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TSH with Reflex to Free T4
For patients 1 year of age or older, Free T4 will be performed at an additional charge (CPT code(s): 84439) when TSH result exceeds age/gender specific reference range.
2 mL serum
Ensure that complete clot formation has taken place prior to centrifugation. If the specimen is centrifuged before complete clot formation takes place, the presence of fibrin may cause erroneous results. Sample may be drawn in an SST red-top glass tube, but not submitted in this tube.
Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days
Quest Diagnostics Nichols Institute
33608 Ortega Highway
San Juan Capistrano, CA 92690-6130
Set up: Tues-Thurs, Sat a.m.; Report available: 2-4 days
|Premature Infants (28-36 Weeks)|
|1st Week of Life||0.20-27.90 mIU/L|
|Term Infants (>37 Weeks)|
|Serum or Cord Blood||1.00-39.00 mIU/L|
|1-2 Days||3.20-34.60 mIU/L|
|3-4 Days||0.70-15.40 mIU/L|
|5 Days-4 Weeks||1.70-9.10 mIU/L|
|1-11 Months||0.80-8.20 mIU/L|
|1-19 Years||0.50-4.30 mIU/L|
|≥20 Years||0.40-4.50 mIU/L|
|First Trimester||0.26-2.66 mIU/L|
|Second Trimester||0.55-2.73 mIU/L|
|Third Trimester||0.43-2.91 mIU/L|
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.
Reference ranges are provided as general guidance only. To interpret test results use the reference range in the laboratory report.
(The CPT codes provided 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 payer being billed.)
* The tests listed by specialist are a select group of tests offered. For a complete list of Quest Diagnostics tests, please refer to our Directory of Services.