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Test Code TSHCA Thyroid Function Cascade , Serum

Important Note

Note: Specimen Requirement Change effective 3/6/24

Additional Codes

Ordering Mnemonic
TSHCA

 

Methodology

Chemiluminescence

Reflex Information:

1. If TSH is <0.10, a Free T4 is reflexed. If the FT4 is normal, a T3 total is reflexed.

2. If the TSH is 0.10-0.33, a Free T4 is reflexed.

3. IF the TSH is 0.34-5.10, no further testing is reflexed.

4. If the TSH is >5.10, a Free T4 and a TPO Antibody is reflexed.

Performing Laboratory

Holland Hospital Laboratory Services

Specimen Requirements

Serum

Container/Tube: Serum gel tube

Specimen Volume: 1 mL of serum

Collection Instructions:

Note: 1. Indicate serum.

2. Label specimen appropriately (serum).

Specimen Transport Temperature

Refrigerate ≤48 hours/Frozen OK

Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding

84443 (HH Bill Code 0205350) TSH

84439 (HH Bill Code 0205652) T4 free (if appropriate)

86376 (HH Bill Code 0205640) TPO (if appropriate)

Reference Values

0.34-5.1 µIU/mL