Vitamin D status in primary hyperparathyroidism in India

Primary hyperparathyroidism is a syndrome with variable clinical expression, presenting as asymptomatic hypercalcaemia in Western countries and with predominant bone disease in developing countries. Vitamin D deficiency has been implicated as the cause of bone disease. There is a paucity of information on the vitamin D (25-OHD3) status of patients with primary hyperparathyroidism presenting with bone disease. The present study aims to evaluate the vitamin D status in patients with primary hyperparathyroidism and to correlate it with the bone disease.

Twenty consecutive patients with primary hyperparathyroidism admitted to the endocrinology and metabolism wards of the All India Institute of Medical Sciences were analysed to assess their clinical, radiological and biochemical features, as well as parathyroid hormone (mid-molecular, PTH-MM) and 25-OHD3 levels.

PTH-MM levels and 25-OHD3 levels were measured using RIA kits.

Bone disease (osteitis fibrosa cystica) was the mode of presentation in 90%. Radiologically, sub-periosteal resorption was present in 90% of the total group of patients, brown tumours in 60%, and pathological fractures in 40%. Renal stones and/or nephrocalcinosis was present in 50% of patients. Mean serum calcium, phosphate and alkaline phosphatase concentrations (mean of 3 days values) were 2.72 +/- 0.24 mmol/l; 1.01 +/- 0.28 mmol/l and 425 +/- 249 IU/l respectively. The 24-hour (mean of 3 days values) urine calcium and phosphate excretions were 8.0 +/- 4.2 mmol and 19.0 +/- 13 mmol. Only 50% of the patients had hypercalcaemia ( > 2.7 mmol/l). However, 90% of the whole group of patients had hypercalciuria. The mean serum creatinine concentration of patients with hypercalcaemia was 108 +/- 38 mumol/l and of those with normocalcaemia 89 +/- 33 mumol/l. The mean serum PTH-MM was 438 +/- 350 pmol/l (the detection limit for the kit was 34 pmol/l). Ultrasound examination detected adenomas in 72% of the cases and computerized tomography of the neck localized adenomas in 71% of the cases. The median weight of the adenoma was 4.6 g (range 0.125-25 g). Two patients had coexistent hyperplasia of the other parathyroid glands and two had recurrent adenomas. 25-OHD3 levels were assessed in all 20 patients under fasting conditions. The mean value of 25-OHD3 observed (8.4 +/- 5.1 micrograms/l) was comparable to the mean value measured in 14 healthy age and sex matched controls (8.3 +/- 2.5 micrograms/l).

Patients with primary hyperparathyroidism in India presented with bone and renal diseases; half were normocalcaemic. All the patients had hypercalciuria despite the bone disease. The PTH-MM levels were increased and 25-OHD3 levels were low. The predominant bone disease is probably due to prolonged primary hyperparathyroidism coexisting with low calcium intake and/or 25-OHD3 deficiency. The mean weight of the adenoma was higher than that reported for patients in the Western literature.