A 68-year-old woman has a TSH level of 8.7 uU/mL. This finding most strongly supports:

• A. Primary hypothyroidism
• B. Graves disease
• C. TSH-secreting tumor
• D. Primary hyperthyroidism

Answer: (A)

Elevated TSH signals that the pituitary is trying to stimulate the thyroid because thyroid hormone levels are likely low. This pattern points to a primary thyroid problem rather than a pituitary or central cause. In primary hypothyroidism, low thyroid hormone fails to provide negative feedback, so TSH rises. By contrast, Graves disease and other hyperthyroid states push thyroid hormone levels up and suppress TSH, and a TSH-secreting tumor would typically be associated with high TSH alongside high thyroid hormones. So this TSH elevation most strongly supports primary hypothyroidism. If available, a low free T4 would further confirm the diagnosis.