In euthyroid sick syndrome, which of the following is true about thyroid hormone levels?

In euthyroid sick syndrome, which of the following is true about thyroid hormone levels?

• A. They are elevated
• B. They are reduced only in TSH suppressed
• C. They are normal
• D. They are reduced in clinically euthyroid patients with nonthyroidal illness

Answer: (D)

Euthyroid sick syndrome occurs when illness outside the thyroid itself alters thyroid hormone tests in someone with a normal thyroid. The body's response to systemic illness and cytokines changes how thyroid hormones are produced, converted, and cleared. The most common finding is a drop in the active hormone T3, and in more severe or prolonged illness T4 can also fall, while TSH may stay normal or be low. This means that clinically euthyroid patients with nonthyroidal illness can indeed have reduced thyroid hormone levels, even though their thyroid gland itself is functioning normally. That’s why this statement is the best fit.

Euthyroid sick syndrome occurs when illness outside the thyroid itself alters thyroid hormone tests in someone with a normal thyroid. The body's response to systemic illness and cytokines changes how thyroid hormones are produced, converted, and cleared. The most common finding is a drop in the active hormone T3, and in more severe or prolonged illness T4 can also fall, while TSH may stay normal or be low. This means that clinically euthyroid patients with nonthyroidal illness can indeed have reduced thyroid hormone levels, even though their thyroid gland itself is functioning normally. That’s why this statement is the best fit.