Test Code T3T T3, Total (Triiodothyronine)
Additional Codes
ALAB: T3T
Powerchart: T3, Total
MA Cerner: T3 Total
Specimen Requirement
1.0 mL Serum or heparin plasma.
Additional Specimen Collection Information
Collection Instructions:
• Minimum volume: 500 mcL serum or heparin plasma
• Hemolysis: does not interfere with this assay
• Lipemia: does not interfere with this assay
• Icterus: No significant interference noted at 10
mg/dL.
• Storage: Store at room temperature for up to 8 hours.
If specimens are stored longer than 8 hours keep refrigerated
(2-8C) until transport to the lab.
Reference Value
0.9-1.8 ng/mL
Performance
Testing is performed Monday through Sunday.
Routine: Typically completed within 4 hours after the specimen
arrives at the testing site.
STAT: Typically completed within 1 hour after the specimen arrives
at the testing site.
CPT Code Information
84480
Test Method
Two-Site Immunoassay; Beckman
Useful For
The clinical importance of Total T3 determination is in the diagnosis of thyroid disorders. Elevated concentrations of T3 can be found in Grave’s disease, and most other classical causes of hyperthyroidism. Decreased concentrations occur in primary hypothyroid diseases such as Hashimoto’s thyroiditis and neonatal hypothyroidism or secondary hypothyroidism due to defects at the hypothalamo-hypophyseal level.