How Often Should You Get a Thyroid Blood Test?

The thyroid gland produces two important hormones, T3 (triiodothyronine) and T4 (thyroxine), which are concerned with metabolism. Malfunctioning of the thyroid gland manifests either in the form of overproduction or underproduction of hormones. When the hormone levels are above normal, the condition is known as hyperthyroidism and when they are abnormally low, it is called hypothyroidism.


Hypothyroidism usually affects middle-aged and older people. It shows up in the following symptoms, depending on how severe the deficiency is: fatigue and weakness, weight gain, cold intolerance, memory loss, dry skin, constipation, depression, muscle aches and joint pain, swelling, or stiffness, thinning hair and brittle nails, increase in blood cholesterol levels

In infants, the symptoms (which may be few in number) include yellowing of the skin and eyes, frequent choking, a protruding tongue, and a puffy face. They also have constipation, sleepiness, and muscle tone problems.

Children and teenagers experience stunted growth, delayed development of permanent teeth, delayed puberty and poor mental development.


This disorder may be caused by an overactive thyroid. The most common cause of hyperthyroidism is an autoimmune disorder called Graves’ disease. Symptoms include high metabolic rate which leads to a high heart rate, high blood pressure and hand tremors. Other symptoms are frequent bowel movement, swollen thyroid gland, exophthalmos (prominent eyes), weight loss, irregular menstrual cycle, increased appetite, nervousness and restlessness, nausea, lack of concentration, hair fall, and difficulty sleeping.

Why is it important to get tested?

If left untreated, hypothyroidism can lead to further complications such as Goitre, Heart problems, mental health issues, peripheral neuropathy, myxedema, infertility and birth defects. Only through tests can the disorder be spotted early enough to avoid complications and to detect possible causes that can be serious.

Early diagnosis of hyperthyroidism and treatment help to avoid complications due to a condition like Graves’ disease which gets worse over time and becomes life-threatening. Hyperthyroidism can also lead to atrial fibrillation (a common but dangerous type of heart arrhythmia or irregular heartbeat that interrupts flow of blood and may lead to strokes) and congestive heart failure.

How is testing done?

A series of blood tests called thyroid function tests is done to measure T3, T4, and TSH (thyroid stimulating hormone secreted by the pituitary gland) and T3RU (resin T3 uptake). The tests for T4 and TSH are usually taken together and are the most common.

The thyroxine (T4) test reveals hyperthyroidism if T4 levels are high. It measures the amount of free T4 (which is not bound to protein) in the blood. The normal range is from 9.0 to 25.0 pmol/l (picomoles/litre).

The thyroid stimulating hormone (TSH) level test shows hyperthyroidism if the reading is abnormally low. Moderately low levels indicate normal thyroid hormone levels. The normal range is from 0.4 to 4.0 mIU/l (milli-international units of hormone/litre of blood). If the reading is above 2.0 mIU/l, there is a risk of hypothyroidism.

If these two tests point towards hyperthyroidism, the T3 test is taken. The normal range is 100 to 200 ng/dl. Any reading above this is considered abnormally high and is most likely an indication of Graves’ disease.

Cholesterol and triglyceride levels are also tested to indicate elevation in the metabolic rate.

If the blood tests show a functional imbalance in the thyroid gland, an ultrasound test is recommended to check for structural problems with the gland, gland activity, and tumours.

These conditions are treated with the help of medication that either stop or stimulate the thyroid gland’s activities. Surgery and radioactive iodine also serve as treatment for hyperthyroidism. A proper diet can prevent these disorders.

A TSH test is done once a year in case of hypothyroidism to check if the levels are within the normal range. The frequency of hyperthyroidism tests (usually TSH and T4) depends on the treatment. In any case, blood test are taken every few weeks in the beginning, and as the treatment stabilises, the frequency is reduced.

All these tests, are available at Apollo Diagnostics. Find your nearest Apollo Diagnostics centre here.

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