The Excretion of Calcium in the Urine and its Relation to Calcium Intake, Sex and Age

Abstract

S U M M A R Y1. Until recently estimates of the urinary excretion of calcium have largely been based upon studies of patients in hospital and, consequently, with changes in the person's diet and physical activity.2. We have measured the urinary excretion of calcium in seventy-five men and ninety-eight women aged 20-69 years, who were all apparently healthy and who were taking their chosen free diet.3. For 7 consecutive days each person recorded the weight of all food that was eaten and collected 24 h specimens of urine. We have examined in these persons the relation between the urinary calcium, the dietary intake of calcium, age and sex.4. 95% of the men excreted less than 400 mg of calcium in the urine per day and 95% of the women excreted less than 340 mg/day. 5.Within the limits of the calcium intake (mean values: men 1148 mg/day, women 1042 mg/day) found in this study, there was no relationship between the dietary calcium and the urinary excretion of calcium except in men over the age of 50 years. Even then the regression accounted for only a minor part of the variation in urine calcium.6. The urinary excretion of calcium diminished in men over the age of 60 and in women over the age of 50 years. 7. These results arediscussed in relation to previous studies of the urinaryexcretion of calcium. It is concluded that the urinary excretion of calcium is determined more by the absorption of calcium from the intestine than by the intake of calcium, and that the efficiency of absorption decreases in men and women as they grow older.The daily excretion of calcium in the urine is measured in the investigation of a variety of clinical conditions, in particular in a search for hypercalciuria as an aetiological factor in recurrent renal calculi. The range of urinary calcium which has been taken as a standard

Bone and ageing.

“…6 negative correlation between age and the urinary excretion of calcium, phosphorus, and total hydroxyproline in women is shown (Dequeker, 1972a). Saleh and Coenegracht (1969), Davis, Morgan, and Rivlin (1970), and Bulusu, Hodgkinson, Nordin, and Peacock (1970) found the same decrease inexcretion of calcium, phosphorus, or total hydroxyproline with age also in men. The decrease ofcalcium excretion with advancing age can be explained by a reduced intestinal absorption of calcium since it occurs in spite of the same calcium intake (Caniggia, Gennari, Bianchi, and Guideri, 1963;Avioli, Mcbonald, and Lee, 1965;Bullamore, Gallagher, Wilkinson, Nordin, and Marshall, 1970).…”

Distal Convoluted Tubule

“…Studies in normal humans have shown that males display a greater degree of urinary Ca 2+ excretion than females (94, 342). These observations indicate that sex steroid hormones may play a role in regulating the transcellular pathway.…”

Bioavailability of Minerals and Trace Elements

“…Increased efficiency of absorption is observed with vitamin D excess, Ca deficiency, phosphorus deficiency, pregnancy, lactation and certain disease states such as hyperparathyroidism, sarcoidosis and idiopathic hypercalciuria. Faecal excretion (incomplete absorption, desquamation and losses in digestive secretions) may account for up to 80 YO of the overall dietary Ca intake while urinary excretion is lower, between 10 and 35 YO of the intake (Davis et al 1970). …”