Endocrine Abstracts

JOINT527

Phosphomannomutase 2 - Congenital Disorder of Glycosylation (PMM2-CDG) is a hereditary defect causing hypoglycosylation of N-linked glycoproteins and a multisystem disorder with a broad spectrum of clinical presentation. It was recently suggested that patients with PMM2-CDG may have central adrenal insufficiency. We present an 18-year-old male with PMM2-CDG, whose initial screening suggested adrenal insufficiency. The patient displayed a morning baseline plasma cortisol of 57 nmol/l, a deficient response to Adrenocorticotropic hormone (ACTH) with a 30 min cortisol of 165 nmol/l, and a low-normal ACTH. Analysis of cortisol binding globulin (CBG) showed abnormally low levels (253 mmol/l (ref. 750-2500 mmol/l)). 8 a.m. salivary cortisol was measured 24 hs after last hydrocortisone ingestion and was normal to slightly elevated (38 nmol/l (ref. 2.48-29 nmol/l)). Accordingly, the patient never experienced obvious symptoms of adrenal insufficiency nor clinical improvement after transient introduction of hydrocortisone. In conclusion, we present a patient with PMM2-CDG who upon measurement of plasma cortisol displayed “biochemical” central adrenal insufficiency, although with low CBG and normal salivary free cortisol levels. The case illustrates the caveats of using total plasma cortisol for the diagnosis of adrenal insufficiency in patients with PMM2-CDG and highlights the potential impact of N-linked hypoglycosylation on endocrine evaluation.