,25-(OH)₂D rose to supranormal levels when sampling was done 1–3 hours after administration of the hormone, decreasing rapidly to levels below that of normal subjects when the specimens were collected 12–24 hours later. Our data show that an alteration of the vitamin D activation pathway is unlikely to be part of the pathogenic mechanism underlying the VDRR condition. Calcitriol (1α,25-(OH)₂D₃) as Rocaltrol^R in capsules of 0.25 and 0.50 μg was kindly supplied by Dr. Patrick Le Morvan (Hoffmann-La Roche Ltd, Vaudreuil, Que., Canada).     

Effect of 1,25-dihydroxyvitamin D3 on osteopenia induced by prednisolone in adult rats

Summary Adult male rats were fed a diet containing 0.15% calcium, 0.3% phosphorus, and either 100, 50, or 20 mg of prednisolone per kg of diet. All these levels of prednisolone led to osteopenia, decreased intestinal absorption of calcium, slightly lower serum calcium and phosphorus, and a decreased level of serum 1,25-dihydroxyvitamin D₃. Exogenous parenteral 1,25-dihydroxyvitamin D₃ corrected steroid-induced changes in serum calcium and phosphorus, but could not completely correct the low intestinal calcium transport; nor did it prevent the development of osteopenia. The prednisolone-induced osteopenia seems at least in part to be caused by impaired intestinal calcium transport. The impaired calcium transport may be the result of low levels of 1,25-dihydroxyvitamin D₃ and a direct effect of presnisolone on the intestine. No reprints of this article will be available from the authors.     

Decrease in bone levels of 1,25-dihydroxyvitamin D in women with subcapital fracture of the femur

Summary In a previous study we were able to show that in women over the age of 45 the level of 1,25-dihydroxyvitamin D (1,25(OH)₂D) in bone, but not in serum, is significantly reduced when compared with younger women. In the present study we measured the concentration of 1,25(OH)₂D in sera and bones of 19 female patients with subcapital fractures of the femur, mean age 78±2 years. We were able to show that serum levels of 1,25(OH)₂D were within the normal range, while bone levels were markedly reduced compared to levels in femoral bone obtained from young female cadavers or to the previously reported levels in non-osteoporotic elderly women. Thus, reduced levels of 1,25(OH)₂D in bones of elderly women may lead, together with other factors, to subcapital fractures.Holder of Prof. T. Reichstein Professorial Chair     

骨化三醇预防大鼠原位肝移植后急性排斥的动态观察

目的探讨骨化三醇在预防大鼠原位肝移植后急性排斥反应中的作用。方法大鼠原位肝移植分为Wistar→Wistar同基因组 (Ⅰ组 ) ,SD→Wistar急性排斥组 (Ⅱ组 )和SD→Wistar环孢菌素治疗组 (Ⅲ组 ) ,SD→Wistar骨化三醇治疗组 (Ⅳ组 ) ,在移植后 1,5 ,7,15 ,30d各个时点检测肝脏功能、急性排斥反应、细胞因子表达等指标。结果Ⅳ组大鼠移植后 4 /6生存期大于 10 0d ,与Ⅱ组比较差异有显著意义 (P <0 0 0 1)。Ⅳ组大鼠移植后各时点平均AST(12 7± 4 1)U/L～ (36 0± 10 4 )U/L ,平均BIL(13± 5 )mmol/L～ (38± 11)mmol/L(与Ⅱ组比较 ,P <0 0 5 )。Ⅳ组移植后各时点平均排斥反应活动度积分 0分～ (3 3± 1 6 )分 (与Ⅱ组比较 ,P <0 0 5 )。Ⅳ组大鼠移植后各时点肝组织内IFN γmRNA表达明显减弱 ,IL 10mRNA表达明显增强 (与Ⅱ组比较 ,P <0 0 5 )。结论原位肝移植后骨化三醇治疗可以诱导细胞因子分泌向TH2型偏移 ,有效抑制急性排斥反应。     

Modulation of vitamin D increased H2O2 production and MAC-2 expression in the bone marrow-derived macrophages by estrogen

The calcium-regulating hormone 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) is recognized as an immunomodulator. Members of the macrophage-monocyte lineage are targets for 1,25(OH)₂D₃ action. The hormone enhances the ability of bone marrow-derived macrophages (BMDMs) to produce H₂O₂, increases the expression of the macrophage specific surface antigen MAC-2, increases the release of tumor necrosis factor- (TNF-), and inhibits BMDM proliferation. In the present study we examine the possibility that estrogen modulates 1,25(OH)₂D₃ effects on BMDMs. The active form, 17-estradiol, failed to affect any of the BMDM functions by itself. On the other hand, 17-estradiol increased the effects of 1,25(OH)₂D₃ production by BMDMs and on MAC-2 expression on these cells. The inactive estrogen analog 17-estradiol was unable to elicit these effects. Moreover, 17-estradiol did not affect the lipopolysaccharide (LPS)-induced increase in H₂O₂ production by BMDMs. Modulation of BMDM proliferation and TNF- release from these cells by 1,25(OH)₂D₃ were not affected by the estrogen. The experiments were performed with BMDMs harvested from vitamin D-depleted and repleted mice, and always under similar conditions, the various functions were more pronounced in the cells derived from the repleted mice. Our data are consistent with the hypothesis that 17-estradiol modulates the interactions of 1,25(OH)₂D₃ with BMDMs and consequently is able to affect biological responses to 1,25(OH)₂D₃ in these cells. We propose that this cell system is a convenient, nontransformed model for studying cellular activities of 1,25(OH)₂D₃.     

Vitamin D and HRT: No benefit additional to that of HRT alone in prevention of bone loss in early postmenopausal women. A 2.5-year randomized placebo-controlled study

The study was designed to examine the effect of hormone replacement therapy (HRT) and low-dose vitamin D (Vit D) supplementation on the prevention of bone loss in non-osteoporotic early postmenopausal women and to determine whether Vit D supplementation can give additional benefit to an already optimized estrogen regimen. The effects of HRT and Vit D on bone mineral density (BMD) were studied in postmenopausal women in a 2.5-year randomized placebo-controlled study. The study population was a subgroup of the Kuopio Osteoporosis Risk Factor and Prevention Study (OSTPRE) (n=13100). A total of 464 early postmenopausal women were randomized to four groups: (1) HRT (a sequential combination of 2 mg estradiol valerate and 1 mg cyproterone acetate (E₂Val/CPA); (2) vitamin D₃ (cholecalciferol, 300 IU/day); (3) HRT+Vit D; and (4) placebo (calcium lactate; 93 mg Ca²⁺/day). Lumbar (L1–4) and femoral neck BMD were determined by dual-energy X-ray absorptiometry before and after 2.5 years of treatment. After 2.5 years, lumbar BMD had increased by 1.8% in the HRT group (p<0.001) and by 1.4% in the HRT+Vit D group (p=0.002), whereas lumbar BMD had decreased by 3.5% (p<0.001) in the Vit D group and by 3.7% (p<0.001) in the placebo group. The loss of femoral neck BMD was lower in the HRT (–0.3%) and the HRT+Vit D (–0.9%) groups compared with the Vit D (–2.4%) and the placebo groups (–3.7%). This study confirms the beneficial effect of HRT on BMD. It also shows that low-dose vitamin D supplementation has only a minor effect in the prevention of osteoporosis in non-osteoporotic early postmenopausal women and does not give any benefit additional to that of HRT alone.     

Autosomal dominant hypophosphataemia with elevated serum 1,25 dihydroxyvitamin D and hypercalciuria

A 14-year-old boy presented with the clinical and radiological features of rickets. Serum inorganic phosphate levels were constantly low, whereas serum calcium and parathyroid hormone levels were within the normal range. Laboratory investigation did not show any evidence for vitamin-D deficiency, chronic renal insufficiency, Fanconi syndrome, tubular acidosis, hepatic disease or intestinal malabsorption. A family study comprising 34 members over four generations revealed 10 other individuals to be affected and the mode of inheritance to be autosomal dominant. In addition to hypophosphataemia and normocalcaemia, the diasease is characterized by elevated serum 1,25 dihydroxyvitamin D levels and hypercalciuria. This hereditary syndrome of renal hypophosphataemia differs from the common familial X-linked hypophosphataemia and the recently described autosomal recessive hypophosphataemic rickets with hypercalciuria by its dominant mode of inheritance; it differs from hypophosphataemic non-rachitic bone disease by the elevated serum 1,25 dihydroxyvitamin D levels and hypercalciuria.     

Serum 1,25-dihydroxyvitamin D concentrations in premature infants: Preliminary results

Summary Serum 1,25(OH)₂D concentrations were measured in serial serum samples from 19 premature infants of 29.6±1.3 weeks gestation and 1,129±159 g birthweight. 1,25(OH)₂D was always normal or elevated and mean concentrations increased with age (adult, 55.2±13; infants, 1–2 weeks, 81.5±37.7 pg/mg; 3 weeks, 65±21; 6 weeks, 90.0±17.3; 9 weeks, 99.0±25.1; 12 weeks, 103.3±26.6 pg/ml). No correlation was seen with 25-OHD. Infants given 800 IU D₂ supplements had lower 1,25(OH)₂D levels than infants given 400 IU D₂. Breast fed infants had initially higher 1,25(OH)₂D levels; however, this was not sustained. These preliminary data suggest that premature infants regulate 1,25(OH)₂D production similar to more mature infants and children. Whether the premature infant has a normal gastrointestinal and/or bone responsiveness to 1,25(OH)₂D and whether these elevated 1,25(OH)₂D concentrations are “adequately elevated” requires further study. NIH Grant 2R01HD-09998-06.     

Higher 1,25-dihydroxyvitamin D3 concentrations associated with lower fall rates in older community-dwelling women

Introduction The purpose of this study was to examine the relationships of vitamin D supplementation and serum concentrations of vitamin D metabolites and parathyroid hormone (PTH) with neuromuscular function and falls in older community-dwelling women.Methods We examined these relationships using a 4-year prospective multi-center study among 9,526 community-dwelling women enrolled in the Study of Osteoporotic Fractures (median age: 70 years; interquartile range: 67–75) and a subset of 389 women (97%) out of 400 who were randomly selected from the entire cohort for serum measures. Measurements included: vitamin D supplementation, serum 25-hydroxyvitamin D₃ [25(OH)D₃], serum 1,25-dihydroxyvitamin D₃ [1,25(OH) ₂D₃], and serum intact parathyroid hormone (iPTH); grip and quadriceps strength, chair-stand time, walking speed, reaction time, and balance-walk time (including changes in grip strength, chair-stand time, walking speed and balance-walk time over approximately 3.7 years); and incident fall rates (number of falls/woman-years).Results In 9,526 women, vitamin D supplementation was not associated with any measures of neuromuscular function, change in neuromuscular function, or fall rates (p>0.01 for all). In a subgroup of 389 women, there was a trend of higher 25(OH)D₃ concentration with slightly weaker grip strength (p=0.007), and women in the fourth quartile of 1,25(OH)₂D₃ had a faster chair-stand time (p=0.017) than women in the first quartile; still, in general, concentrations of 25(OH)D₃, 1,25(OH)₂D₃, and iPTH were not associated with either neuromuscular function or changes in neuromuscular function (p>0.05 for all). However, higher 1,25(OH)₂D₃ concentration was associated with lower fall rates (p=0.039).Conclusions Higher 1,25(OH)₂D₃ concentration is associated with a lower fall risk in older community-dwelling women, but vitamin D supplementation, and 25(OH)D₃ and iPTH concentrations are not associated with either neuromuscular function or falls.     

Relationship between serum 1,25-dihydroxyvitamin D and mortality in patients with pre-dialysis chronic kidney disease

Background It is known that vitamin D has many functions besides involvement in calcium metabolism. It has recently been recognized that vitamin D deficiency is associated with mortality, especially in cardiovascular disease (CVD). Vitamin D deficiency is common in end-stage renal disease, but develops from the early stage of chronic kidney disease (CKD). So we investigated whether the serum level of the activated form of vitamin D (1,25-dihydroxyvitamin D) affected mortality in patients with CKD stages 3 and 4. Methods Between January 1, 1995, and June 30, 2006 we measured serum 1,25-dihydroxyvitamin D In 226 patients with CKD stages 3 and 4 and classified the results into two groups depending on whether the level was below (group I) or above (group II) 20 pg/ml. We ended the follow-up period on December 31, 2006. We compared all-cause and cardiovascular mortality between the two groups. We also examined predictors of mortality by using Cox proportional regression analysis. Results Two-hundred and twenty-six patients (67 men and 159 women, mean age 67.0) were registered in this study, and groups 1 and 2 comprised 84 and 142 patients, respectively. During the follow-up period 43 patients died. CVD was the major cause of death, followed by infectious disease. The Kaplan–Meier survival curve revealed that all-cause mortality was significantly higher in group I, but a significant difference between CVD mortality in the two groups was not demonstrated. By Cox proportional regression analysis, group I was related to all-cause mortality, but this was not proved to be an independent predictor. Conclusion The results suggested that serum level of 1,25-dihydroxyvitamin D was associated with all-cause mortality in patients with CKD stages 3 and 4.     

Lack of In vitro evidence for storage of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) and 1,25(OH)2D3 binding protein in skeletal matrix

A few studies have reported on the measurement of 1,25-dihydroxycholecalciferol (1,25(OH)₂D₃) in bone, using chloroform/methanol extraction and radioreceptor assay. As the significance of bone 1,25(OH)₂D₃ content was not defined in any of these reports, the objective of the current investigation was to determine whether 1,25(OH)₂D₃ may be stored in skeletal matrix. Bone powder samples from the iliac crest were extracted in ethylacetate/cyclohexane and 1,25(OH)₂D₃ isolated from the extract by means of Sephadex LH-20 and high pressure liquid chromatographic separation and subsequently measured by radioimmunoassay (RIA). Within the detection range of the RIA, no 1,25(OH)₂D₃ could be measured, suggesting that 1,25(OH)₂D₃ is not stored in skeletal matrix. Vitamin D bone concentrations previously measured may therefore have reflected plasma contamination. Consistent with this hypothesis, only traces of skeletal 1,25(OH)₂D₃ binding protein were measured when compared with serum values. Although 1,25(OH)₂D₃ may act as a potential local determinant of bone remodeling, there is no evidence supporting a delayed paracrine function by matrix-derived 1,25(OH)₂D₃.     

小剂量环孢素A和骨化三醇联用预防大鼠原位肝移植后急性排斥反应的效果

目的　探讨小剂量环孢素A(CsA)和骨化三醇 [1,2 5 (OH) 2 D3 ]对预防原位肝移植后急性排斥反应的协同效应。方法　以SD大鼠和Wistar大鼠分别作为供者和受者 ,采用Kamada方法建立大鼠原位肝移植模型。受者随机分成Ⅰ、Ⅱ、Ⅲ、Ⅳ组。Ⅰ组为对照组 ;Ⅱ组和Ⅲ组移植后分别接受全剂量CsA和全剂量骨化三醇治疗 ;Ⅳ组移植后接受小剂量CsA和骨化三醇联合治疗。观察移植后生存期及移植后 5、7、12d肝组织病理学变化和IFN γmRNA表达水平等指标。结果　Ⅳ组 5 / 6受者长期存活 ,生存期较Ⅰ组显著延长 (P <0 .0 5 ) ;与Ⅱ组或Ⅲ组比较 ,差异均无显著性 (P >0 .0 5 )。Ⅳ组移植后各时点排斥反应平均病理学分级分别为 0 .6 7,1和 0 .6 7级 ,较Ⅰ组减低 ,差异有显著性 (P <0 .0 5 ) ;与Ⅱ组或Ⅲ组比较 ,差异均无显著性 (P >0 .0 5 )。Ⅳ组肝组织IFN γmRNA表达处于低水平 ,较Ⅰ组明显受抑制 (P <0 .0 5 ) ;与Ⅱ组比较 ,差异无显著性 (P >0 .0 5 ) ;与Ⅲ组比较 ,除移植后 7d外 ,差异均无显著性 (P >0 .0 5 )。结论　原位肝移植后小剂量环孢素A和骨化三醇联用 ,可以有效预防急性排斥反应 ,延长受者生存期。两者具有明显的正协同作用。     

Serum vitamin D metabolites and nuclear uptake of (3H)-1,25-dihydroxyvitamin D3 in monocytes from patients with autosomal dominant osteopetrosis: a study of two radiological types

The nuclear uptake of (³H)-1,25 dihydroxyvitamin D₃ in freshly isolated human monocytes and the serum levels of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were investigated in 13 patients with autosomal dominant osteopetrosis and in sex- and age-matched controls. Seven patients had type I osteopetrosis characterized by diffuse, symmetrical osteosclerosis with pronounced sclerosis of the skull and increased thickness of the cranial vault. The other six patients had type II with “Rugger Jersey Spine” and “endobones” as characteristic findings. In type I osteopetrosis the serum 1,25-dihydroxy vitamin D was significantly reduced (p < 0.05), whereas serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D receptor binding were normal. In type II osteopetrosis the serum vitamin D metabolites were normal, as was the maximal binding capacity (Bmax) of 1,25-dihydroxyvitamin D to the nuclear receptor. The dissociation constant (Kd), however, was significantly increased (p < 0.01) indicating a modest resistance to 1,25-dihydroxyvitamin D. It is concluded that a general end-organ resistance to 1,25-dihydroxyvitamin D at the receptor level does not exist in type I osteopetrosis, but may contribute to some of the radiological and biochemical findings in type II.