<prompt> A 63-year-old man recently treated for renal tuberculosis presents with weight loss, diarrhea, hypoglycemia, hypotension, and is noted to have hyperpigmented buccal mucosa, palmar and hand creases. Which investigation is most suitable for this clinical presentation?Serum iron and ferritinSerum copper and ceruloplasminPlasma ACTH and cortisolGene XPERT and Intravenous pyelography  <response>: Ans. C Plasma ACTH and cortisolRef: CMDT 2019 page 323 The key finding of hyperpigmentation of buccal mucosa, palmar and sole creases point to etiology of Addison disease. The leading cause of Addisons disease in India is tuberculosis. The presence of hypotension indicates hypoaldosteronism in Addisons disease. Simultaneous mention of hypoglycemia indicates cortisol deficiency. Choice B is done in case of hemochromatosis and bronze diabetes Choice C is done in case of Wilson disease Choice D is done in for diagnosis of tuberculosis 