Oral administration of radioactive sulfate to measure extracellular fluid space in man.
Radioactive sulfate-35 (35S) was administered to eight human subjects intravenously and orally, to compare respective kinetics of distribution. Intravenously administered 35S attained equilibration within 60-90 min. Orally administered 35S attained equilibration within 60-105 min and thereafter achieved plasma activity equivalent to the intravenously administered tracer. Eighty percent or greater of the 35S dose was recovered in the 24-h urine, following either intravenous or oral administration. The mean extracellular fluid space demonstrated less than 9% mean difference between routes of administration. It is concluded that 35S is completely absorbed at tracer doses, and may be administered orally as a reliable substitute for intravenously administered 35S for measuring extracellular fluid space.
D000284:Administration, Oral; D005110:Extracellular Space / Q000032:analysis*; D006801:Humans; D007275:Injections, Intravenous; D013431:Sulfates / Q000008:administration & dosage / Q000378:metabolism*; D013462:Sulfur Radioisotopes; D013997:Time Factors
D013431:Sulfates; D013462:Sulfur Radioisotopes