MKSAP Quiz: Hypothyroidism
A 70-year-old woman with hypothyroidism fell and fractured her hip. During preoperative evaluation for hip fracture repair, she mentions recent mild fatigue, which has not significantly limited performance of her daily activities, and ongoing right upper-quadrant abdominal pain after eating. She takes levothyroxine, 0.075 mg daily.
Physical examination is normal except for moderate obesity.
Laboratory results show mild anemia (hemoglobin 11 g/dL [6.83 mmol/L] and hematocrit 34% [0.34]). Serum thyroid-stimulating hormone level is 11.2 µU/mL (11.2 mU/L), thyroxine level is 7.2 µg/dL (92.67 nmol/L), and triiodothyronine uptake is 45% (0.45). Liver chemistry tests are normal.
Which of the following management options is most appropriate?
A. Proceed with surgery
B. Increase levothyroxine dosage and delay surgery until thyroid levels are normal
C. Administer intravenous thyroid hormone and proceed with surgery
D. Administer intravenous thyroid hormone plus hydrocortisone and proceed with surgery
Answer and Critique
The correct answer is A) Proceed with surgery. This question can be found in MKSAP 14 in the General Internal Medicine section, Item 34.
This patient has mild, or subclinical, hypothyroidism. Patients with mild or moderate hypothyroidism can safely undergo surgery. Because levothyroxine's half-life is 5 to 9 days, mildly hypothyroid and euthyroid patients who are fasting can go without replacement therapy for several days. For patients with severe hypothyroidism, elective surgery should be delayed until thyroid hormone is partly or fully replaced. Severely hypothyroid patients who need urgent or emergent surgery should have an endocrinologic consultation and intravenous levothyroxine, triiodothyronine, and corticosteroids as needed for possible adrenal insufficiency.
Patients with mild hyperthyroidism need not delay elective surgery. In moderate or severe hyperthyroidism, elective surgery should be delayed and ß-blockers should be administered until a normal thyroid level is achieved. Patients with moderate or severe disease who need urgent or emergent surgery should have an endocrinologic consultation and ß-blockers, thyroid antagonists (for example propylthiouracil), and corticosteroids as needed for possible hypoadrenalism.
Key Point
- Patients with mild or moderate hypothyroidism can safely have surgery.
