Adrenal insufficiency, be aware of drug interactions!

Abstract

Summary: A 42-year-old man with complaints of muscle soreness and an increased pigmentation of the skin was referred because of a suspicion of adrenal insufficiency. His adrenocorticotropic hormone and cortisol levels indicated a primary adrenal insufficiency (PAI) and treatment with hydrocortisone and fludrocortisone was initiated. An etiological workup, including an assessment for anti-adrenal antibodies, very long-chain fatty acids, 17-OH progesterone levels and catecholamine secretion, showed no abnormalities. 18Fluorodeoxyglucose positron emission tomography/CT showed bilateral enlargement of the adrenal glands and bilateral presence of an adrenal nodule, with 18fluorodeoxyglucose accumulation. A positive tuberculin test and positive family history of tuberculosis were found, and tuberculostatic drugs were initiated. During the treatment with the tuberculostatic drugs the patient again developed complaints of adrenal insufficiency, due to insufficient dosage of hydrocortisone because of increased metabolism of hydrocortisone.

Learning points: Shrinkage of the adrenal nodules following tuberculostatic treatment supports adrenal tuberculosis being the common aetiology. The tuberculostatic drug rifampicin is a CYP3A4 inducer, increasing the metabolism of hydrocortisone. Increase the hydrocortisone dosage upon initiation of rifampicin in case of (adrenal) tuberculosis. A notification on the Addison's emergency pass could be considered to heighten physician's and patients awareness of hydrocortisone drug interactions.

Keywords: 2019; ACTH; Adrenal; Adrenal insufficiency; Adult; Belgium; CT scan; CYP 3A4 inducers*; Corticotropin-releasing hormone stimulation test; Cortisol; DHEA Sulphate; Error in diagnosis/pitfalls and caveats; Fludrocortisone; General practice; Glucocorticoids; Hydrocortisone; Hyperpigmentation; Hypotension; Male; Mantoux test; Mineralocorticoids; Myalgia; Myambutol*; Nicotibine*; October; PET scan; Pyridoxine*; Renin (blood); Rifampicin*; Tebrazid*; Tuberculosis; Tuberculostatic drugs*; Tuberculous adrenalitis*; White.

Figure 1

Hyperpigmentation of skin and mucosae.

Figure 2

CT scan of the adrenals. Axial slices at diagnosis (panel A): right adrenal measuring 30 × 17 mm, left adrenal measuring 13 × 8 mm. A control scan 10 months after initiation of tuberculostatic drugs showed a shrinkage of the nodular adrenals (right adrenal: 26 × 14 mm, left adrenal: 7 × 5 mm, panel B).