Renal excretion of calcium in healthy persons

The authors examined the calcium excretion in a group of 100 healthy subjects (50 men and 50 women) aged 21-40 years. Urine was collected under ambulatory conditions. Calcium excretion was expressed as Ca excretion per minute, Nordin's index, calciuria/GF.1.73 m2 and the renal threshold for calcium. Calcium excretion per minute was significantly lower in women, as compared with men. This significant difference of mean values of calcium excretion per minute persists when the subjects are classified by sex and age groups. Women aged 31-40 years had a significantly lower calciuria/GF.1.73 m2 than men aged 21-30 years and a significantly higher renal threshold for calcium, as compared with men of equal age. If standard conditions of urine collection are respected, the mentioned examination method can be used during ambulatory examinations of patients with impaired calcium and phosphate metabolism. The assessed values of different indicators must be, however, compared with values of healthy subjects of the same age and sex.