The long-term excretion and retention of an intravenous dose of 45Ca in two healthy men
Carr, T.E.; Harrison, G.E.; Nolan, J.
Calcified Tissue Research 12(3): 217-226
1973
ISSN/ISBN: 0008-0594 PMID: 4747565 Document Number: 64805
Two normal men aged 47 and 66 years on normal diets were given 3 mu Ci 45Ca in saline by injection into an antecubital vein 1 h after breakfast. Blood was sampled from the antecubital vein in the other arm 10 min, 2 and 5 h, 1, 2, 4, 7, 11 and 15 days after the injection. Daily collections of excreta ceased at 23 days and were resumed intermittently from 36 days for periods of 14 to 18 days at different times up to 388 days. Mean renal clearance from 1 to 15 days for the 2 men was 3.4 plus or minus 0.1 and 3.5 plus or minus 0.1 litre/day; the difference was not significant. Excretion rates of 45Ca in urine were similar for the 2 men but excretion rates in faeces differed by a factor of 2. Retention (R), expressed as dose less excretion, was plotted against the time (t) after the dose on logarithmic scales. The relation between log R and log t consisted of a curve up to 30 or 50 days and then of a linear relation up to 388 days. The straight line resulted from a power law relation between R and t.