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THYROID PANEL (CASCADE)
MessageChemistry
Test Code
LAB5210007
Alias/See Also
Thyroid screen, TSH
CPT Codes
84443
Includes
TSH, Reflex FREE THYROXINE, T3, Thyropereoxidase AB/TPO if indicated
Preferred Specimen
Gold top (serum separator tube)
Minimum Volume
Whole blood: 2 mL (Four full red-top microtainers).
Serum: 900 uL
Serum: 900 uL
Other Acceptable Specimens
Red Top tube acceptable
For babies - collect 3 red microtainers
For babies - collect 3 red microtainers
Instructions
If TSH is abnormal, additional testing will be done. Additional testing might include: T4,Free, T3, Thyroperoxidase Antibodies.
Cascade testing will proceed as indicated below. Allow 2 additional days for completed report.
Note: Lithium Heparin plasma unacceptable (light green top tube).
Algorithm:
Run TSH -> If normal (0.46 - 4.68)-> Stop Testing
Run TSH -> If abnormal (> 4.68) -> Reflex to Free T4 & TPO -> Run T4F & TPO
(Note: TPO Assay is sent to Quest.)
Run TSH -> If abnormal (< 0.46) -> Reflex to Free T4 -> Run T4F
Run T4F -> If T4F > 2.20 -> Stop testing
Run T4F -> If T4F < 2.20 -> Reflex to Total T3 -> Run TT3
Cascade testing will proceed as indicated below. Allow 2 additional days for completed report.
Note: Lithium Heparin plasma unacceptable (light green top tube).
Algorithm:
Run TSH -> If normal (0.46 - 4.68)-> Stop Testing
Run TSH -> If abnormal (> 4.68) -> Reflex to Free T4 & TPO -> Run T4F & TPO
(Note: TPO Assay is sent to Quest.)
Run TSH -> If abnormal (< 0.46) -> Reflex to Free T4 -> Run T4F
Run T4F -> If T4F > 2.20 -> Stop testing
Run T4F -> If T4F < 2.20 -> Reflex to Total T3 -> Run TT3
Specimen Stability
Serum and plasma samples may be stored for up to 7 days at 2–8 °C (36–46 °F) or 4 weeks at -20 °C (-4 °F).
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Do not use turbid specimens. Turbidity in specimens may affect test results.
Plasma is unacceptable for FT4.
Plasma is unacceptable for FT4.
Methodology
Immunometric
FDA Status
Approved
Setup Schedule
Everyday
Report Available
Same day
Limitations
Biotin levels in serum remain elevated for up to 24 hours after oral or intravenous biotin administration.
Heterophilic antibodies in serum or plasma samples may cause interference in immunoassays.These
antibodies may be present in blood samples from individuals regularly exposed to animals or who have been
treated with animal serum products. Results which are inconsistent with clinical observations indicate the
need for additional testing.
Thyroid hormone autoantibodies in samples may cause interference with this test. Results which are
inconsistent with clinical observations indicate the need for additional testing.
The performance of this test has not been established using neonatal specimens.
Heterophilic antibodies in serum or plasma samples may cause interference in immunoassays.These
antibodies may be present in blood samples from individuals regularly exposed to animals or who have been
treated with animal serum products. Results which are inconsistent with clinical observations indicate the
need for additional testing.
Thyroid hormone autoantibodies in samples may cause interference with this test. Results which are
inconsistent with clinical observations indicate the need for additional testing.
The performance of this test has not been established using neonatal specimens.
Reference Range
TSH: 0.46- 4.68 micro IU/mL
Performing Laboratory
Hoag Newport/ Hoag Irvine
