Examkin

Question

Difficulty: Very hardGeneral Internal Medicine

Emergency medical services bring a 68-year-old male to the resuscitation bay due to progressive unresponsiveness and profound weakness over the last two days. According to his family, he recently recovered from a mild viral upper respiratory infection. His past medical history is significant for severe chronic obstructive pulmonary disease, ischemic cardiomyopathy with an ejection fraction of 35%, and a nonfunctioning pituitary macroadenoma for which he underwent transsphenoidal surgical resection six months ago. He was prescribed multiple replacement therapies postoperatively but abruptly discontinued all medications three weeks ago due to loss of insurance.

Vital signs show a temperature of 35.4 °C (95.7 °F), pulse of 46/min, blood pressure of 74/40 mm Hg, respirations of 24/min, and oxygen saturation of 89% on room air. Physical examination reveals a somnolent, difficult-to-arouse patient. Jugular venous distension is absent. Chest auscultation demonstrates distant breath sounds with prolonged expiration and faint diffuse wheezing, but no crackles. Cardiac examination shows a regular, bradycardic rhythm with muffled heart sounds. The extremities are cool with delayed capillary refill, and there is notable non-pitting periorbital and lower extremity edema.

Laboratory studies reveal:
TestResult
Sodium120 mEq/L
Potassium4.2 mEq/L
Chloride90 mEq/L
Bicarbonate14 mEq/L
Blood urea nitrogen48 mg/dL
Creatinine2.1 mg/dL
Glucose52 mg/dL
Thyroid-stimulating hormone (TSH)0.2 µU/mL (Normal: 0.4-4.0 µU/mL)
Free T40.3 ng/dL (Normal: 0.9-1.7 ng/dL)
An arterial blood gas on room air shows:
TestResult
pH7.28
PaCO230 mm Hg
PaO255 mm Hg

Electrocardiogram demonstrates sinus bradycardia with low-voltage QRS complexes.

Which of the following is the most appropriate initial step in the management of this patient?

  1. A
    Administration of loop diuretics and noninvasive positive pressure ventilation
  2. B
    Empiric therapy with a broad-spectrum beta-lactam/beta-lactamase inhibitor
  3. C
    Infusion of hypertonic sodium bicarbonate solution
  4. D
    Initiation of high-dose thyroid hormone replacement
  5. Immediate administration of stress-dose glucocorticoidsAnswer

Answer

Immediate administration of stress-dose glucocorticoids
The patient's presentation of severe hypotension, hypoglycemia, hyponatremia, hypothermia, and bradycardia following abrupt cessation of medications after a transsphenoidal resection is classic for panhypopituitarism, resulting in simultaneous adrenal crisis and myxedema coma. The most critical, life-saving intervention is the immediate administration of stress-dose glucocorticoids. Crucially, in any patient with suspected concomitant adrenal insufficiency and hypothyroidism, glucocorticoids MUST be given before thyroid hormone replacement. Giving thyroid hormone first increases the metabolic rate and cortisol clearance, which can precipitate a fatal adrenal crisis.

Step-by-Step Solution

1
Analyze the patient's history and vital signs.
The patient has a history of transsphenoidal pituitary resection and recently stopped all medications, placing him at high risk for panhypopituitarism. He presents in shock (blood pressure 74/40 mm Hg) with hypothermia and bradycardia.
Establishing the underlying vulnerability is crucial to identifying the specific etiology of the shock.
2
Interpret the laboratory and physical exam findings.
Labs show hypoglycemia, hyponatremia, and central hypothyroidism (low TSH, low free T4). The arterial blood gas shows a metabolic acidosis with appropriate respiratory compensation (PaCO2PaCO_2 of 30 mm Hg matches the Winter's formula calculation).
These findings confirm central adrenal insufficiency (causing hyponatremia, hypoglycemia, and shock) and central hypothyroidism (causing bradycardia, hypothermia, and non-pitting edema).
3
Determine the necessary sequence of pharmacological interventions.
Both adrenal crisis and myxedema coma require emergent treatment, but glucocorticoids must be administered before thyroid hormone.
Administering thyroid hormone increases the basal metabolic rate and hepatic clearance of cortisol. In a cortisol-deficient state, this will precipitate a potentially fatal adrenal crisis.

Key Concept

In patients with suspected panhypopituitarism presenting with combined adrenal crisis and myxedema coma, stress-dose glucocorticoids must be administered before thyroid hormone replacement to prevent precipitating a fatal adrenal crisis.
Rate this question

Topics

General Internal Medicine

More questions from this topic