Renal clearance of amino acids in pregnancy complicated by preeclampsia.

Renal clearance of most amino acids was increased in the third trimester of pregnancy. The greatest change was with glycine, where clearance increased thirteen-fold and the plasma level decreased. No difference in renal clearance of amino acids was demonstrated in four patients with proteinuric hypertension when compared with that in normal pregnancy. Progesterone, given to non-pregnant women, caused a fall in mean plasma glycine. This was associated with increased renal clearance in 2 out of 3 women, and indicates that progesterone may contribute to the increased renal excretion of some amino acids in pregnancy, probably acting selectively on tubular reabsorption.