USMLE Step 2 CK Endocrine Emergencies Questions: DKA, Thyroid Storm and Adrenal Crisis

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Endocrine emergencies are classic USMLE Step 2 CK material because the order of treatment matters. Giving the right drug in the wrong order can harm the patient, and the exam tests exactly that. Try these three questions, then check the explanations.

Question 1: A young man with type 1 diabetes, vomiting and deep breathing

A 19-year-old man with type 1 diabetes has had vomiting and abdominal pain for 1 day. He has deep, rapid breathing. Pulse is 118/min and blood pressure is 102/64 mm Hg. Serum glucose is 520 mg/dL, potassium 5.6 mEq/L, bicarbonate 9 mEq/L, and arterial pH 7.12. Urine ketones are strongly positive. An intravenous infusion of 0.9% saline has been started. Which of the following is the most appropriate next step?

A. Intravenous sodium bicarbonate
B. Intravenous regular insulin infusion
C. Intravenous potassium chloride before any insulin
D. Subcutaneous long-acting insulin only
E. Intravenous phosphate replacement

Correct answer: B. Intravenous regular insulin infusion

This is diabetic ketoacidosis. Treatment is IV fluids, IV insulin, and careful potassium management. Always check potassium before insulin: insulin shifts potassium into cells. If K⁺ is below 3.3 mEq/L, hold insulin and replace potassium first. If K⁺ is 3.3–5.2, give insulin and add potassium to the fluids. Here K⁺ is 5.6, so start the insulin infusion and monitor potassium closely. Total body potassium is low despite the high serum level, so it will drop with treatment. Add dextrose when glucose falls to about 200–250 mg/dL, and continue insulin until the anion gap closes.

Why the other options are wrong:

  • Sodium bicarbonate is generally reserved for very severe acidosis (pH below about 6.9).
  • Potassium before insulin is needed only when K⁺ is below 3.3 mEq/L.
  • Subcutaneous long-acting insulin alone is not adequate for DKA. It is started before stopping the IV infusion, to prevent rebound ketoacidosis.
  • Phosphate is not routinely needed and is given only if levels are very low.

Question 2: Fever, atrial fibrillation and agitation in a patient with Graves disease

A 34-year-old woman with untreated Graves disease develops a urinary tract infection. She is now confused and agitated, with a temperature of 40.1°C (104.2°F), an irregular pulse of 150/min, vomiting and diarrhea. Intravenous propranolol has been started. Which of the following should be given at least 1 hour before potassium iodide?

A. Radioactive iodine
B. Levothyroxine
C. Propylthiouracil
D. Aspirin
E. Emergency total thyroidectomy

Correct answer: C. Propylthiouracil

This is thyroid storm, triggered by infection. Treatment includes a beta-blocker (propranolol), a thionamide (PTU or methimazole), iodine, glucocorticoids, and supportive care. The thionamide must be given at least 1 hour before iodine. Otherwise, the iodine can be used as raw material to make more thyroid hormone. PTU is often preferred in storm because it also blocks peripheral conversion of T4 to T3.

Why the other options are wrong:

  • Radioactive iodine is definitive therapy for Graves disease but is not used in acute storm.
  • Levothyroxine would make thyrotoxicosis worse.
  • Aspirin should be avoided because it displaces thyroid hormone from binding proteins; use acetaminophen for fever.
  • Thyroidectomy is done after the patient is stabilized and euthyroid, not as emergency treatment.

Question 3: Hypotension after surgery that does not respond to vasopressors

A 45-year-old man with rheumatoid arthritis has taken prednisone 20 mg daily for 3 years. His prednisone was stopped when he was admitted for an elective hip replacement. A few hours after surgery, he becomes hypotensive (blood pressure 78/40 mm Hg) despite 3 liters of IV fluids and a norepinephrine infusion. Serum sodium is 131 mEq/L and glucose is 62 mg/dL. Which of the following is the most appropriate next step?

A. Increase the norepinephrine dose and add vasopressin
B. Oral fludrocortisone alone
C. Perform a cosyntropin stimulation test before any treatment
D. Intravenous hydrocortisone
E. Broad-spectrum antibiotics only

Correct answer: D. Intravenous hydrocortisone

Long-term glucocorticoid use suppresses the hypothalamic-pituitary-adrenal axis. Stopping prednisone before the stress of surgery has caused acute adrenal crisis: shock that does not respond to fluids and vasopressors, with hyponatremia and hypoglycemia. Treatment is IV hydrocortisone immediately, along with fluids and dextrose. Do not delay treatment for testing. A cortisol level can be drawn before the first dose if it will not delay care.

Why the other options are wrong:

  • More vasopressors will not work without cortisol, which is needed for normal vascular response to catecholamines.
  • Fludrocortisone alone replaces mineralocorticoid only; aldosterone is usually preserved in steroid-induced (secondary) adrenal insufficiency.
  • Stimulation testing first dangerously delays life-saving therapy.
  • Antibiotics are reasonable if sepsis is suspected, but they do not treat adrenal crisis.

Key takeaways

  • DKA: fluids first, then insulin if K⁺ is at least 3.3; replace potassium as it falls.
  • Thyroid storm: beta-blocker, then PTU or methimazole at least 1 hour before iodine, plus steroids.
  • Shock unresponsive to pressors in a patient on chronic steroids = adrenal crisis: give IV hydrocortisone now.

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Written and reviewed by Dr. Ray Makar, MD, dermatologist with 20 years of clinical practice. Last reviewed: October 2026. For exam preparation only, not medical advice.

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