A 62-year-old man is brought to the emergency department by his daughter due to progressiv… — USMLE Step 2 CK

A 62-year-old man is brought to the emergency department by his daughter due to progressive lethargy, confusion, and generalized swelling over the past week. He has a history of hypertension, chronic obstructive pulmonary disease (COPD), and a pituitary macroadenoma treated with transsphenoidal resection two years ago. His medications include amlodipine and a fluticasone-vilanterol inhaler. On arrival, he is difficult to arouse. Temperature is 35.1°C (95.2°F), pulse is 48/min, respirations are 10/min, and blood pressure is 95/60 mm Hg. Pulse oximetry shows 92% on room air. Physical examination reveals periorbital puffiness, non-pitting edema of the lower extremities, and delayed relaxation phase of deep tendon reflexes. Pulmonary auscultation reveals diminished breath sounds bilaterally but no crackles. Laboratory results are as follows:

Laboratory Test	Result
Sodium	128 mEq/L
Potassium	4.1 mEq/L
Chloride	96 mEq/L
Bicarbonate	24 mEq/L
Blood urea nitrogen	18 mg/dL
Creatinine	1.0 mg/dL
Glucose	58 mg/dL
Thyroid-stimulating hormone (TSH)	1.3 µU/mL (Normal: 0.5–5.0 µU/mL)
Free thyroxine (T4)	0.4 ng/dL (Normal: 0.9–1.7 ng/dL)

Arterial blood gas on room air:

Parameter	Result
pH	7.31
pCO2	52 mm Hg
pO2	65 mm Hg

Which of the following is the most appropriate next step in management?

Administer intravenous hydrocortisone followed by intravenous levothyroxineAnswer
B
Administer intravenous levothyroxine monotherapy immediately
C
Initiate intravenous furosemide and noninvasive positive pressure ventilation
D
Administer intravenous sodium bicarbonate
E
Initiate empiric piperacillin-tazobactam and vancomycin

Answer

Administer intravenous hydrocortisone followed by intravenous levothyroxine

The clinical presentation of severe hypothyroidism (hypothermia, bradycardia, delayed reflexes, altered mental status) alongside hypoglycemia, hyponatremia, and a history of pituitary resection strongly suggests panhypopituitarism presenting as myxedema coma with concurrent secondary adrenal insufficiency. The laboratory findings of a low free T4 with an inappropriately normal TSH confirm central hypothyroidism. In patients with panhypopituitarism, replacing thyroid hormone without first establishing adequate glucocorticoid coverage increases the basal metabolic rate and accelerates cortisol clearance, which can precipitate a fatal adrenal crisis. Therefore, intravenous hydrocortisone must be administered before or simultaneously with intravenous levothyroxine.

Step-by-Step Solution

Interpret the thyroid function tests and clinical signs.

A low free T4 with an inappropriately normal TSH in a patient with a history of pituitary resection indicates secondary (central) hypothyroidism.

Recognizing central hypothyroidism is critical because it implies potential involvement of other pituitary axes, most notably the adrenal axis.

Identify the acute clinical syndrome based on vital signs and labs.

Hypothermia, bradycardia, hypoglycemia, hyponatremia, and altered mental status confirm myxedema coma with highly suspected concurrent secondary adrenal insufficiency (panhypopituitarism).

The combination of severe hypothyroidism symptoms with hypoglycemia and hypotension points to a dual endocrine deficiency.

Determine the appropriate sequence of therapeutic interventions.

Glucocorticoids (hydrocortisone) must be administered before thyroid hormone replacement.

Levothyroxine increases the basal metabolic rate and accelerates the hepatic clearance of cortisol. Giving it without glucocorticoid coverage can precipitate a fatal adrenal crisis.

Key Concept

In patients with suspected panhypopituitarism presenting with myxedema coma, glucocorticoids must be administered prior to thyroid hormone replacement to avoid precipitating an acute adrenal crisis.

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics

More questions from this topic