Assessment of vitamin A status in pregnant women as reflected by in vitro destruction of vitamin A by hemolysates and urinary ammonium nitrogen to creatinine ratio.

To investigate the significance of the lowered plasma vitamin A during the last few weeks of pregnancy, the capacity of erythrocyte lysates to destroy vitamin A in vitro and the alteration in ammonium nitrogen to creatinine ratio (Am N/Cr) in random urine samples was followed up at different gestational ages in women from low income groups. One group received no supplementation and the other received supplements of 1800 retinol equivalents (RE) and at most points the number of observations were not less than 12. In the unsupplemented women there was a significant increase in the capacity of erythrocytes to destroy vitamin A in vitro, which reflects an increased oxidative stress as compared to the supplemented group. While differences in mean Am N/Cr did not follow any consistent pattern, there was a strong association between lowered plasma vitamin A (< 35 micrograms/dl) and increased Am N/Cr ratio (> 0.5). This was true only when combined data of both groups were considered till 26 weeks of gestation and not beyond. As expected in supplemented women there was no significant fall in the plasma vitamin A during term. These data reveal that the lowered plasma vitamin A levels are suggestive of greater risk of hypovitaminosis A during pregnancy as indicated by the oxidative stress in erythrocytes.