Reassessment of Measuring Total Iron Binding Capacity in Acute Iron Overdose

Abstract

To evaluate recent data that suggest that total iron binding capacity (TIBC) is not a reliable laboratory parameter in assessing acute iron overdose. A MEDLINE search of the literature with a fan search of relevant articles. Laboratory, human, and animal studies on the measurement and relevance of TIBC in acute iron poisoning were reviewed. These data were analyzed in light of the current guidelines for use of TIBC in assessing iron poisoning. There are significant data to suggest that the sensitivity of TIBC in acute iron poisoning is unacceptable. This lack of sensitivity is also reflected in the poor positive predictive value of TIBC. The specificity and negative predictive value are higher but not without error. One survey of 500 laboratories reported a coefficient of variation for TIBC of 16 percent (95 percent confidence interval), suggesting unacceptable accuracy. These data suggest that TIBC may not be a reliable laboratory parameter in assessing acute iron poisoning. Studies are needed to develop a reliable analytical procedure for TIBC and to correlate TIBC with clinical outcomes in acute iron poisonings.