TSH

Test Code

899

Alias/See Also

1230401593 | LAB129: TSH (Thyroid Stimulating Hormone)

LAB806: General health panel

LAB8021: Metabolic Syndrome Panel

LAB129A: TSH (Thyroxine Stim Hormone)

LAB8024: Endocrine Assessment Panel 2 | QUEST EAP: 899

CPT Codes
84443

Preferred Specimen

1 mL serum

Patient Preparation
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 after angiography. According to the assay manufacturer Siemens: samples containing fluorescein can produce falsely depressed values.

Minimum Volume

0.7 mL

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 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

Pregnancy
First Trimester	0.26-2.66 mIU/L
Second Trimester	0.55-2.73 mIU/L
Third Trimester	0.43-2.91 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

Last Updated: April 21, 2023

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.