TSH w/Reflex




Test Mnemonic

TSHRF

CPT Codes

  • 84443 - QTY (1)

Performing Laboratory

Cleveland Clinic Laboratories


Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
1 mLPlasmaLithium heparin PST (Lt. Green)AmbientCentrifuge and refrigerate. 

Alternate Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
1 mLSerumSST (Gold)Ambient  

Stability

Environmental Condition Description
Ambient5 days
Refrigerated7 days
Frozen30 days

Days Performed

7 days a week

Turnaround Time

8 hours

Methodology

Name Description
Electro Chemiluminescence Immunoassay (ECLIA) 

Reference Range

TSH
Sex Age From Age To Type Range Range Unit
   Days5 DaysNormal0.700 - 15.200uU/mL
 6 Days90 DaysNormal0.720 - 11.000uU/mL
 4 Months12 MonthsNormal0.730 - 8.350uU/mL
 1 Years6 YearsNormal0.700 - 5.970uU/mL
 7 Years11 YearsNormal0.600 - 4.840uU/mL
 12 Years20 YearsNormal0.510 - 4.300uU/mL
 21 Years99 YearsNormal0.270 - 4.200uU/mL
       Pregnancy first trimester (9-12 weeks): 0.180 - 2.990 uU/mL 
       Pregnancy second trimester: 0.110 - 3.980 uU/mL 
       Pregnancy third trimester: 0.480 - 4.710 uU/mL 

Clinical Info

Produced by the anterior pituitary gland, thyroid-stimulating hormone (TSH) stimulates the thyroid gland to convert iodine and the amino acid tyrosine into the thyroid hormones thyroxine (T4) and triiodothyronine (T3), which in turn regulate metabolism, growth, and development. These free thyroid hormones also work in a negative feedback loop to regulate the amount of TSH that is released from the pituitary gland. Testing for TSH is a highly sensitive indicator for hypothyroidism and an important tool in diagnosing thyroid dysfunction. An elevated TSH result usually indicates an underactive thyroid (hypothyroidism), and a decreased TSH result indicates an overactive thyroid (hyperthyroidism) or excessive amounts of thyroid medication in an individual being treated for hypothyroidism. The latest “third-generation” assays for TSH are sensitive enough to distinguish moderately low but still clinically normal levels of TSH from lower levels indicative of hyperthyroidism. If TSH is abnormal, Free T4 will be performed and billed.