TSH Levels and Hypothyroidism
Quote:
>I have several questions about Thyroid stimulating hormone (TSH).
>What level of TSH represents the boundary between a euthyroid condition and a
>hypothyroid one ?
>How much does a person's TSH level typically fluctuate, and what factors cause
>upwards or downwards fluctuations ?
>If someone has a TSH level near this borderline, should they take synthetic
>thyroid hormone ? What benefits does it have ?
>Rose Marie
TSH is felt to be the most sensitive indicator of hypothyroidism, but
it is a measurement that takes a fair amount of knowledge to interpret
correctly. There are some situations in which the TSH may be low, and
the person still hypothyroid --the best example being someone with
pituitary disease, who might be unable to generate TSH despite low
thyroxine levels. Also, after an acute illness, there may be mild
fluctuations in TSH level if the person went through a phase of being
"euthyroid sick" with a low T-4 and normal TSH. Some folks have
resistance to thyrotropin, and may have high normal T-4 and slightly
elevated TSH, and other people might have transient elevations of TSH
but when tested a few months later, may return to normal. The mild,
persistent elevations in TSH were thought to represent incipient
hypothyroidism, and were treated in the recent past, but now, if the
patient is going to be reliable in followup appointments, we often
just follow the TSH for a clear trend over time. Interpretation of
TSH also should include an evaluation of the patients symptoms and
medications. I've treated patients with compatible symptoms and only
mild elevations in TSH, and I've also treated patients with goitres
even if their TSH was normal (as is often the case in Hashimoto's
thyroiditis). H2
