Prevalence of hypovitaminosis D and secondary hyperparathyroidism in postmenopausal women

Abstract

Introduction: Vitamin D and parathyroid hormone (PTH) are two major modulators of mineral metabolism and the maintenance of calcium and phosphorus homeostasis. Vitamin D insufficiency is characterized by serum 25-hydroxy-vitamin D [25(OH)D] concentration under 30 ng/mL and deficiency under 20 ng/mL. Such deficiency also increases PTH secretion and bone demineralization. This study aims to evaluate serum 25(OH)D concentrations in postmenopausal women and correlate them with serum PTH concentrations and bone mineral density (BMD). Methods: Clinical, laboratorial and densitometric data were collected from 114 postmenopausal women who participated in a previous clinical study. The patients recruited had a diagnosis of osteopenia or osteoporosis without previous treatment. Statistical analysis was carried out by the Statistica-Statsoft® software. Results: Patients were divided in osteoporotic 82.9% (n = 92) and osteopenic 17.1% (n = 19). The mean values ​​of 25(OH)D found were 26.21 ± 9.69 ng/mL. Deficiency (16.05 ± 2.81 ng/mL) was identified in 32,4% of patients (n = 37) and insufficiency (24.71 ± 3.18 ng/mL) in 33,3% (n = 38). PTH ​​presented a mean of 53.7 ± 20.1 pg/mL and 25% (n = 29) were above the reference values. Concentrations of PTH correlated inversely with 25(OH)D (p < 0,01; rho = -0,2971). There was a negative correlation of femoral neck T-score in two situations: history of fractures and diagnosis of spinal fractures (p < 0,01). Conclusion: Hypovitaminosis D has been shown to be prevalent among these post menopausal women with no seasonal influence. There was a negative correlation between PTH levels and 25(OH)D. A correlation between the history of fractures and BMD was found, therefore, femur BMD can predict risk of fractures in other sites.