Use of the modified relative dose response (MRDR) assay in rats and its application to humans for the measurement of vitamin A status

S. A. Tanumihardjo, H. C. Furr, J. W. Erdman, J. A. Olson

Research output: Contribution to journalArticlepeer-review

Abstract

After an appropriate dose of 3,4-didehydroretinol (vitamin A2, DR) is given orally in corn oil to retinol (R)-depleted rats, the ratio of plasma DR/R values at 3.5 h is inversely related to the liver concentration of vitamin A (Tanumihardjo and Olson, 1988). In the present study, a similar procedure, termed the modified relative dose response (MRDR) assay, was employed with rats containing a much broader range of liver reserves; ie, < 2 to 107 nmol of vitamin A per g wet weight of liver (< 1 to 30 μg/g). The DR/R ratio for 15 of 16 rats with liver reserves < 17 nmol/g (< 5 μg/g) was > 0.15, whereas the ratio was < 0.15 for 7 of 8 rats with liver reserves > 17 nmol/g. This distribution provides sensitivity, specificity and positive predictive values of 94, 88 and 94 per cent, respectively. The DR/R ratios reached a maximal plateau in two other groups of rats between 3.5 and 8 h. At all times up to 24 h, mean DR/R ratios for vitamin A-depleted rats (45 ± 6 nmoles of vitamin A/g liver) were approximately twice those for vitamin A-sufficient rats (230 ± 40 nmoles of vitamin A/g liver). In three well-nourished adults, presumably with liver reserves of > 300 nmol/g wet weight liver (> 80 μg retinol equivalents/g), and in two young (1- and 3-years old) well-nourished children, maximal DR/R ratios were < 0.023). In these cases, peak DR/R ratios were observed, with one possible exception, between 8 and 12 h. Thus, the MRDR assay, which is a useful indicator of marginal vitamin A status in rats, seems also applicable to humans.

Original languageEnglish (US)
Pages (from-to)219-224
Number of pages6
JournalEuropean Journal of Clinical Nutrition
Volume44
Issue number3
StatePublished - 1990
Externally publishedYes

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

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