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Test Code TSH Fl FT4 TSH Reflex to Free T4 Level 

Clinical System Name

TSH Reflex to Free T4 Level 

Sample Requirements

Specimen: Whole blood

Container(s): Gold SST, Red, Gold Microtainer

Preferred Vol: 3.0 mL

Minimum Vol: 2.0 mL



Processing Instructions

Reject due to: gross lipemia

Spin: Y

Aliquot: Y

Temp: 2-8 C

Storage location: CPA refrigerator, FrigD rack. Serum should be removed from separator for storage.

Note: Minimum volume of 1.0 mL serum may be shared with TSH, T3, T4, free T3, and free T4


Off-site collection: Spin blood. Transfer serum/plasma to plastic aliquot container. Refrigerate.


Specimen Type Temperature Time
gel separator with serum Refrigerated 48 h
separated serum Room temp 2 h
  Refrigerated 7 d
  Frozen -20 C 4 w



STAT Performed TAT
N M-Sa, day shift 1-3 d


Performing Laboratory

Seattle Children's Laboratory    


Department:  Chemistry

Location: Chem West

Phone Number:  (206) 987-2617




Reference Range




 Critical High


Birth - 3 days  1.0 - 20.0  25.0 
3 days - 1 month  0.5 - 6.5  10.0 
 1 - 5 months  0.5 - 6.0     
5 months - adult  0.5 - 4.5     



Method: Chemiluminescence by Vitros 3600, third generation assay

Analytical Volume: 0.200 mL serum/plasma

Limitations: Turbidity may affect results.

CPT Codes