CPT Code: 84443
Order Code: C157
ABN Requirement: No
Synonyms: TSH, Thyrotropin
Specimen: Serum
Volume: 1.0 mL
Minimum Volume: 0.7 mL
Container: Gel-barrier tube (SST, Tiger Top)
Collection:
- Collect and label sample according to standard protocols.
- Gently invert tube 5 times immediately after draw. Do not shake.
- Allow blood to clot 30 minutes.
- Centrifuge for 10 minutes.
Special Instructions: Specimen collection after fluorescein dye angiography should be delayed for at least 3 days. According to the assay manufacturer Siemens: “Samples containing fluorescein can produce falsely depressed values when tested with the Advia Centaur TSH assay.” For patients on hemodialysis, specimen collection should be delayed for 2 weeks.
Transport: Store serum at 2°C to 8°C after collection and ship the same day per packaging instructions included with the provided shipping box.
Stability:
Ambient (15-25°C): 7 days
Refrigerated (2-8°C): 7 days
Frozen (-20°C): 28 days
Causes of Rejection: Specimens other than serum; improper labeling; samples not stored properly; samples older than stability limits
Methodology: Immunoassay (IA)
Turn Around Time: 1 to 3 days
Reference Range:
| Adults | mIU/L |
| ≥20 years | 0.40-4.50 |
| Pregnancy | mIU/L |
| First Trimester | 0.26-2.66 |
| Second Trimester | 0.55-2.73 |
| Third Trimester | 0.43-2.91 |
| Premature Infants (28-36 weeks) | mIU/L |
| 1st Week of Life | 0.20-27.90 |
| Pediatric/Term Infants (>37 Weeks) | mIU/L |
| 1-2 days | 3.20-34.60 |
| 3-4 days | 0.70-15.40 |
| 5 days-4 weeks | 1.70-9.10 |
| 1-11 months | 0.80-8.20 |
| 1-19 years | 0.50-4.30 |
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, Free T4 or Total T4 testing should be considered.
Priority Values:
| Age | Priority 2 (mIU/L) |
| ≤1 year | ≥40.00 |
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.
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.