Which lab pattern describes secondary hyperthyroidism (all values elevated)?

• A. TSH high; FT4 high; TT3/TT4 high; T3 uptake high
• B. TSH low; FT4 high; TT3/TT4 high; T3 uptake high
• C. TSH high; FT4 low; TT3/TT4 low; T3 uptake low
• D. TSH normal; FT4 normal; TT3/TT4 normal; T3 uptake normal

Answer: (A)

In secondary hyperthyroidism, the pituitary continues to secrete TSH even when thyroid hormone levels are already high. That inappropriately high TSH drives the thyroid to produce more T4 and T3, so all thyroid-related measurements rise together. So seeing high TSH along with high free T4 and high total T3/T4 matches this pattern. The T3 uptake tends to be elevated as part of the hyperthyroid state as well, reinforcing the overall excess thyroid activity. This is distinct from primary hyperthyroidism, where the hormone excess suppresses TSH, and from hypothalamic/pituitary failure, where TSH would be low or inappropriately normal despite low or normal thyroid hormones.