Seasonal Variations in Urinary Calcium and Oxalate in Normal Subjects and Patients with Idiopathic Hypercalciuria

Abstract

Remarkable seasonal changes in urinary calcium of patients with idiopathic calcium stones were reported from Leeds by Robertson et al (1974 & 75) who found mid-summer and mid-winter values of 9.3 and 5.7 mmol/per 24 hour respectively. These results seemed somewhat surprising and it was therefore decided to see if they could be confirmed in London. To this end two separate studies were carried out. In a 9 year retrospective study, the records were examined of patients with idiopathic hypercalciuria who had repeatedly attended a single metabolic stone clinic. Many of the patients had been seen first untreated and then treated with Thiazide diuretics or cellulose phosphate, or both, and it was possible to sub-divide the data according to treatment. The second study was prospective and based upon a small group of normal volunteers each of whom collected a 24h urine sample every month for 13 consecutive months.