Rosh Emergency Medicine Practice Test

What typical lab finding might confirm a diagnosis of hypothyroidism in a patient presenting with fatigue and weight gain?

1. Low free T4 level

2. High hemoglobin level

3. Normal vitamin B12 level

4. Increased liver enzymes

The correct answer is: Low free T4 level

A typical lab finding that would confirm a diagnosis of hypothyroidism in a patient presenting with symptoms such as fatigue and weight gain is a low free T4 level. In hypothyroidism, the thyroid gland does not produce enough thyroid hormones, which include thyroxine (T4) and triiodothyronine (T3). When the free T4 level is low, it indicates that the thyroid is underactive and not producing sufficient hormone levels to meet the body's metabolic needs. Other typical laboratory findings in hypothyroidism might also include elevated thyroid-stimulating hormone (TSH) levels due to the pituitary gland's effort to stimulate the underactive thyroid. This combination of low free T4 and high TSH confirms the diagnosis of hypothyroidism. The remaining options do not directly correlate with the diagnosis of hypothyroidism. A high hemoglobin level, although it may appear in some conditions, is not specific to thyroid function and could indicate other hematological issues. A normal vitamin B12 level does not relate to thyroid function or confirm hypothyroidism, as vitamin B12 status is independent of thyroid hormone levels. Lastly, increased liver enzymes are not a hallmark of hypothyroidism and could indicate a variety of other conditions such