A patient with TSH 60 mIU/L, FT4 5 pmol/L, FT3 3.0 pmol/L; which diagnosis is most likely?

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Multiple Choice

A patient with TSH 60 mIU/L, FT4 5 pmol/L, FT3 3.0 pmol/L; which diagnosis is most likely?

High TSH with a low free thyroxine (FT4) shows overt primary hypothyroidism, meaning the thyroid gland is not producing enough hormones despite pituitary signaling. In this case, a TSH of 60 mIU/L is markedly elevated and FT4 is only 5 pmol/L, with FT3 also on the low side, which fits hypothyroidism caused by loss of thyroid function. Graves disease would push FT4/FT3 up and suppress TSH, not raise it. Subclinical hypothyroidism would have an elevated TSH but a normal FT4, whereas this patient has low FT4. Sick euthyroid describes thyroid test abnormalities due to another illness, not this clear pattern of high TSH with low thyroid hormones. The combination best points to Hashimoto's disease, the autoimmune destruction of the thyroid that leads to reduced hormone production and compensatory TSH elevation.

High TSH with a low free thyroxine (FT4) shows overt primary hypothyroidism, meaning the thyroid gland is not producing enough hormones despite pituitary signaling. In this case, a TSH of 60 mIU/L is markedly elevated and FT4 is only 5 pmol/L, with FT3 also on the low side, which fits hypothyroidism caused by loss of thyroid function. Graves disease would push FT4/FT3 up and suppress TSH, not raise it. Subclinical hypothyroidism would have an elevated TSH but a normal FT4, whereas this patient has low FT4. Sick euthyroid describes thyroid test abnormalities due to another illness, not this clear pattern of high TSH with low thyroid hormones. The combination best points to Hashimoto's disease, the autoimmune destruction of the thyroid that leads to reduced hormone production and compensatory TSH elevation.

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