Vitamin D Status Affects Osteopenia in Postmenopausal Patients with Primary Hyperparathyroidism

Abstract

Controversy still exists about whether vitamin D status is related to the severity of primary hyperparathyroidism (pHPT), although vitamin D insufficiency is frequent in pHPT. The present study was therefore performed to examine the relationships between vitamin D status and various parameters in 30 postmenopausal pHPT patients. BMD values were measured by dual-energy x-ray absorptiometry at the lumbar spine (L_2-4), femoral neck (FN) and distal one third of the radius (Rad 1/3). Serum levels of 25 hydroxy-vitamn D₃ [25(OH)D] and 1,25-dihydroxy vitamin D₃ [1,25(OH) ₂D₃] were 15.8 ± 3.5 μg/l and 69.3 ± 33.3 ng/l in pHPT patients, respectively. Serum levels of calcium and PTH seemed to be negatively correlated to serum 25(OH)D levels, although the differences were not significant. However, when subjects with the highest serum PTH levels (PTH>1000 pg/ml) were excluded from the analysis, the correlation was significant between serum 25(OH)D levels and PTH, indicating that vitamin D status affects the severity of pHPT when severe cases were excluded. In addition, serum levels of 1,25(OH)₂D₃ were significantly and negatively correlated to serum 25(OH)D levels. On the other hand, serum levels of 25(OH)D were significantly and positively correlated to BMD (Z-score) at the lumbar spine, but not at the radius and femoral neck; however, serum 25(OH)D levels were not correlated to the levels of any bone metabolic indices measured. Moreover, serum levels of 25(OH)D were not related to urinary calcium and the tubular reabsorption rate of phosphorus, and they were similar in groups with and without renal stones. In conclusion, vitamin D status seemed to be related to the severity of disease in postmenopausal patients with pHPT. In particular, the relationship between serum 25(OH)D level and BMD at the lumbar spine was predominant.