Adult idiopathic isolated ACTH deficiency: a short series and literature review.

OBJECTIVES: Adult idiopathic isolated ACTH deficiency (AIIAD) is an underestimated disorder which is frequently misdiagnosed. We presented 3 new Chinese AIIAD cases, summarized their clinical characteristics and analyzed the available literature.

METHODS: Three cases of AIIAD managed in Chinese PLA General Hospital during the period 1998-2003 were retrospectively identified. We have collected information on clinical presentation, laboratory findings and treatment response. The clinical characteristics were summarized and pertinent literatures were analyzed.

RESULTS: Our 3 cases with AIIAD aged 52-68 years old were misdiagnosed for a long period of time. Clinical features of AIIAD were summarized by reviewing the limited literature: 1. Most patients were over 40 years; 2. Clinical presentations were insidious; 3. Usually no pigmentation; 4. Hypogonadism and amenorrhea could present; 5. mild hypoglycemia, hyponatremia, normal-high potassium, mild anemia, lymphocytosis and eosinophilia could present; 6. With low or absent cortisol, normal secretion of pituitary hormones other than ACTH; 7. High prevalence of thyroid disorder; 8. Usually present concomitantly with other autoimmune disease, which usually disappeared on steroid replacement; 9. Absence of structural pituitary defects except for empty sella; 10. No evidence in any infiltration, trauma, surgery, infectious or radiotherapy, or glucocorticoid medication; 11. No growth abnormalities.

CONCLUSION: AIIAD is an unspecified and underestimated condition with much misdiagnosis. We summarized the clinical features to improve the recognition. Indeed, every patient with unexplained hyponatremia and malaise, particularly in patients with autoimmune diseases, needs to be evaluated for the possibility of AIIAD.