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Test Code T4 T4, LAB126

Performing Laboratory

St. Luke's Hospital Cedar Rapids

Specimen Requirements

Container/Tube:

Prefered:  Green-top (lithium heparin) tube

Acceptable:  Gold-top serum gel tube or plain, red-top tube

Specimen Volume: 0.1 mL of plasma or serum

Stability:  Separated samples stored at 2 – 8°C and analyzed within 30 days

Collection Instructions:

Note: 1. Anti-thyroxine antibodies will interfere with this assay.

2. Human anti-mouse antibodies or other heterophile antibodies may be present in patient specimens. This assay has been specially formulated to minimize the effects of these antibodies, however results from patients known to have these antibodies should be carefully evaluated.

3.  Venipuncture should occur prior to sulfasalazine and/or sulfapyridine administration due to the potential for falsely depressed results.

Reference Values

 

Age Group

Total T4

Neonates

0 - 7 days

8.9 – 31.0 mcg/dL

Neonates

8 - 29 days

13.9 – 41.5 mcg/dL

Infants

1 – 23 months

7.4 – 14.3 mcg/dL

Children

2 years – 12 years

6.8 – 12.5 mcg/dL

Adolescents

13 years – 20 years

6.0 – 11.6 mcg/dL

Adults

≥21 years

4.7 – 13.3 mcg/dL

 

Day(s) Test Set Up

Monday through Saturday

Methodology

Homogeneous Enzyme Immunoassay (EIA)

Useful For

Thyroid funtion

Test Classification and CPT Coding

84436