THE MEASUREMENT OF EXCHANGEABLE POTASSIUM IN MAN BY ISOTOPE DILUTION 1

Abstract

The theoretical and practical considerations pertaining to the measurement of the body content of K using K42 as atracer isotope are discussed. An isotonic soln. of K42 was injected intraven. and the specific activity of urinary K samples collected after 40-60 hrs. detd. The exchangeable K of 30 young male subjects was 2770-4040 meq. (37.0-57.1 meq.Ag-body wt.). Correlations between exchangeable K, body wt., surface area, basal O2 consumption, thiocyanate volume, total body water, plasma volume and urine creatinine are presented. Data concerning rabbit carcass K content, the rates of tissue and red blood cell K exchange, and rates of excretion, concns. and source of human urinary K are presented.