A 30-year-old female complains of palpitations, fatigue, and insomnia. On physical exam, her extremities are warm and she is tachycardic. There is diffuse thyroid gland enlargement and proptosis. There is a thickening of the skin in the pretibial area. Which of the following lab values would you expect in this patient?

**Core Concept**
The patient's symptoms and physical exam findings are suggestive of hyperthyroidism, a condition characterized by an overproduction of thyroid hormones. The diffuse thyroid gland enlargement and proptosis are classic signs of Graves' disease, an autoimmune cause of hyperthyroidism.

**Why the Correct Answer is Right**
The patient's symptoms and lab values are consistent with Graves' disease, which is characterized by elevated levels of free thyroxine (FT4) and free triiodothyronine (FT3). The warm extremities and tachycardia are due to the increased metabolic rate caused by excess thyroid hormones. The skin thickening in the pretibial area is a characteristic feature of pretibial myxedema, a complication of Graves' disease.

**Why Each Wrong Option is Incorrect**
**Option A:** TSH (Thyroid-Stimulating Hormone) is typically low in primary hyperthyroidism, but the question stem does not provide enough information to confirm this as the correct answer.
**Option B:** Although thyroid-binding globulin (TBG) levels may be elevated in Graves' disease, this is not the most specific or sensitive marker for this condition.
**Option C:** Thyroid-stimulating immunoglobulins (TSI) are a hallmark of Graves' disease, but measuring TSI is not a routine part of the diagnostic workup.

**Clinical Pearl / High-Yield Fact**
Graves' disease is an autoimmune condition that affects about 1 in 100 people worldwide, making it the most common cause of hyperthyroidism. It is more common in women, especially between the ages of 20 and 40.

**Correct Answer:** D. Elevated FT4 and FT3.

✓ Correct Answer: B. Decreased TSH, increased total thyroxine