Dr Rendemo Shitiri
What are thyroid function tests?
Thyroid function tests are a series of blood tests used to measure how well the thyroid gland is working. Available tests include the T3, T4, and TSH.
The thyroid is a small gland located in the lower-front part of the neck just above the Adam’s apple. It’s responsible for regulating many of the body’s functions , such as metabolism, energy generation, and mood ( Behaviour).
The thyroid produces two major hormones: triiodothyronine (T3) and thyroxine (T4). If the thyroid gland doesn’t produce enough of these hormones, you may experience symptoms such as weight gain, lack of energy, and depression. This condition is called hypothyroidism.
Hypothyroidism: Signs and symptoms may include:
Fatigue, Increased sensitivity to cold, Constipation, Dry skin, Weight gain, Puffy face, Hoarseness, Muscle weakness, Muscle aches, tenderness and stiffness, Pain, stiffness or swelling of joints, Heavier than normal or irregular menstrual periods, Thinning of hair, Slow heart rate, Depression and Impaired memory.
If the thyroid gland produces excess hormones, you may experience weight loss, high levels of anxiety, tremors, and a sense of being on a high. This is called hyperthyroidism.
Here’s what you may experience with hyperthyroidism:
Appetite change (decrease or increase),Difficulty in sleeping (insomnia), Fatigue, Frequent bowel movement—perhaps diarrhoea, Heart palpitations, Heat intolerance, Increased sweating, Irritability, Light menstrual periods—perhaps even missed periods, Mental disturbances, Muscle weakness, Nervousness, Problems with fertility, Shortness of breath, Sudden paralysis, Tremor/shakiness, Vision disturbances, Weight loss, Dizziness, Thinning of hair, Itching and hives, Possible increase in blood sugar.
Typically, a doctor who is concerned about the thyroid hormone levels will order broad screening tests, such as the T4 or the thyroid-stimulating hormone (TSH) test. If those results come back abnormal, your doctor will order further tests to pinpoint the reason for the problem.
Understanding your test results
T3 and TSH results
The T4 test and the TSH test are the two most common thyroid function tests. They’re usually done together.
T4 test is known as the thyroxine test. Normal range is 66.00 – 181.0 nmol/L. A high level of T4 indicates an overactive thyroid (hyperthyroidism).
The TSH test measures the level of thyroid-stimulating hormone in the blood. The TSH has a normal test range between 0.27 and 4.20 milli-international units of hormone per litre of blood (mIU/L).
If a person have signs of hypothyroidism and TSH reading above 4.20 mIU/L, you’re at risk for progressing to hypothyroidism. The Doctor will likely want to perform thyroid function tests at least every other year going forward. The Doctor may also decide to begin treating you with medications, such as levothyroxine, to ease your symptoms.
Both the T4 and TSH tests are routinely performed on newborn babies to identify a low-functioning thyroid gland. If left untreated, this condition, called congenital hypothyroidism, can lead to developmental disabilities and result in a condition called Cretinism.
The T3 tests checks for levels of the hormone triiodothyronine. It’s usually ordered if T4 tests and TSH tests suggest hyperthyroidism. The T3 test may also be ordered if one shows signs of an overactive thyroid gland.
The normal range for the T3 is 1.30- 3.10 nmol/L . Abnormally high levels most commonly indicate a condition called Grave’s disease. This is an autoimmune disorder associated with hyperthyroidism.
If the blood tests suggest that the thyroid gland is overactive or underactive, the doctor may order a thyroid uptake test or an ultrasound test. These tests will check for structural problems with the thyroid gland and any tumours that may be causing problems.
If the scan is normal, the doctor will likely prescribe medication to regulate your thyroid activity. They will follow up with additional thyroid function tests to make sure the medicine is working.
