Iron deficiency, which has been linked with restless legs syndrome, can develop years before anemia and can be missed by hemoglobin testing alone, reports Penn State News.

In a second study, the researchers next looked at whether a specially developed questionnaire could better predict iron status. Questions were included on depression, poor attention and daytime sleepiness, symptoms which all have been associated with iron deficiency or iron deficiency anemia, but were not captured in the prior NHANES analyses. This questionnaire was compared to the currently recommended four iron deficiency anemia-risk questions in the Bright Futures Adolescent Previsit Questionnaire, a survey recommended for physician use by the American Academy of Pediatrics.