What is a Thyroid Test?

The results show levels of TSH, T3, T4, F(free)T3, F(free)T4, thyroid antibodies, and calcitonin. 

High TSH and low FT3, FT4 indicate an underactive thyroid, while the converse implies an overactive thyroid. 

Thyroid antibodies and calcitonin values inform the doctor of thyroiditis, type 1 diabetes, or rheumatoid arthritis.

You are likely to be hyper- or hypo-thyroid if you have persistent symptoms such as:

• Anxiety
• Weight gain or loss
• Hand tremors 
• Puffiness 
• Eye-bulging 
• Sleep difficulty
• Constipation 
• Increased heart rate 
• Tiredness 
• Hair loss 
• Low tolerance for cold temperatures
• Irregular menstrual periods 

Your doctor will likely prescribe a thyroid function test under one or more of these symptoms.

The lab technician draws a blood sample from your arm vein and tests it in the laboratory. 

• TSH is measured first, with the normal adult range being 0.40 - 4.50 mIU/mL (milli-international units per millilitre of blood). 
• T3 is measured [normal 100 - 200 ng/dL (nanograms per decilitre)] as is 
• T4 [normal 5.0 – 11.0 ug/dL (micrograms per decilitre)]. 
• The test also measures FT3 and FT4.

Early signs of thyroid problems are often mistaken for other health issues and left undiagnosed. Fatigue, weight gain/loss, slow/increased heart rate, sensitivity to heat/cold, bulging eyes, and bloating are manifestations of a malfunctioning thyroid. 

A doctor connects these maladies to a malfunctioning thyroid. Do consult your doctor soon as any one or more of these signs show up.

About one in eight women develop thyroid problems, the risk being primarily due to diet, pregnancy, and smoking. 

Hypothyroidism or lack of enough thyroid hormones is most common in women. This condition shows up through slower metabolism leading to weight gain, feeling sluggish, tired, and depressed. Irregular periods, dry skin, and nails are other indicators.

The TSH test is the primary blood test to detect thyroid malfunction. An abnormal level of TSH is an “early warning system” – a precursor to the actual level of thyroid hormones in the body becoming too high or too low. T4 and T3 tests (Total and Free), when checked with TSH, more accurately reflect how the thyroid is functioning.

The lab technician collects a blood sample through venepuncture. 

A tightly tied rubber band around the upper arm gets the veins to swell with blood. The technician then finds an appropriate vein, inserts a needle into the vein, and collects the requisite blood in a test tube for laboratory analysis. 

They then loosen the band, withdraw the needle, and cover the prick point with a medicated strip.

A thyroid function test is a simple blood test. Sample collection takes a few minutes, even less than five minutes. 

The laboratory then analyses the blood sample drawn through venepuncture and provides the results. A qualified professional checks and verifies these results and signs the final report. 

The report usually shows the levels of thyroid parameters ascertained with a corresponding normal value range. The results typically come in 1-3 days.

A thyroid blood test requires no special precautions, including fasting. In any event, drinking water does not interfere with the fasting requirements. 

However, if you are on thyroid medication, getting the sampling done before intaking the medicine is advisable. It is best to avoid Biotin (Vitamin B7) for two days before the day of sampling.

Reach us!  Get a free second opinion on your Thyroid profile test by consulting our specialists at Yashoda Hospitals.