Red blood cell sodium-lithium countertransport, blood pressure, and uric acid metabolism in untreated healthy men

The relationship of red blood cell (RBC) Na/Li countertransport to the renal handling of lithium and uric acid was investigated in a sample of 176 untreated men. Subjects in the upper quintile of the Na/Li countertransport distribution (n = 40), compared to those in the two lower quintiles (n = 72), had higher serum uric acid levels (0.34 ± 0.06 ν 0.29 ± 0.05 mmol/L, P ` 0.001) and systolic blood pressure (131 ± 19 ν 123 ± 16 mm Hg, P ` 0.02) and slightly lower fractional excretion of uric acid (7.5 ± 1.5 ν 8.4 ± 2.6%, P ` 0.08). The lithium fractional excretion was not significantly related to either blood pressure or R B C Na/Li countertransport. The altered uric acid metabolism in individuals with high RBC Na/Li countertransport could be the expression of an abnormality of renal tubular function. Am J Hypertens 1989; 2: 634-636.