ETIOLOGIC DIAGNOSIS OF PRIMARY ADRENAL INSUFFICIENCY USING AN ORIGINAL FLOWCHART OF IMMUNE AND BIOCHEMICAL MARKERS

Approximately 70-80% of cases of primary adrenal insufficiency are cla ssified as idiopathic. An effective protocol for the etiological diagn osis of primary adrenal insufficiency is needed to ensure correct pati ent management. With the aim of developing an algorithm for the etiolo gical diagnosis of primary adrenal insufficiency, we studied 56 Italia n patients with nonsurgical primary adrenal insufficiency and 24 Frenc h patients with X-Linked adrenoleukodystrophy (ALD) for serum levels o f adrenal cortex, steroid-21-hydroxylase (210HAb), islet cell (ICA), g lutamate decarboxylase (GAD65Ab), IA2/ICA512 (ICA512Ab), thyroid perox idase (TPOAb) autoantibodies, and plasmatic concentrations of very lon g chain fatty acids (VLCFA). High levels of 21OH and adrenal cortex an tibodies were found in 35/42 (83%) and 17/42 (40%) Italian patients wi th idiopathic adrenal insufficiency, respectively. Levels of adrenal a utoantibodies correlated inversely with disease duration (P < 0.0001). Elevated VLCFA were found in 4/42 (10%) idiopathic patients. A total of 34/35 (97%) idiopathic patients with a disease duration of less tha n 20 yr was positive for either 21OHAb or elevated levels of VLCFA. No ne of 14 patients with posttuberculosis adrenal insufficiency had elev ated levels of either adrenal antibodies or VLCFA. ICA, GAD65Ab, ICA51 2Ab, and TPOAb were found in 6/56 (11%), 8/56 (14%), 4/56 (7%), and 23 /56 (41%) patients, respectively. None of 24 French ALD patients with adrenal insufficiency was positive for organ-specific autoantibodies. The measuring of 21OH antibodies and plasma VLCFA levels enabled a cor rect diagnosis of autoimmune (89%) and ALD (8%) in 97% of patients wit h idiopathic primary adrenal insufficiency of less than 20 yr of durat ion. The results of our study have important therapeutic and prognosti c implications.