Thyriod Stimulating Hormone (TSH)

CPT Code: 



Serum or Plasma 


0.8 mL 

Minimum Volume:  

0.3 mL (Note: This volume does not allow for repeat testing.) 


Red-top tube or gel-barrier tube



Collection:  If a red-top tube is used, transfer separated serum to a plastic transport tube.

Specimen should be free of particulate matter.  To prevent the appearance of fibrin in serum samples, complete clot formation should take place before centrifugation.   If clotting time is increased due to thrombolytic or anticoagulant therapy, the use of plasma specimen will allow for faster sample processing and reduce the risk of particulate matter.

Blood collected in the presence of oxalate potentially can cause clumping of chrome particles and should not be used.

Frozen plasma samples with insufficient anticoagulants potentially can cause clumping of chrome particles and should not be used.

Reference Range:  


Temperatures  Period 
Room Temperature  24 Hours 
Refrigerated (2-8 ⁰C)  48 Hours 
Frozen (-20 ⁰C)  2 Months 
Note: Mix thoroughly after thawing. Avoid repeated freezing and thawing.



Thyroid stimulating hormone (TSH) is secreted by the pituitary gland and acts on the thyroid gland to stimulate production and release of thyroxine (T4). When the thyroid gland is underactive, TSH levels will be high; low TSH levels signal an overactive thyroid. Various medications can affect the result of this test. 


Causes for Rejection Citrate plasma specimen; improper labeling