Symptoms
- Sudden weight loss, even when your appetite and the amount and type of food you eat remain the same or even increase
- Rapid heartbeat (tachycardia), irregular heartbeat (arrhythmia) or pounding of your heart (palpitations)
- Nervousness, anxiety and irritability
- Tremor — usually a fine trembling in your hands and fingers
- Sweating
- Changes in menstrual patterns
- Increased sensitivity to heat
- Changes in bowel patterns, especially more frequent bowel movements
- An enlarged thyroid gland (goiter), which may appear as a swelling at the base of your neck
- Fatigue, muscle weakness
- Difficulty sleeping
- Skin thinning
- Fine, brittle hair
Causes of hyperthyroidism
- Graves’ disease: Graves’ disease, an autoimmune disorder, is the most common cause of hyperthyroidism. It causes antibodies to stimulate the thyroid to secrete too much hormone. Graves’ disease occurs more often in women than in men. It tends to run in families, which suggests a genetic link.
- thyroiditis, or inflammation of the thyroid, which causes T4 and T3 to leak out of the gland
- tumors of the ovaries or testes
- benign tumors of the thyroid or pituitary gland
- large amounts of tetraiodothyronine taken through dietary supplements or medication
Diagnosis
Medical history and physical exam
During the exam, your doctor may try to detect a slight tremor in your fingers when they’re extended, overactive reflexes, eye changes and warm, moist skin. Your doctor will also examine your thyroid gland as you swallow to see if it’s enlarged, bumpy or tender and check your pulse to see if it’s rapid.
Blood tests
A diagnosis can be confirmed with blood tests that measure the levels of thyroxine and TSH in your blood. High levels of thyroxine and low or nonexistent amounts of TSH indicate an overactive thyroid.
Your triglyceride and cholesterol level may also be tested. Low cholesterol and triglycerides can be a sign of an elevated metabolic rate.
Radio iodine uptake test
For this test, you take a small, oral dose of radioactive iodine (radioiodine). Over time, the iodine collects in your thyroid gland because your thyroid uses iodine to manufacture hormones. You’ll be checked after two, six or 24 hours — and sometimes after all three time periods — to determine how much iodine your thyroid gland has absorbed.
A high uptake of radioiodine indicates your thyroid gland is producing too much thyroxine. The most likely cause is either Graves’ disease or hyperfunctioning nodules. If you have hyperthyroidism and your radioiodine uptake is low, this indicates that the thyroxine stored in the gland is leaking into the bloodstream and indicates you may have thyroiditis.
Knowing what’s causing your hyperthyroidism can help your doctor plan the appropriate treatment.
Thyroid scan
During this test, you’ll have a radioactive isotope injected into the vein on the inside of your elbow or sometimes into a vein in your hand. You then lie on a table with your head stretched backward while a special camera produces an image of your thyroid gland on a computer screen.
The time needed for the procedure may vary, depending on how long it takes the isotope to reach your thyroid gland.
Ultrasound
Ultrasounds can measure the size of the entire thyroid gland, as well as any masses within it.
References
http://www.mayoclinic.org/diseases-conditions/hyperthyroidism/basics/symptoms/con-20020986
http://www.mayoclinic.org/diseases-conditions/hyperthyroidism/basics/tests-diagnosis/con-20020986
