Iron Supplements May Help Fatigued Women
British Medical Journal (BMJ)

05/22/2003
By Harvey McConnell

Women who experience unexplained fatigue, but who are not anaemic may benefit from iron supplementation.

However, the effect of any iron supplementation may be restricted to women with low or borderline serum ferritin concentrations, reports Dr Bernard Favrat and colleagues at the University of Lausanne, Switzerland. They think their study is the first randomised clinical trial in women of childbearing age to show that iron supplementation could have an effect on fatigue in the absence of anaemia.

The clinicians point out that while the symptoms of fatigue are related to iron deficiency anaemia, there is a lack of evidence for any association between deficiency and tiredness in the absence of anaemia. Their double-blind randomised placebo controlled trial was among 144 women aged 18 to 55, referred from 8 family practices. Seventy- five women were assigned for 4 weeks to oral ferrous sulphate (80 mg/day of elemental iron daily), and 69 women to placebo.

Among the 136 women who completed the trial, most had a low serum ferritin concentration, and it was less than 20 µg/L in 69 (51%) of them. Mean age, haemoglobin concentration, serum ferritin concentration, level of fatigue, depression, and anxiety were similar in both groups at baseline, as well as compliance in the trial.

The level of fatigue after one month decreased by - 1.82/6.37 points (29%) in the iron group, compared with - 0.85/6.46 points (13%) in the placebo group (difference 0.95 points).

Subgroups analysis showed that only women with ferritin concentrations of less than 50 µg/l improved with oral supplementation. 'This suggests that iron deficiency could be present even with a 'normal' concentration of serum ferritin, Dr Favrat and colleagues said.

"Indeed, the lower limit for serum ferritin concentration is controversial: iron stores in the bone marrow may serve as a better indicator of iron deficiency, they add. The lower reference limits for serum ferritin and haemoglobin concentrations have been considered too low for women and it has been suggested should be the same as for men."
BMJ 2003;326: 1124-1126.