Fatigue: a practical approach to diagnosis in primary care

Cornuz and colleagues [1], in the Box 2 of their article, provided a list of 11 initial laboratory tests for patients with prolonged or chronic fatigue. Considering that hypocortisolism is one of the most frequently reported abnormalities of patients with chronic fatigue syndrome (CFS) [2- 5], it is surprising that none of the available tests for assessing cortisol production [2-5] was included in that list. The importance of this assessment is especially evident in the light of the virtual recovery of CFS patients treated with low-dose hydrocortisone [6]. The great efficacy of this replacement therapy shows that hypocortisolism plays a central role in CFS.

The rationale for assessing cortisol production in patients with chronic fatigue is also based on the fact that CFS shares 43 clinical features with Addison’s disease [7,8], including hypocortisolism, chronic fatigue, and all the symptoms listed in the diagnostic criteria for CFS [7]. This impressive clinical overlap, which constitutes a similarity between two distinctly named diseases that is probably unequalled in the medical literature, suggests that CFS should practically be regarded as a mild form of Addison’s disease [7].

Although Cornuz et al [1], in the Table 1 of their paper, correctly included Addison’s disease in the list of the major underlying causes of fatigue, they should have remarked that “pigmentation in skin creases, scars and buccal mucosa” [1] is far from being a constant feature of Addison’s disease [9,10]. Therefore, the absence of this pigmentation in patients with chronic fatigue should not mislead general practitioners to exclude hypocortisolism as a possible cause of that unremitting symptom.

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References

1. Cornuz J, Guessous I, Favrat B. Fatigue: a practical approach to diagnosis in primary care. CMAJ 2006;174(6):765-7.

2. Jerjes WK, Peters TJ, Taylor NF, Wood PJ, Wessely S, Cleare AJ. Diurnal excretion of urinary cortisol, cortisone, and cortisol metabolites in chronic fatigue syndrome. J Psychosom Res 2006;60:145-53.

3. Roberts AD, Wessely S, Chalder T, Papadopoulos A, Cleare AJ. Salivary cortisol response to awakening in chronic fatigue syndrome. Br J Psychiatry 2004;184:136-41.

4. Cleare AJ, Blair D, Chambers S, Wessely S. Urinary free cortisol in chronic fatigue syndrome. Am J Psychiatry 2001;158:641-3.

5. Scott LV, Medbak S, Dinan TG. Blunted adrenocorticotropin and cortisol responses to corticotropin-releasing hormone stimulation in chronic fatigue syndrome. Acta Psychiatr Scand 1998;97:450-7.

6. Cleare AJ, Heap E, Malhi GS, Wessely S, O'Keane V, Miell J. Low- dose hydrocortisone in chronic fatigue syndrome: a randomised crossover trial. Lancet 1999;353:455-8.

7. Baschetti R. Chronic fatigue syndrome: an endocrine disease off limits for endocrinologists? Eur J Clin Invest 2003;33:1029-31.

8. Baschetti R. Chronic fatigue syndrome, pregnancy, and Addison disease [letter]. Arch Intern Med 2004;164:2065.

9. Kendereski A, Micic D, Sumarac M, Zoric S, Macut D, Colic M, et al. White Addison's disease: what is the possible cause? J Endocrinol Invest 1999;22:395-400.

10. Soule S. Addison's disease in Africa--a teaching hospital experience. Clin Endocrinol 1999;50:115-20.

Conflict of Interest:

None declared