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The modified relative dose response (MRDR) test value predicts liver vitamin A reserves in a piglet model
Author(s) -
Valentine Ashley Rebecca,
Surles Rebecca L,
Tanumihardjo Sherry A
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a353-b
Subject(s) - retinol , medicine , vitamin , endocrinology , malnutrition , gastroenterology , physiology
The modified relative dose response (MRDR) test is an indicator of vitamin A (VA) status when defined by hepatic VA. Debate exists as to how accurately the MRDR test reflects hepatic VA or a change in VA status. We examined the MRDR test and serum retinol as indicators of hepatic VA in piglets using the following values to indicate deficient or marginal status: ≥ 0.060, < 0.70 μmol/L, and < 30 retinol equivalents/g, respectively. In piglets ( n = 100) with a 78% prevalence of deficiency, the negative predictive value and sensitivity are higher using the MRDR test than serum retinol. The MRDR test more accurately indicated a change in VA status in groups of animals receiving supplementation than serum retinol. Serum retinol remains under homeostatic control throughout a wide range of liver values, but can be depressed due to protein‐energy undernutrition, iron and zinc deficiency, and the acute‐phase response even if hepatic VA is unaffected. Alternatively, the MRDR test reflects normal through severely depleted hepatic VA and is less affected by the acute‐phase response and mild to moderate protein‐energy undernutrition. Serum retinol and the MRDR test are correlated when hepatic VA is extremely low and when hepatic VA is ample. However, in groups with marginal status, the indicators are not correlated and the MRDR test gives a better definition of overall VA status. Supported by NIHNIDDK 61973 and USDA NRI 2003‐35200‐13754.