RESUMO
There is considerable interest in whether a defect in renal sodium handling is important in the development of essential hypertension. A recent report indicated that the proximal tubule might be involved, since fractional lithium clearance, a measure of the fraction of filtered sodium reaching the end of the proximal tubale, was reduced in hypertentive patients. However, ther were a number of objectionable points in that paper. In the present study, we measured clearances of creatinine (C cr), lithium, (C li) and sodium (C na) in 21 hypertensive patients and 21 controls matched for age, sex and ethnic background. Clearances were measured over a 4-h period during which the subject were seated. The result provide no evidence for altered proximal tubular sodium handling in essential hypertension under the conditions of the study.