A new approach to the assessment of marginal vitamin A deficiency in children in suburban Guwahati, India: hydrolysis of retinoyl glucuronide to retinoic acid

The objective of the present study was to determine marginal vitamin A deficiency (VAD) by testing the hydrolysis of retinoyl glucuronide (RAG) to retinoic acid (RA) in children. Previous studies in rats showed that hydrolysis occurred when rats were vitamin A deficient. Children (n 61) aged 3-18 years, were divided into two groups, I and II. Blood was collected from the children in Group I (n 19) who were not dosed with RAG. Children in Group 11 (n 42) were administered all-trans retinoyl glucuronide (RAG) orally, and blood was collected 4h after the dose. All serum samples were analysed for retinoids and carotenoids. RA was detected in serum only when serum retinol was <0.85 mu mol/l. Thus, hydrolysis of RAG to RA occurred in children with VAD or marginal VAD. Serum retinol wits <0-35 mu mol/l in twenty-one children, 0.35-0.7 mu mol/l in twenty-three children, 0.7-0.9 mu mol/l in eleven children and > 1 mu mol/l in six children. Mean serum retinol in sixty-one children was 0.522 (SD 0.315) mu mol/l. Mean beta-carotene (0-016 (SD 0.015) mu mol/l) was far below normal compared to the level of lutein (0-176 (SD 0.10) mu mol/l in sixty-one children. A low beta-carotene level might be due to a low intake of carotene but high demand for vitamin A. The RAG hydrolysis test may prove to be a useful approach for the determination of marginal VAD with no clinical or subclinical signs of VAD. High prevalence of VAD amongst certain communities in Assam cannot be ruled out.