TSH

Test Code
899


CPT Codes
84443

Preferred Specimen
1 mL serum


Minimum Volume
0.7 mL


Instructions
Specimen collection after fluorescein dye angiography should be delayed for at least 3 days. For patients on hemodialysis, specimen collection should be delayed for 2 weeks.

According to the assay manufacturer Siemens: "Samples containing fluorescein can produce falsely depressed values when tested with the Advia Centaur TSH Ultra assay."


Transport Container
Plastic screw-cap vial


Transport Temperature
Room temperature


Specimen Stability
Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days


Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Plasma


Methodology
Immunoassay (IA)

Setup Schedule
Set up: Daily; Report available: Next day


Reference Range
Premature Infants, (28-36 weeks)
1st week of life0.20-27.90 mIU/L
   
Term Infants, (>37 weeks)
serum or cord blood1.00-39.00 mIU/L
   
1-2 days3.20-34.60 mIU/L
3-4 days0.70-15.40 mIU/L
5 days-4 weeks1.70-9.10 mIU/L
1-11 months0.80-8.20 mIU/L
1-19 years0.50-4.30 mIU/L
≥20 years0.40-4.50 mIU/L
   
Pregnancy
  First Trimester0.26-2.66 mIU/L
  Second Trimester0.55-2.73 mIU/L
  Third Trimester0.43-2.91 mIU/L
⁠⁠⁠⁠⁠⁠⁠
TSH levels decline rapidly during the first week of life in most children, but may remain transiently elevated in a few individuals despite normal free T4 levels. For proper interpretation of an abnormal TSH from a newborn thyroid screen, a Free T4 by Dialysis (test code 35167) or Total T4 (test code 867) should be considered.


Clinical Significance
For differential diagnosis of primary, secondary, and tertiary hypothyroidism. Also useful in screening for hyperthyroidism. This assay allows adjustment of exogenous thyroxine dosage in hypothyroid patients and in patients on suppressive thyroxine therapy for thyroid neoplasia.



Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153




The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.