What is Cushing’s syndrome?

A 28-year-old lady presents with complaints of fatigue, inability to climb stairs, since the last two years. She is irritable and has bouts of crying and has stopped pursuing her job as a teacher and prefers to stay at home. She has been found to have hyperglycemia requiring treatment for the same time. Most of her complaints started about 2 years ago when she was put on herbal supplements to increase her appetite and body weight. On examination, she is conscious, appears lost in thought, has thin skin on the dorsum of her hand, purple-colored striae on her abdomen and calves measuring around 1 cm in width. She has patches of red bruises on her inner arms. Her waist circumference is 96 cm and blood pressure is 150/90 mm Hg. She has proximal myopathy of both upper and lower limbs. She has no hirsutism or increased pigmentation. A clinical diagnosis of Cushing’s syndrome is made. She is asked to stop her herbal supplements. An 8 am cortisol assay is done which reveals cortisol of <0.1 mg/dL. A diagnosis of exogenous Cushing’s syndrome is made.

What is Cushing’s syndrome?