Thyroid Stimulating Hormone (TSH)
- Sample Type
- Serum
- Fasting
- No
- Unit
- uIU/mL
Function
Thyroid Stimulating Hormone (TSH) is a glycoprotein produced by the anterior pituitary gland. Its primary role is to regulate the production of hormones (T3 and T4) by the thyroid gland. The system operates via a negative feedback loop: when thyroid hormone levels in the blood drop, the pituitary releases more TSH to stimulate the thyroid; when hormone levels are too high, the pituitary reduces TSH production.
Why it is Ordered
TSH is the gold-standard screening test for thyroid dysfunction. It is ordered for:
- Hypothyroidism Screening: Symptoms like weight gain, cold intolerance, and depression.
- Hyperthyroidism Screening: Symptoms like weight loss, rapid heartbeat, and anxiety.
- Medication Monitoring: Ensuring patients on Levothyroxine or anti-thyroid drugs are receiving the correct dose.
Associated Conditions
Abnormal TSH levels are linked to several major conditions:
- Hashimoto’s Thyroiditis: An autoimmune condition causing hypothyroidism (High TSH).
- Grave’s Disease: An autoimmune condition causing hyperthyroidism (Low TSH).
- Pituitary Adenomas: Rare tumors that can cause secondary thyroid issues.
- Postpartum Thyroiditis: Inflammation of the thyroid after childbirth.
Check Your Result
Check Your Result
Enter your lab result to see where you stand compared to the standard reference range.
Why Context Matters
TSH levels are highly sensitive to external factors. Biotin (Vitamin B7) supplements are a major confounding factor, often causing falsely low TSH results that mimic hyperthyroidism. Additionally, TSH has a circadian rhythm, peaking at night and reaching its lowest point in the late afternoon. Stress, acute illness ('Euthyroid Sick Syndrome'), and the timing of thyroid medication can all skew results, making a second, morning-fasted sample (without biotin) essential for confirmation.
Lab ranges are statistical averages, not biological laws. "Normal" for a 20-year-old male isn't normal for a 60-year-old female.
Clinical References
Source-of-truth databases and clinical guidelines for Thyroid Stimulating Hormone (TSH):
Official Sources
- ATA Guidelines & Statementsthyroid.org
- Hypothyroidism - StatPearls - NCBI Bookshelfncbi.nlm.nih.gov
Research & Guidelines
Related Indicators
Medically Reviewed by Dr. Binoy Babu, MBBS
Board Certified Doctor • 10+ Years Clinical Experience
Dr. Babu is a practicing physician dedicated to empowering patients with clear, actionable medical information. He founded 2opi to bridge the gap between complex lab reports and patient understanding, ensuring everyone has access to a reliable second opinion.
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