Within-person variance in biochemical indicators of iron status: Effects on prevalence estimates

Anne C. Looker, Christopher T. Sempos, Kiang Liu, Clifford L. Johnson, Elaine W. Gunter

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


The effect of within-person variance on prevalence estimates from population distributions based on a single measurement was examined for hematologic and iron-status indicators collected in the Hispanic Health and Nutrition Examination Survey (HHANES). Within-person to between person variance ratios (W:Bs) were estimated for 11 indicators by using data from 80 persons who provided blood twice in HHANES. Distributions of selected iron-status indicators from 20-44-y-old Mexican American females from HHANES were adjusted for within-person variance by using the W:B estimates, and prevalences of low values based on the original and adjusted distributions were compared. W:B were <1 for the majority of the indicators. Nonetheless, prevalences of low values from the original distributions were inflated when commonly used cutoff values were applied. Within-person variance in serum analytes needs to be controlled when the prevalence of a condition in populations is assessed.

Original languageEnglish (US)
Pages (from-to)541-547
Number of pages7
JournalAmerican Journal of Clinical Nutrition
Issue number3
StatePublished - 1990


  • intraindividual variation
  • iron status
  • nutrition surveys
  • within-person variation

ASJC Scopus subject areas

  • Nutrition and Dietetics
  • Medicine (miscellaneous)


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