Vitamin D supplementation in primary hyperparathyroidism: effects on 1,25(OH)2 vitamin D and FGF23 levels.

PURPOSE: In patients with Primary Hyperparathyroidism (PHPT) vitamin D deficiency has been associated with more severe presentations. Our aim was to investigate the effects of Vitamin D supplementation on mineral homeostasis and related hormones in individuals with and without PHPT. METHODS: Individuals with and without PHPT (CTRL) received 14,000 IU/week of oral vitamin D3 for 12 weeks. At baseline and endpoint, blood samples were collected to measure 1,25(OH)2vitamin D (1,25(OH)2D), intact Fibroblast Growth Factor 23 (FGF23), 25OHD, Parathormone, and other biochemical markers. The 1,25(OH)2D measurement was performed using liquid chromatography and mass spectrometry (LC-MS/MS). RESULTS: 70 PHPT patients and 75 CTRL were included, and 55 PHPT and 64 CTRL completed the 12-week protocol. After the intervention, there were significant increases in the FGF23 levels (PHPT: 47.9 ± 27.1 to 76.3 ± 33.3; CTRL: 40.5 ± 13.9 to 59.8 ± 19.8 pg/mL, p < 0.001), and significant decreases in 1,25(OH)2D levels (PHPT: 94.8 ± 34.6 to 68.9 ± 25.3; CTRL: 68.7 ± 23.5 to 56.4 ± 20.7 pg/mL, p < 0.001). The reduction of 1,25(OH)2D was inversely associated with the increase of FGF23 in both the PHPT (r = -0.302, p = 0.028) and CTRL (r = -0.278, p = 0.027). No changes in plasmatic or uninary calcium concentrations were observed in both groups. CONCLUSION: The weekly administration of 14,000 IU of Vitamin D3 was safe and efficient to increase in 25OHD levels in both groups. However, a paradoxical decrease in 1,25(OH)2D levels measured by LC-MS/MS was associated with a significant increase in FGF23 levels in both groups. This phenomenon might represent a defense against hypercalcemia after vitamin D supplementation and paves the way for new studies in this regard.

COPD as an independent risk factor for osteoporosis and fractures.

Fractures are common in individuals with COPD and occur at higher bone mass values than expected. COPD appears to be an important risk factor for bone fragility. INTRODUCTION: Patients with chronic obstructive pulmonary disease (COPD) have an increased risk of osteoporosis and fractures, but screening and prophylactic measures to prevent both disorders are often neglected in this population. This case-control study assessed the prevalence of osteopenia, osteoporosis, and fractures in patients with COPD, and identified potential risk factors for fractures in this population. METHODS: Overall, 91 patients with COPD (COPD group; COPDG) and 81 age- and sex-matched controls (control group; CG) were assessed with bone mineral density (BMD), thoracic/lumbar spine radiographs, and serum PTH and 25-hydroxyvitamin D (25[OH]D) levels. The occurrence of prior fractures was retrieved from clinical history. RESULTS: The prevalence of total fractures in the COPDG was 57.1% (odds of fracture 4.7 times greater compared with the CG), and the femoral neck T-score emerged as the best predictor of fractures. Compared with the CG, the COPDG had lower spine and femoral BMD (p ≤ 0.01) and 25(OH)D levels (p = 0.01) and 2.6 times greater odds of osteoporosis. Among men, vertebral fractures were more prevalent in the COPDG versus CG (25.9% vs. 6.5%, respectively, p = 0.01). The odds of fracture increased with femoral neck T-scores ≤ - 2.7 in the CG and ≤ - 0.6 in the COPDG. CONCLUSION: These results add robust evidence to an increased odds of osteoporosis and fractures in COPD. Fractures in the COPDG occurred at higher BMD values than expected, suggesting that COPD may be an independent marker of fracture risk, reinforcing a need for regular osteoporosis screening with BMD measurement and prophylaxis of fractures in patients with this disorder.

The effect of sun exposure on 25-hydroxyvitamin D concentrations in young healthy subjects living in the city of São Paulo, Brazil

The range of 25-hydroxyvitamin D (25OHD) concentration was determined in a young healthy population based on bone metabolism parameters and environmental and behavioral aspects. We studied 121 healthy young volunteers (49 men, 72 women) living in São Paulo (23º 34' south latitude) belonging to three occupational categories: indoor workers (N = 28), medical school students (N = 44), and resident physicians (N = 49). Fasting morning blood samples were collected once from each volunteer from August 2002 to February 2004, and 25OHD, total calcium, albumin, alkaline phosphatase, phosphorus, creatinine, intact parathyroid hormone, osteocalcin, and type I collagen carboxyterminal telopeptide were measured. Data are reported as means ± SD. Mean subject age was 24.7 ± 2.68 years and mean 25OHD level for the entire group was 78.7 ± 33.1 nM. 25OHD levels were lower (P < 0.05) among resident physicians (67.1 ± 27.0 nM) than among students (81.5 ± 35.8 nM) and workers (94.0 ± 32.6 nM), with the last two categories displaying no difference. Parathyroid hormone was higher (P < 0.05) and osteocalcin was lower (P < 0.05) among resident physicians compared to non-physicians. Solar exposure and frequency of beach outings showed a positive association with 25OHD (P < 0.001), and summer samples presented higher results than winter ones (97.8 ± 33.5 and 62.9 ± 23.5 nM, respectively). To define normal levels, parameters such as occupational activity, seasonality and habits related to solar exposure should be taken into account. Based on these data, we considered concentrations above 74.5 nM to be desired optimal 25OHD levels, which were obtained during the summer for 75 percent of the non-physicians.

The effect of sun exposure on 25-hydroxyvitamin D concentrations in young healthy subjects living in the city of São Paulo, Brazil.

The range of 25-hydroxyvitamin D (25OHD) concentration was determined in a young healthy population based on bone metabolism parameters and environmental and behavioral aspects. We studied 121 healthy young volunteers (49 men, 72 women) living in São Paulo (23 masculine 34' south latitude) belonging to three occupational categories: indoor workers (N = 28), medical school students (N = 44), and resident physicians (N = 49). Fasting morning blood samples were collected once from each volunteer from August 2002 to February 2004, and 25OHD, total calcium, albumin, alkaline phosphatase, phosphorus, creatinine, intact parathyroid hormone, osteocalcin, and type I collagen carboxyterminal telopeptide were measured. Data are reported as means +/- SD. Mean subject age was 24.7 +/- 2.68 years and mean 25OHD level for the entire group was 78.7 +/- 33.1 nM. 25OHD levels were lower (P < 0.05) among resident physicians (67.1 +/- 27.0 nM) than among students (81.5 +/- 35.8 nM) and workers (94.0 +/- 32.6 nM), with the last two categories displaying no difference. Parathyroid hormone was higher (P < 0.05) and osteocalcin was lower (P < 0.05) among resident physicians compared to non-physicians. Solar exposure and frequency of beach outings showed a positive association with 25OHD (P < 0.001), and summer samples presented higher results than winter ones (97.8 +/- 33.5 and 62.9 +/- 23.5 nM, respectively). To define normal levels, parameters such as occupational activity, seasonality and habits related to solar exposure should be taken into account. Based on these data, we considered concentrations above 74.5 nM to be desired optimal 25OHD levels, which were obtained during the summer for 75% of the non-physicians.