Thyroid Function Test

The main hormones produced by the thyroid are thyroxine (T4) and triiodothyronine (T3), collectively called the thyroid hormones.  These hormones control the rate of metabolism or how quickly the body uses energy. 

Hyperthyroidism (overactive thyroid) and can lead to weight loss, abnormal menstrual cycles, increased heart rate and diarrhea.

Is often caused by an overactive thyroid gland or Graves disease, where the immune system mistakenly attacks the thyroid causing it to overproduce thyroxine.

Hypothyroidism (indicates underactive thyroid gland) causing weight gain, dry skin, constipation, tiredness and abnormal menstrual cycles. Hypothyroidism is most often caused by an autoimmune disease that attacks the thyroid.

Refers to swelling of the thyroid gland.  Goiters are usually painless and treatment depends on the size, symptoms, and underlying cause.

Chronic inflammation of the thyroid gland, usually caused by an autoimmune disease where white blood cells mistakenly attack healthy thyroid cells.  

Graves disease
An autoimmune disease in which the thyroid is mistakenly attacked by the immune system and over stimulated, causing hyperthyroidism.

Thyroid cancer
A disease where abnormal cells grow in the thyroid gland.  Thyroid cancer is a fairly uncommon form of cancer that is usually found early and responds well to treatments.

T3 (tri-iodothyronine) ranges from 36.0 to 40.0.
An increased level indicates –
• Hyperthyroidism,
• Thyrotoxicosis
• Hypoproteinemia
• Nephrosis

Decreased levels indicates –
• Pregnancy
• Hypothyroidism
• Birth control pills.

T4 (tetra-iodothyronine) ranges from 7.0 to 9.0.
An increased level indicates-
• Hyperthyroidism
• Thyrotoxicosis, or pregnancy.

 A decreased level might suggest –
• Hypothyroidism
• Myxedema
• Nephrosis

TSH blood testing done –
• Symptoms of weight loss
• Weight gain
• Irregular menstrual cycles
• Tiredness
• Feelings of extreme hot or cold
• Rapid heart rate and other symptoms. 

The level of TSH monitored with the blood testing should be in the range of .5 to 5.0.