Mx of high TSH

diagnosis of hypothyroidism

persistently high TSH with low free T4 suggest primary hypothyroidism
- free T3 levels don't add much
persistently high TSH (usually to 5-10IU/L) with normal free T4 suggest subclinical primary hypothyroidism and typical symptoms may be absent.
low free T4 without elevated TSH levels suggest secondary hypothyroidism due to pituitary disorders
low free T3 without elevated TSH levels has been called Low T3 syndrome
- usually also have higher levels of a hormone known as reverse T3
- appears to be present in less than 20% of CFS and it might play a role in worsening conditions like kidney disease or serious infections
if cause is not obvious then:
- high titres of antithyroid antibodies (thyroid peroxidase, antimicrosomal, or antithyroglobulin) indicate an autoimmune cause