Thyroid Stimulating Hormone (TSH)

TSH is made by the pituitary gland to drive the thyroid. When the thyroid slows down, TSH rises to push it; when the thyroid is overactive, TSH falls.

Signs of an underactive thyroid: tiredness, weight gain, feeling cold, hair loss and constipation. Overactive: palpitations, nervousness, weight loss and tremor. If the result is abnormal, the doctor adds Free T4 and Free T3.

Preparation before the test

• No fasting needed; it can be done any time.
• If you take thyroid medicine (levothyroxine), give the sample before the morning dose.
• Stop biotin (B7) supplements 48 hours before; it affects the result.

This information is for awareness only and is not a substitute for medical advice — your treating doctor interprets the result for your case.