Fatigue and Skin Pigmentation

🗒️ Question

A 42 year old woman presents with fatigue, unintentional weight loss, generalised muscle weakness and occasional dizziness on standing. She has noticed increased pigmentation on her palms and gums. She reports reduced appetite and salt cravings.

On examination, her blood pressure is 90/60 mmHg, her pulse is 88 bpm and regular and there is evidence of hyperpigmentation on the buccal mucosa and palmar creases.

Investigations

• Serum sodium: 128 mmol/L (135–145)

• Serum potassium: 5.8 mmol/L (3.5–5.0)

• Random cortisol: 120 nmol/L (>450 nmol/L)

• ACTH: Elevated

What is the most likely diagnosis?

(A) Primary hypothyroidism

(B) Adrenal incidentaloma

(C) Chronic fatigue syndrome

(D) Addison's disease

(E) Phaeochromocytoma