[Various biochemical functions of the renal tubules and glomeruli in women during normal pregnancy and the puerperium].

The study was carried out in 194 healthy women, including 50 non-pregnant, 31 pregnant in the 1st trimester, 32 in the 2nd and 30 in the 3rd trimester, and 51 in the 3rd day of puerperium. Their age was 19-43 years, they gave no history of renal disease nor urinary tract disease. The biochemical tests evaluating the function of renal tubules and glomeruli were done in 24-hour urine: 1) 24-hour urine volume, 2) NH4+, 3) H+, 4) K+ and 5) Na+ ions. Endogenous creatinine clearance was determined as well in all cases. The results were subjected to statistical analysis. Increased tumular metabolism of carbonic acid begins in the 16th week of pregnancy, increases further till the end of pregnancy and is still high on the 3rd day of puerperium. Amino acid metabolism increase in the tubules was noted only in the 3rd trimester of pregnancy, and it was normal again on the 3rd day of the puerperium. K+ and Na+ excretion was raised in the 3rd trimester, and on the 3rd day postpartum potassium excretion was still high while that of sodium was normal. Endogenous creatinine clearance rose in the 2nd and 3rd trimesters and failed to return to the value before pregnancy on the 3rd day postpartum. The observed changes in the biochemical functions of renal tubules and glomeruli in physiological pregnancy may be responsible for the typical changes of blood acid-base equilibrium in pregnancy (compensated metabolic acidosis with respiratory alkalosis).