Which of the following thyroid profiles is most compatible with a diagnosis of primary hypothyroidism?
- a low TSH (thyroid stimulating hormone) level and a high T4
- a low TSH level and a normal T4
- a low TSH level and a low T4
- a high TSH level and a low T4
- a high TSH and a high T4
High TSH level and a low T4
Low T4 is diagnostic for low thyroid function. If the pituitary is normal (as in primary thyroid disease) the TSH should be high as the pituitary tries to stimulate the failing thyroid gland.