Correlations between Vitamin D Status and Biochemical/Clinical and Pathological Parameters in Primary Hyperparathyroidism

Background To determine the prevalence of vitamin D deficiency and the effects of vitamin D status on parathyroid adenoma weight, clinical and biochemical indices in patients with primary hyperparathyroidism (pHPT) were studied. Methods Eighty patients with pHPT who underwent surgical treatment and in whom the presence of parathyroid adenoma were confirmed histopathologically were studied retrospectively from recorded data files. Patients were divided into three groups: patients with 25‐hydroxyvitamin D (25‐OHD) concentrations < 15 ng/ml (group 1, n = 44), patients with 25‐OHD concentrations > 15–25 ng/ml (group 2, n = 9), and patients with 25‐OHD concentrations > 26 ng/ml (group 3, n = 27). Serum calcium, phosphate, alkaline phosphatase, creatinine, and albumin levels and urinary calcium excretion were determined by auto‐analyzer. Plasma 25‐OHD and parathyroid hormone (PTH) levels were determined by immunoradiometric assay using commercially available kits. Results No statistically significant differences were observed with respect to serum calcium, phosphorus, albumin, and creatinine concentrations between these groups. Serum PTH, alkaline phosphatase concentrations, urinary calcium excretion, parathyroid adenoma weight, and postoperative sixth month PTH concentrations were significantly higher in group 1 patients than in group 2 and group 3 patients. Significant correlations were observed between parathyroid adenoma weight and serum 25‐OHD concentrations (r = −0.348, P = 0.020); parathyroid adenoma weight and urinary calcium excretion (r = 0.348, P = 0.021). Multiple regression analysis revealed that parathyroid adenoma weight, serum 25‐OHD, and preoperative PTH concentrations correlated independently and significantly with postoperative sixth month PTH concentrations. Conclusions Vitamin D deficiency leads to more severe bone disease, increased parathyroid tumor growth, and delayed postoperative recovery of parathyroid function in patients with primary hyperparathyroidism.