Question: What should I ask my endocrinologist at my 3 months follow up? (my thyroid labs are all good except TSH).
Answer: While TSH is one of the Thyroid markers we have to look at, it is not an accurate marker without having a context of other thyroid labs.
Concerning TSH alone, we've already touched upon it in other article:
NORMAL TSH BUT STILL SYMPTOMATIC?
Today, however, we'd like to answer the question: "What to do if my thyroid labs are all good except TSH?".
Well, there can be various causes for this. Whether it's hypo or hyperthyroidism, low TSH is usually caused by one of the following:
Taking too much medication
Euthyroid Sick Syndrome
When it comes to taking too much thyroid medication, for Graves' disease, it can lead to the low serum concentration of TSH, with normal free T3 and T4 concentrations.
You can read more about it in this article: https://www.ncbi.nlm.nih.gov/pubmed/16807224
In this scenario, You should ask Your doctor: "Is my dose of the medication correct?".
The doctor should be able to asses You based on Your symptoms. Keep in mind that symptoms of exogenous hyperthyroidism (caused by taking too much medication) differ from the endogenous one (Graves' disease).
What will be the symptoms of taking too much medication?
Frequent bowel movements or diarrhoea.
Now, it's very IMPORTANT to note that these symptoms are MILDER than these from endogenous hyperthyroidism.
But what about hypothyroidism, can it also happen?
Yes, it can also happen in hypothyroidism.
Taking too high dose of medications like levothyroxine, Synthroid, Armour Thyroid, Cytomel etc. can influence Your TSH level and lower it down.
Typical symptoms of this will be hypothyroid symptoms like heart palpitations, losing Your hair, anxiety, hot flashes etc.
Another, very common reason for Low TSH with other labs being in range, is Pituitary dysfunction.
Pituitary dysfunction will present with symptoms like
Symptoms associated with a low TSH due to pituitary dysfunction include: