[ association between vitamin D and bone mineral density in postmenopausal women]

There are inconsistent data regarding the role of vitamin-D in determining bone mineral density [BMD] especially in less severe vitamin-D deficiency. The aim of this study was to investigate the possible association between 25[OH]D and BMD in healthy free-living postmenopausal women in a population-based study. We enrolled 245 postmenopausal women, aged between 40 to 80 years, randomly selected from the Tehran Lipid and Glucose Study. Measurements of BMD were taken at the lumbar spine and upper femur by dual X-ray absorptiometry; additional to demographic and anthropometric data, serum 25[OH]D, PTH, calcium, phosphorus and alkaline phosphatase were measured according to the currently used laboratory methods. Bivariate and multivariate analyses were used to explore the association between 25[OH]D, BMD and other clinical and biochemical variables. Mean age and duration of menopause were 58 +/- 7 and 9.4 +/- 6.8 years, respectively; 25[OH]D [29.3 +/- 24.9 ng/ml] was <10 ng/ml and 11-20 ng/ml in 5.2% [n=13] and 37.6% [n=92] of women, respectively; 25[OH]D correlated inversely with LnPTH [r=-0.25, p<0.01]. However no association was found between 25[OH]D level and BMD at any of the skeletal scanning sites in bivariate analysis or multiple linear regression analyses, after adjusting for age, years since menopause, body mass index [BMI], calcium and LnPTH. In the multivariate analyses, BMD correlated inversely with LnPTH, in addition to age and BMI [R2=20%, p=0.03] only in femoral neck, but not at any other sites. This study showed no association between 25[OH]D and BMD in postmenopausal women

[Effect of different dosage of intramuscular vitamin D3 on serum 25[OH]D]

Pareneteral vitamin D3 administration, a common practice in Iran, is usually used based mainly on clinical symptoms or serum mineral disturbances. Since studies about the effects and side effects of parenteral vit D3 preparations are limited, this study was designed to evaluate the effect of different intramuscular vitamin D3 dosage on serum 25[OH]D levels. In this study, 54 health volunteers were selected, and randomly assigned to 4 groups, based on their serum vitamin D3. Mean body mass index, age and sex frequency were not significantly different between groups. Mean serum 25[OH]D levels before injections were 27.24 +/- 21.30, 25.21 +/- 17.09, 24.70 +/- 16.8 and 25.10 +/- 14.48 ng/mL in groups I to IV respectively. Vitamin D3 was injected in dosages of 300/000, 600/000, 900/000 units and placebo in groups I-IV respectively. 25[OH]D levels were determined before, and at 2 weeks, 2 months and 4 months after injection. Serum 25[OH]D levels before injection were significantly higher compared to levels assessed 2 and 4 months after injection. At the end of study, in groups I to III, mean serum 25[OH]D levels in group I to IV were 48.20 +/- 28.32 ng/mL, 65.46 +/- 33.52 ng/mL, 72.90 +/- 37.68 ng/mL, and 14.38 +/- 11.14 ng/mL respectively. Frequency of vitamin D hypervitaminosis in groups I, II and III was 9%, 38% and 40% respectively. Usage of parenteral vit D3, especially dosages higher than 300/000 III, is associated with a high risk of vitamin D hypervitaminosis

Hypoparathyroidism and pseudohypoparathyroidism / Hipoparatiroidismo e pseudohipoparatiroidismo

The principal function of the parathyroid hormone (PTH) is maintenance of calcium plasmatic levels, withdrawing the calcium from bone tissue, reabsorbing it from the glomerular filtrate, and indirectly increasing its intestinal absorption by stimulating active vitamin D (calcitriol) production. Additionally, the PTH prompts an increase in urinary excretion of phosphorus and bicarbonate, seeking a larger quantity of free calcium available in circulation. Two mechanisms may alter its function, limiting its control on calcium: insufficient PTH production by the parathyroids (hypoparathyroidism), or a resistance against its action in target tissues (pseudohypoparathyroidism). In both cases, there are significantly reduced levels of plasmatic calcium associated with hyperphosphatemia. Clinical cases are characterized by nervous hyperexcitability, with paresthesia, cramps, tetany, hyperreflexia, convulsions, and tetanic crisis. Abnormalities such as cataracts and basal ganglia calcification are also typical of these diseases. Treatment consists of oral calcium supplementation associated with increased doses of vitamin D derivatives.

A principal função do paratormônio (PTH) é a manutenção dos níveis plasmáticos de cálcio, retirando-o do tecido ósseo, reabsorvendo-o do filtrado glomerular e, indiretamente, aumentando sua absorção intestinal através do estímulo para a produção de vitamina D ativa (calcitriol). Além disso, o PTH promove um aumento na excreção urinária de fósforo e bicarbonato, objetivando uma maior quantidade de cálcio livre disponível na circulação. Dois mecanismos podem alterar sua função, limitando seu controle sobre o cálcio: produção insuficiente de PTH pelas paratiróides (hipoparatiroidismo), ou uma resistência à sua ação nos órgãos-alvo (pseudohipoparatiroidismo). Em ambos os casos, ocorre uma redução significativa dos níveis plasmáticos de cálcio em associação com hiperfosfatemia. Manifestações clínicas características são: hiperexcitabilidade nervosa, com parestesia, cãimbras, tetania, hiperreflexia, convulsões e crise tetânica. Catarata e calcificação dos gânglios basais são anormalidades típicas dessas doenças. O tratamento consiste da suplementação oral de cálcio, associada com doses elevadas de derivados da vitamina D.

Improvement of adynamic bone disease after renal transplantation

Low bone remodeling and relatively low serum parathyroid hormone (PTH) levels characterize adynamic bone disease (ABD). The impact of renal transplantation (RT) on the course of ABD is unknown. We studied prospectively 13 patients with biopsy-proven ABD after RT. Bone histomorphometry and bone mineral density (BMD) measurements were performed in the 1st and 12th months after RT. Serum PTH, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and osteocalcin were measured regularly throughout the study. Serum PTH levels were slightly elevated at transplantation, normalized at the end of the third month and remained stable thereafter. Bone biopsies performed in the first month after RT revealed low bone turnover in all patients, with positive bone aluminum staining in 5. In the 12th month, second biopsies were performed on 12 patients. Bone histomorphometric dynamic parameters improved in 9 and were completely normalized in 6, whereas no bone mineralization was detected in 3 of these 12 patients. At 12 months post-RT, no bone aluminum was detected in any patient. We also found a decrease in lumbar BMD and an increase in femoral BMD. Patients suffering from ABD, even those with a reduction in PTH levels, may present partial or complete recovery of bone turnover after successful renal transplantation. However, it is not possible to positively identify the mechanisms responsible for the improvement. Identifying these mechanisms should lead to a better understanding of the physiopathology of ABD and to the development of more effective treatments.

effect of dietary phosphorus restriction on the production of 1, 25[OH]2 D3 [calcitriol] in patients with moderate renal insufficiency

Renal osteodystrophy is common in chronic renal failure[CRF]. The retention of phosphate, the diminished production of calcitriol, the hypocalcaemia and the increased level of parathormone[PTH] are inter-related and basic pathogenetic factors 25 patients [14 male and 11 female] with average age of 51.7 +/- 10 years, all having moderate renal failure [glomerular filtration rate between 30-70 mI/minute] were included in this study, The basal serum level of calcitriol D3PTH, calcium[ca], phosphorus [p], creatinine, urea and albumin, also the basal urinary level of p, ca and creatinine were determined. The patients were subjected to special dietary regemen with restriction of p by giving special menus for 3 months, the level of the previously mentioned parameters were re-estimated. The p/creatinine index was used to evaluate the fulfilment of the diet. The basal level of PTH was 76.4 +/- 34 pg/ml [normal range 10-65], calcitriol was 21.6 +/- 3.4 pg/ml [normal range 20-45]. After dietary p restriction the mean level of PTH descended significantly, 74% of the patients showed reduction of PTH. The mean level of calcitriol rose significantly after the diet, all the patients showed an increase in their level. A moderate restriction of p in the diet has produced an improvement of the level of serum calcitriol, obtaining a level similar to that of healthy subjects, also reduction of the level of PTH has been obtained near the normal range. This diet represent an easy therapeutic maneuver and without cost In the way of prevention of secondary hyperparathyroidism and consequent osteodystrophy in patients with CRF

Clinical profile of 128 subjects operated for primary hyperparathyroidism

From 1960 to 1990, one hundred twenty eight (128) subjects with primary hyperparathyroidism were operated in the University Hospital. The medical records were reviewed. Serum and urine chemistries were done by conventional methods, serum PTH was done by RIA's (N-, C-, and midregion) and intact by IRMA and 1,25 dihydroxycholecalciferol by a non equilibrium receptor assay from calf thymus and preceded by double Sep-Pak chromatography. The distal third of the radius (nondominant arm) was used to evaluate radial bone density (RBD), using single photon absorptiometry (Norland) and the lumbar bone density (LBD) was measured by dual energy X Ray absorptiometry (DEXA). The RBD was done in 41 females and 15 males and the LBD in 12 females and 4 males. The series comprised 95 females, age range from 15 to 79 years, and 33 males, age range from 14 to 69 years. Prominent clinical features included nephrolithiasis in 72 subjects (56 per cent), osteitis fibrosa cystica in 2, isolated familial hyperparathyroidism in 4 subjects in one family, 7 subjects with MEN-1 in 3 families, and 4 subjects with MEN-2 in one family. Only 7 subjects were asymptomatic. Serum calcium was elevated in all, serum alkaline phosphatase was elevated in 24 per cent and urinary hydroxiproline was increased in 48 per cent. Serum phosphorus was low in 92 per cent. PTH assay was either elevated or inappropriately normal for the serum calcium in all patients tested. Serum 1,25 D was elevated in 57 per cent. The PTH level was positively correlated with the serum calcium (r = 0.70), but had no significant correlation with the serum phosphorus and the 1,25 D. The RBD expressed as the standard deviation from that of the mean for age and sex matched controls was > or = 2 SD below the mean in 39 per cent of females and in 40 per cent of males. In contrast to the RBD none of the subjects tested had a LBD > or = 2 SD below the age and sex adjusted mean. 103 subjects had adenomas, 20 primary hyperplasia, 2 carcinomas and in 3 surgical exploration was unsuccessful. As to the outcome of Surgery, 117 (93 per cent) were cured. Thus, in this series, successful surgery for primary hyperparathyroidism is the rule. Primary hyperparathroidism is rarely asymptomatic and appendicular bone disease and nephrolithiasis are commonly seen.

Serum parathyrin and calcitriol in insulin dependent diabetic subjects: effects of glyceric control

This work was conducted on 21 insulin dependent diabetic patients [IDDM] and 10 sex and age-matched normal controls. Fasting blood sugar [FBS], calcium [Ca], phosphorus [P], parathyrin [parathormone, PTH] and 1,25 [OH]2 Vit D3 [calcitriol] were estimated before and after glycemic control with insulin. Results revealed a significant decrease in total serum Ca, P, PTH and active Vit D in uncontrolled IDDM. Glycemic control of diabetic patients was accompanied by a significant increase in total serum Ca, PTH and calcitriol