Laboratory Distinction between Essential and Secondary Hypertension by Measurement of Erythrocyte Cation Fluxes

An abnormally low sodium-potassium net flux ratio in erythrocytes was recently described in human essential hypertension. We have confirmed this finding in 65 patients with essential hypertension who were compared with 33 normotensive controls born of normotensive parents. In 23 other subjects with documented secondary hypertension and normotensive parents, the sodium-potassium net flux ratio was found to be similar to that in the controls. The erythrocyte test thus appears to be of interest in distinguishing between essential and secondary hypertension. Severe renal failure itself reduces the flux ratio and would therefore distort the results of this test.