Relation between hypercalciuria and vitamin D3-status in patients with urolithiasis.

Patients with urolithiasis were divided into two groups, one (n = 38) with a urinary excretion of calcium exceeding 6.0 mmol/24 h and one (n = 32) with a calcium excretion lower than 6.1 mmol/24 h. The group of patients with a high urinary excretion of calcium had a significantly higher level of 25-hydroxy vitamin D3 (26.2 +/- 1.6 ng/ml) than had the group of patients with a normal urinary excretion of calcium (17.6 +/- 0.9 ng/ml) (p less than 0.001). A highly specific and accurate method, based on isotope dilution--mass spectrometry was used in the assay of 25-hydroxy vitamin D3. There was no over-all correlation between level of 25-hydroxy vitamin D3 and serum level of calcium (r = 0.1). The results are in accordance with the contention that the vitamin D3-status might be of some importance for the development of hypercalciuria in these patients.