Rubidium and potassium concentrations in human blood and urine

The naturally occurring rubidium and potassium concentrations wee measured in human plasma, erythrocytes and urine for normal, diseased and pregnant Utah subjects. The mean plasma Rb concentration in the normal adult subjects was 0.16 microgram/ml (y/ml) with a standard deviation (SD) of ±0.028 y/ml and the mean K concentration was 160 y/ml (±16.1 y/ml SD). The mean erythrocyte Rb concentration in the normal adult subjects was 1.18 y/ml (±0.623 y/ml SD) and the mean K concentration was 3840 y/ml (±142 y/ml SD). The mean urine Rb concentration in normal adult subjects was 1.52 y/ml (±0.549 y/ml SD) and the mean K concentration was 1910 y/ml (±581 y/ml SD). The Rb and K concentrations in the pregnant and diseased subjects did not vary significantly from the normal means. The mean estimated in Rb dietary intake rate for the normal adult subjects was 2.16 mg/d (±0.747 mg/d DS) and the estimated mean rate for K was 2.46 g/d (±0.040 g/d SD). The Adjusted Retentioin Ration (ARR), a ration of concentration ratios, was defined as AAR= (RB/K) Erythrocytes/(Rb/K)Excreta. The mean ARR for the normal adult subjects was 1.19 (±0.106 SD). A mean ARR > 1 indicates that Rb is preferentially retained in the erythrocyte compared to K when normalized for dietary intake. A subject with Duchenne muscular dystrophy had a ARR of 0.995 (±0.0694 SD). The estimated Rb whole-body burden in a normal 37 y old, 82 kg, 178 cm tall male was 0.28 g as calculated from 83Rb tracer measurements and the urine output rate of naturally occurring Rb. The Rb whole-body burden for a 15 y old, 69 kg, 140 cm tall male with Duchenne muscular dystrophy was 0.064 g.