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HelpTest Code LAB1230008 Thyroid Function Cascade
Useful For
Screening for a diagnosis of thyroid disease
Profile Information
| Test Code | Test Name | Methodology |
Available Separately |
Always Performed |
|---|---|---|---|---|
| LAB129 | Thyroid-Stimulating Hormone (TSH) | Electrochemiluminescence Immunoassay (ECLIA) | Yes | Yes |
Testing Algorithm:
If TSH is normal, testing stops.
If TSH is low, then FT4 is performed at an additional charge.
If TSH is low and the FT4 is low or normal, then FT3 is performed at an additional charge.
If TSH is high, then FT4 and thyroperoxidase antibodies (TPO) are performed at an additional charge.
Reflex Tests
| Test Code | Test Name |
Available Separately |
Always Performed |
|---|---|---|---|
| LAB127 | Free T4 (Thyroxine) | Yes | No |
| LAB137 | Free T3 (Triiodothyronine) | Yes | No |
| LAB858 | Thyroid Peroxidase Antibodies (TPO) | Yes | No |
Performing Laboratory
Bozeman Health Laboratory Services
Specimen Requirements
Specimen Type: Serum or Plasma
Container/Tube: Red top, Gold top, or Light-green top (lithium heparin)
Specimen Volume: 1 mL
Specimen Minimum Volume: 0.5 mL
Specimen Rejection:
- Grossly hemolyzed samples may be rejected.
- Samples should not be taken from patients receiving therapy with high
biotin doses (i.e. > 5 mg/day) until at least 8 hours following the last biotin
administration.
Specimen Transport Temperature
Ambient/Refrigerated
Specimen Stability
| Specimen Type | Temperature | Time |
|---|---|---|
| Plasma or Serum | Ambient | 5 days |
| Refrigerated | 7 days | |
| Frozen | 30 days |
Reference Values
| Test Name | Reference Value |
|---|---|
| TSH | 0.34-4.82 µIU/mL |
| Free T4 | 0.8-1.5 ng/dL |
| Free T3 | 2.0-4.4 pg/mL |
| TPO antibodies | 0.0-34.0 IU/mL |
Day(s) Test Set Up
Monday through Sunday
Test Classification and CPT Coding
84443-TSH
84439-T4, free (if appropriate)
84481-T3, free (if appropriate)
86376-TPO antibodies (if appropriate)