what does primary thyroid disease affect?
the thyroid itself
what causes secondary thyroid disease?
hypothalamic or pituitary disease
diagnosis of primary hypothyroidism
free T3/4 low
TSH high
diagnosis of primary hyperthyroidism
free T3/4 high
TSH low
diagnosis of secondary hypothyroidism
free T3/4 low
TSH low/ normal
secondary hyperthyroidism
free T3/4 high
TSH high/normal
what is sub-clinical thyroid disease?
low or high TSH with a normal T3/4 which risks progression to overt
when should you avoid checking TFTs?
unwell patients as TSH is initially suppressed but then rises in recovery
known as non-thyroidal illness/ sick euthyroid syndrome