Unexplained fatigue in women: start iron supplements

By Sarah Guy

Iron deficiency may be underdiagnosed in women of child-bearing age who report considerable fatigue, say researchers whose randomized controlled trial results show a significant reduction in fatigue after women took iron supplements.

Specifically, the team reports an almost 50% fall in mean scores on the Current and Past Psychological Scale (CPPS) for fatigue in women assigned to iron supplementation for 12 weeks, compared with a 29% drop in their counterparts given a placebo - a significant difference.

None of the women were anemic at study baseline: all had hemoglobin levels of at least 12.0 g/dL although they had borderline low ferritin levels (under 50 µg/L), remark the researchers.

"If fatigue is not due to secondary causes, the identification of iron deficiency as a potential cause may prevent inappropriate attribution of symptoms to putative emotional causes or life stressors, thereby reducing the unnecessary use of health care resources, including inappropriate pharmacologic treatments," suggest Bernard Favrat (University of Lausanne, Switzerland) and colleagues.

They randomly assigned 198 women between the ages of 18 and 50 years who reported fatigue levels of at least 6 on a Likert scale of 1-10, and had no known pathology that could explain the fatigue, to either 80 mg/d oral prolonged-release ferrous sulfate (n=102), or placebo (n=96) for 12 weeks.

CPPS and global fatigue index scores (as measured by the multidimensional assessment of fatigue scale) improved by a significant 3.5 and 4.0 points in women treated with iron supplements compared with their peers who received placebo.

However, the women's' anxiety and depression scores - other quality of life indicators not directly related to fatigue - were unaffected by treatment assignment, write Favrat et al in the Canadian Medical Association Journal.

The team notes that the effects of iron deficiency on fatigue can be explained by decreased activity of iron-dependent enzymes; for example, those affecting the metabolism of neurotransmitters that enhance neurophysiologic changes.

And the known positive effects of iron including improved aerobic adaptation, endurance capacity, muscle fatigability, memory, and cognitive function, can explain the positive effects of iron supplements on physical and psychologic ferritin performance.

"For women with unexplained prolonged fatigue, iron deficiency should be considered," conclude the authors.

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