A 31-year-old man comes to the physician because of a 9-month history of increasing fatigue and recurrent nausea. During this period, he has had a 3.8-kg (8.4-lb) weight loss. He also reports feeling lightheaded when he stands up suddenly. The patient has type 1 diabetes mellitus and has noticed decreased insulin requirements over this time. Physical examination shows hyperpigmentation of the lips and oral mucosa. Measurement of serum cortisol before and after administration of exogenous adrenocorticotropic hormone (ACTH) shows no difference in the levels. Which of the following changes in serum laboratory values is most likely present in this patient?

Question

A 31-year-old man comes to the physician because of a 9-month history of increasing fatigue and recurrent nausea. During this period, he has had a 3.8-kg (8.4-lb) weight loss. He also reports feeling lightheaded when he stands up suddenly. The patient has type 1 diabetes mellitus and has noticed decreased insulin requirements over this time. Physical examination shows hyperpigmentation of the lips and oral mucosa. Measurement of serum cortisol before and after administration of exogenous adrenocorticotropic hormone (ACTH) shows no difference in the levels.  Which of the following changes in serum laboratory values is most likely present in this patient?

Quizplus · Accepted Answer

Eductional Objective: Patients with type 1 diabetes mellitus are at increased risk for other autoimmune endocrinopathies, including primary adrenal insufficiency (Addison disease).  Electrolyte abnormalities in primary adrenal insufficiency include hyponatremia, hyperkalemia, hyperchloremia, and nonanion gap metabolic acidosis.

A 31-Year-Old Man Comes to the Physician Because of a 9-Month