biotech Lab Marker

TSH Blood Test: What Your Thyroid Results Mean

TSH (Thyroid-Stimulating Hormone) is produced by the pituitary gland and controls how much thyroid hormone your thyroid produces. It is the primary screening test for thyroid disorders and is used to diagnose hypothyroidism and hyperthyroidism.

check_circle

Normal Range

0.4 – 4.0 mIU/L

science

Unit

mIU/L

What Your Results Mean

Normal

A normal TSH level means your pituitary gland and thyroid are communicating properly and your thyroid is producing the right amount of hormone for your body's needs.

High

High TSH usually means your thyroid is underactive (hypothyroidism) — your pituitary is sending more signals because the thyroid isn't producing enough hormone. Symptoms include fatigue, weight gain, cold intolerance, and depression.

Low

Low TSH usually means your thyroid is overactive (hyperthyroidism) — producing too much hormone. Symptoms include weight loss, rapid heartbeat, anxiety, and heat intolerance.

Frequently Asked Questions

What is a normal TSH level? expand_more
A normal TSH level is typically 0.4–4.0 mIU/L, though some labs use slightly different ranges. Optimal levels for most people are considered to be 1.0–2.5 mIU/L.
What does high TSH mean? expand_more
High TSH usually indicates hypothyroidism — your thyroid is not producing enough hormone. This is commonly caused by Hashimoto's thyroiditis and is treated with levothyroxine.
What does low TSH mean? expand_more
Low TSH usually indicates hyperthyroidism — your thyroid is overactive. Causes include Graves' disease, thyroid nodules, or excessive thyroid medication.
Should I fast before a TSH test? expand_more
Fasting is not required for a TSH test, but testing in the morning gives the most consistent results as TSH levels naturally fluctuate throughout the day.
biotech

Have a lab test? Get AI-powered results in minutes.

Upload your lab report and receive a detailed, plain-language explanation of every marker.

upload_file Analyse My Results