TSH (Thyroid Stimulating Hormone)
What This Test Measures
Measures pituitary hormone that signals the thyroid; the primary screening test for all thyroid conditions.
Preparation
TIMING: Take your thyroid meds as usual the day before, then draw blood first thing in the morning BEFORE taking that day's dose. TSH is highest early AM and drops throughout the day — an afternoon draw can look falsely 'normal.' The thyroid patient community (STTM and others) widely notes that TSH alone is unreliable. Many functional practitioners consider optimal TSH to be 0.5–2.0 mIU/L. For patients on T3 therapy, TSH will be suppressed and is less useful alone — Free T3 and Free T4 are more informative. These notes reflect common practices in thyroid/functional medicine communities and may differ from standard lab guidelines.
Reflects common practices in thyroid, BHRT, and functional medicine communities. This may differ from standard clinical guidelines. Not medical advice — always discuss with your provider.
General guidelines only. Requirements vary by lab and individual. Confirm with your provider before adjusting any medications.
Turnaround Time
Varies by lab
Clinical Notes
Most important first-line thyroid test; 3rd-generation assay standard
ICD-10 Codes
Common diagnosis codes associated with this test. Codes are assigned by your provider.
Self-Pay Pricing
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Uses LabCorp draw centers · Not available in NY, NJ, RI, HI, ND, or VT · Membership may be required
Uses Quest Diagnostics network; generally lowest DTC prices; not available in NY, NJ, RI
Uses Labcorp network; known for supplement company; competitive lab test pricing
Uses both Quest and Labcorp networks; competitive pricing; broad test selection
Uses Quest and Labcorp; strong panel bundling; results in 1-3 days
Uses Quest Diagnostics network; good panel pricing; established DTC provider
Uses Quest and Labcorp; no hidden draw or facility fees; moderate pricing
Labcorp consumer-direct platform; 2,000+ locations; results in 1-3 days
Uses Quest and Labcorp networks; offers both individual tests and discounted panels
Quest Diagnostics consumer-direct platform; results in 1-2 days; 2,100+ locations nationwide
Primarily uses Labcorp network; popular for hormone panels; higher individual test prices
Lab Codes
Proprietary codes used by each lab for this test.
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For informational purposes only
This page is for educational and research purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. ICD-10 and CPT codes are assigned by your healthcare provider. Always consult a qualified healthcare provider before ordering any lab test or making decisions about your health.