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Assessment of marginal vitamin A deficiency in Brazilian children using the relative dose response procedure
Insights
The relative dose response (RDR) test is a sensitive indicator of vitamin A deficiency in young children. Supplementation with a massive oral dose of vitamin A improved RDR test results and serum iron levels.
Area of Science:
- Nutritional Science
- Public Health
- Pediatrics
Background:
- Assessing vitamin A status is crucial for child health, especially in low-income populations.
- Traditional methods may not accurately reflect marginal vitamin A deficiency.
- The relative dose response (RDR) procedure offers a functional assessment of vitamin A status.
Purpose of the Study:
- To evaluate vitamin A status in young children using plasma levels and the RDR procedure.
- To assess the impact of a massive oral vitamin A dose on vitamin A status and other biomarkers.
- To determine the sensitivity of the RDR test compared to serum vitamin A levels.
Main Methods:
- Conducted RDR tests and measured plasma vitamin A in 93 children (≤7 years) before and after a 200,000 IU oral vitamin A dose.
- Repeated RDR tests at 30, 120, and 180 days post-supplementation.
- Analyzed serum iron, hemoglobin, total protein, and albumin concurrently.
Main Results:
- Serum iron levels improved 30 days after vitamin A supplementation.
- The RDR procedure was practical for use in mildly undernourished children.
- Elevated RDR tests (indicating deficiency) were common when serum vitamin A was ≤20 µg/dL.
- RDR tests normalized post-supplementation, suggesting improved vitamin A status.
- RDR was more sensitive than serum vitamin A levels alone for detecting inadequacy when levels were >20 µg/dL.
Conclusions:
- The RDR test is a sensitive and practical method for identifying inadequate vitamin A status in young children.
- Massive oral vitamin A supplementation improved vitamin A status and serum iron levels in this cohort.
- RDR testing provides valuable functional information beyond static serum vitamin A measurements.
Abstract:
Vitamin A status was determined using fasting plasma levels and the relative dose response (RDR) procedure before and 30, 120, and 180 days after administration of an oral massive (200,000 IU) dose of vitamin A. The study was carried out in Recife, Brazil among 93 children of 7 yr or less from low income families who attended two day-care programs. The RDR procedure is conducted by obtaining a fasting blood (A0), feeding 450 retinol equivalents and obtaining a second blood specimen after 5 h (A5). The RDR-(A5-A0)/A5 X 100. A single massive oral dose of vitamin A was given after conducting the base-line RDR test. The RDR procedure was repeated at 30, 120, and 180 days. Weight and height measurements were obtained at each observation and the bloods were analyzed for Hb, total protein, and serum iron, as well as vitamin A. Serum albumin was determined in 120- and 180-day bloods. Serum iron levels were improved 30 days after supplementation with the massive dose of vitamin A. The RDR procedure was found practical to apply in mildly undernourished children under nonclinical condition. In this group of low income children presumed to be habitually ingesting minimally adequate diets, a serum vitamin A level of 20 micrograms/dl or less invariably was associated with an elevated RDR test. Blood levels between 20 to 40 micrograms/dl were not consistently predictive of the RDR response. All elevated RDR tests reverted to normal after supplementation with vitamin A, presumably indirectly indicating a presupplementation inadequate vitamin A status. Hence, the RDR was a more sensitive indicator of inadequate vitamin A status than was only a serum level of vitamin A when blood levels were above 20 micrograms/dl.(ABSTRACT TRUNCATED AT 250 WORDS)