Secondary hyperparathyroidism in primary osteoporosis and osteopenia: optimizing calcium and vitamin D intakes to levels recommended by expert panels may not be sufficient for correction

Summary Objective To compare biochemical variables, renal function and calcium and vitamin D intakes in euparathyroid and hyperparathyroid patients with primary osteoporosis and osteopenia and describe the measures necessary to normalize serum PTH in the patients with secondary hyperparathyroidism. Design and patients We reviewed the charts of normocalcemic patients with primary osteoporosis and osteopenia first seen during the years 1991–2003 and identified 75 with elevated serum PTH levels at baseline. These patients were compared to all the 143 euparathyroid patients first seen in 1998 and 1999. Patients were restudied after 1 year and we attempted to follow patients with secondary hyperparathyroidism until PTH levels became normal. Measurements At baseline serum PTH, ionized calcium, inorganic phosphate, alkaline phosphatase, creatinine, a complete blood count and serum 25 hydroxy vitamin D were measured in the early morning fasting state. These tests were repeated at follow up. Results In one-third of the hyperparathyroid patients, the standard baseline treatment failed to correct the secondary hyperparathyroidism necessitating extraordinary measures including unusually large doses of vitamin D (i.e. 50 000 IU vitamin D2 twice weekly) or the substitution of calcium citrate for calcium carbonate as a calcium supplement. Conclusion Large doses of vitamin D are frequently necessary to suppress secondary hyperparathyroidism in patients with primary osteoporosis and osteopenia. This suggests that vitamin D metabolism may be altered in some of these patients.