Overactive thyroid

Clinically: Hyperthyroidism · also overactive thyroid, thyrotoxicosis, Graves disease

endocrine ICD-10 E05.90 MONDO MONDO:0004425 unverified

This describes what this condition typically looks like. It is not a diagnosis and cannot tell you whether you have it -- patterns overlap, results vary between labs, and the same numbers mean different things in different people. Diagnosis usually rests on Thyrotropin, Thyroxine, free, Triiodothyronine, free, interpreted alongside symptoms and history rather than read off a report.

unverified These explanations are written to be easy to read and have not yet been checked against a source. The ranges and measurement notes on this page show theirs.

definition unverified

Your thyroid is making too much hormone. Everything then runs faster than it should. That includes your heart rate, your digestion, and often your thoughts.

Production by the thyroid gland of more thyroid hormone than the body needs, most commonly due to Graves' disease, an autoimmune disorder that drives the gland to overproduce hormone; other causes include overactive nodules and thyroiditis. Excess hormone suppresses pituitary TSH release, so TSH is typically low, while T4 may be high.

caveats unverified

The signal runs backwards here too. A LOW TSH points to an OVERactive thyroid. Your brain has gone quiet because there is already plenty of hormone in your blood.

No clinical version written yet.

How common it is

Less common than an underactive thyroid, and again more frequent in women.

The typical lab pattern

What the diagnosis rests on

The results a diagnosis is actually made on.

Thyrotropin	low	—	Suppressed (low) in hyperthyroidism, and usually the first test checked. It can be undetectable even in mild cases.
Thyroxine, free	high	—	High in overt hyperthyroidism, together with a suppressed TSH. It can be normal in milder cases.
Triiodothyronine, free	high	—	High in overt hyperthyroidism. In milder cases free T3 may be the only raised hormone, so it is measured when T4 is normal.

Consistent with it

Fits the picture, but not enough on its own.

Alkaline phosphatase

high

—

Often raised in untreated hyperthyroidism, from faster bone turnover.

How it usually feels

Frequencies say how often a symptom accompanies this condition — not the other way round. Most people with any of these symptoms do not have this.