Tyrosine Tolerance Test in Pregnancy and the Puerperium.∗

Conclusions 1. The fasting blood tyrosyl level is significantly lowered during normal pregnancy, but not in the puerperium. 2. The reduced tyrosine tolerance curve during pregnancy suggests an increased rate of metabolism for this amino acid. There is an immediate reversal of this effect after delivery. 3. Unlike histidine. the renal tubular reabsorption of tyrosine appears to be as complete in pregnant as in non-pregnant subjects. 4. No alterations in tyrosine tolerance were noted in a case of preeclampsia nor in a case of eclampsia. 5. The observed shifts in tyrosine metabolism, possibly concerned with similar shifts in rates of protein synthesis, would probably invalidate the tyrosine tolerance test as a measure of liver function in pregnant and puerperal women.