FER ET FATIGUE

FER ET FATIGUE
QUESTION : La prise d’un supplément de fer peut-elle améliorer l’état de fatigue
chez un patient non anémique?
AUTEUR : Nina Paradis-Robert (DÉCEMBRE 2007)
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femmes en âge de procréer, fatiguées, sans cause psychiatrique ou
métabolique identifiée.
supplément de fer
aucune intervention (placebo)
amélioration de la fatigue
CONTEXTE : Une jeune femme me consulte en début de stage à Wakefield pour
fatigue. Il n’y a pas de cause identifiable à l’histoire ou à l’examen; j’anticipe un
bilan complètement normal. Cette patiente pourrait-elle être aidée par un
supplément de fer malgré l’absence d’anémie? Un hématologue aurait déjà dit
que c’était possible puisque certaines fonctions cellulaires semblent dépendre du
fer, indépendamment de l’hémoglobine.
RECHERCHE :
En utilisant différentes combinaisons de mots : Iron, ferrous, traitement,
supplementation, fatigue, tiredness, non-anemic.
Cochrane : Aucune revue sur le sujet
Avec différents moteurs de recherche : Pub med, Trip Database, Clinical
evidence : Un article correspond presque exactement à la question :
RÉSULTATS :
1) F Verdon, B Burnand, C-L Fallab Stubi, C Bonard, M Graff, A Michaud, T
Bischoff, M de Vevey, J-P Studer, L Herzig, C Chapuis, J Tissot, A Pécoud, B
Favrat. Iron supplementation for unexplained fatigue in non-anaemic
women: double blind randomised placebo controlled trial. BMJ 2003 May
24; 326 (7399): 1124
Objective: To determine the subjective response to iron therapy in non-anaemic
women with unexplained fatigue.
Design: Double blind randomised placebo controlled trial.
Setting: Academic primary care centre and eight general practices in western
Switzerland.
Participants: 144 women aged 18 to 55, assigned to either oral ferrous sulphate
(80 mg/day of elemental iron daily; n=75) or placebo (n=69) for four weeks.
Main outcome measures: Level of fatigue, measured by a 10 point visual
analogue scale.
Results: 136 (94%) women completed the study. Most had a low serum ferritin
concentration; <20 mg/l in 69 (51%) women. Mean age, haemoglobin
concentration, serum ferritin concentration, level of fatigue, depression, and
anxiety were similar in both groups at baseline. Both groups were also similar for
compliance and dropout rates. 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, 95% confidence interval 0.32 to
1.62; P=0.004). Subgroups analysis showed that only women with ferritin
concentrations <50 mg/l improved with oral supplementation.
Conclusion: Non-anaemic women with unexplained fatigue may benefit from iron
supplementation. The effect may be restricted to women with low or borderline
serum ferritin concentrations.
Commentaires dans : ACP Journal Club. 2004 Mar-Apr;140(2):43.
The small randomized controlled trial by Verdon and colleagues raises several
questions.
First, are the results biologically plausible? Iron is an important component in a
number of proteins involved in oxidative processes and muscle functioning, and a
recent review of animal and human research found some evidence that iron
deficiency without anemia may lead to decreased physical functioning .
Maximum oxygen consumption (VO2max) is decreased in nonanemic women with
low iron stores and improves with 6 weeks of iron supplementation.
Are the results clinically meaningful? The authors did not report improvement
rates, so numbers needed to treat cannot be calculated. The reported 0.97-point
decrease on a 10-point VAS is less than the 1.1 to 1.3 points found to represent
the minimal clinically appreciable difference when a VAS was used to measure
disability or pain.
How long should the treatment continue? Would more than 1 month of therapy
lead to more impressive results?
Is there a target ferritin level? The authors' subgroup analysis is somewhat
questionable, since only 21 women in their sample had ferritin levels > 50 µg/L.
Lorne A. Becker, MD
SUNY Upstate Medical University
Syracuse, New York, USA
2) Un autre article, sans être une étude, suggère que les suppléments de fer
pourraient améliorer la performance d’athlète même en l’absence d’anémie :
Rodenberg RE, Gustafson S. Iron as an ergogenic aid: ironclad evidence?
Curr sport Med Rep 2002 jul;6(4):258-64.
Iron supplementation for the iron-depleted nonanemic athlete is a controversial
issue. Athletes may be iron deficient due to poor dietary intake, significant or
obligatory blood loss, or deficiency via increased need secondary to intense
physical activity. Athletes who are found to be anemic secondary to iron
deficiency do benefit and show improved performance with appropriate iron
supplementation. There is contradictory evidence for iron supplementation and
improving performance in the iron-depleted nonanemic athlete. An athlete's iron
status is usually monitored via serum ferritin. Currently, there is no standardized
ferritin level at which supplementation is recommended, nor is there a consensus
as to the appropriate maintenance of ferritin. Screening endurance athletes or
female athletes in general for iron deficiency and also educating these athletes
regarding the importance of a balanced diet to maximize performance would
seem prudent and beneficial. Based on the literature, supplementation for the
iron-depleted nonanemic athlete does not appear to be justified to solely improve
performance.
CONCLUSION :
Je n’ai trouvé qu’une seule étude sur le sujet désiré. Je dois donc baser mes
conclusions sur cette seule étude qui, quoique qu’intéressante, ne comporte que
144 patientes. À la lumière de ces données, je crois que le traitement par
supplément de fer peut être considéré chez les femmes non-anémiques,
fatiguées et qui ont une ferritine «basse», étant donnés les faibles coûts et
risques associés aux suppléments de fer. Ceci dit, d’autres études devraient être
faites pour déterminer à partir de quelles valeurs de laboratoire un traitement
devrait être envisagé et à quelle dose.
Toutefois, bien que l’étude trouvée ait démontré une amélioration
statistiquement significative de la fatigue, je remets en doute la signification
clinique d’une telle amélioration (amélioration de 1 sur une échelle de 10).
Pourquoi les femmes seraient-elles les seules à bénéficier de ce traitement s’il
est efficace. Qu’en est-il pour les hommes?