Excretion of Vitamin A in Urine of Women during Normal Pregnancy and Pregnancy Complications

Abstract

Background/Aims: The renal function, including the excretion of low-molecular-weight proteins, changes during pregnancy and may cause a urinary excretion of retinol-binding protein (RBP). Whether it is accompanied by a substantial loss of vitamin A (retinol) has not been established yet. We therefore determined the excretion of retinol and RBP in urine of pregnant women. Methods: The study involved analyses of urine samples from 40 healthy pregnant women and 29 women with pregnancy complications during the third trimester. Analyses of plasma and urine of 7 healthy women and 5 women with pregnancy complications were also carried out 6 weeks antepartum, at time of delivery and 1 week postpartum. Results: Urinary retinol was higher in women who suffered from pregnancy disorders with an influence on maternal metabolism (p < 0.01). RBP was excreted at substantial concentrations in the urine of all 69 women, but there were no differences between the groups. Women with a concomitant excretion of retinol had higher levels of urinary RBP than those without a retinol excretion (p < 0.05). Differences in plasma retinol and RBP were not significant. Conclusion: The excretion of urinary retinol may increase significantly during pregnancy complications, which needs further clarification to which extent this condition may negatively affect the vitamin A status in such women.