Relationship between serum vitamin d status and clinical manifestations of primary hyperparathyroidism

To compare vitamin D status represented by serum 25-hydroxyvitamin D (25-OHD) levels in a group of patients with primary hyperparathyroidism, stratified by clinical manifestations.

We studied 22 patients (18 women and 4 men) with primary hyperparathyroidism--5 patients with severe osteitis fibrosa cystica, 10 symptomatic patients with active renal stone disease without overt bone disease, and 7 asymptomatic patients. Bone mineral density (BMD) measurements (T-scores) were done at the lumbar spine, femoral neck, and distal radius, and laboratory data for the three subgroups were analyzed.

Although considerably younger than the asymptomatic group, patients with osteitis fibrosa had significantly lower mean serum 25-OHD levels (16.7 +/- 1.1 ng/mL versus 29.9 +/- 2.9 ng/mL; P = 0.003). Moreover, patients with osteitis fibrosa had significantly lower BMD in comparison with patients who had renal stone disease as well as asymptomatic patients for all sites measured. Serum parathyroid hormone levels were significantly higher in patients with osteitis fibrosa than in asymptomatic patients (1,352.8 +/- 297.2 pg/mL versus 145.0 +/- 43.7 pg/mL; P<0.02) as well as in comparison with patients who had renal stone disease (P<0.02). Patients with osteitis fibrosa had urinary N-telopeptide levels that were significantly higher than those in asymptomatic patients (501.5 +/- 201.7 versus 51.3 +/- 6.4 nmol/mmol creatinine; P = 0.02) and those in patients with renal stone disease (P = 0.01).

The findings in this study demonstrate that vitamin D deficiency or insufficiency may contribute to disease severity in primary hyperparathyroidism.