TSH with Free T4 Reflex


Abbrev Code:TSHR   
Order Code:LAB3795Order Name:TSH with FreeT4 Reflex
Synonyms:Thyrotropin, TSH Reflex
Methodology:Chemiluminescence
St Johns/St Joseph/Woodwinds: CMIA
CPT Codes: 84443 x1
Turnaround Time:Varies by site.


Collection Instructions

Specimen:Blood
Optimal Volume:2.5 mL
Minimum\Peds Volume:0.6 mL
Container:Green (lithium heparin, gel), St Johns/St Joseph/Woodwinds-Green (lithium heparin, no gel)
Alternate Containers: Green (lithium heparin, no gel), Purple (EDTA), Red (no gel), Red or gold (gel), St Johns/St Joseph/Woodwinds - Red (no gel)
Contraindications:Large doses of biotin (10 mg or more per day) may cause clinically significant interference in TSH levels. If interference is suspected, it is strongly recommended that biotin is discontinued for at least one week prior to retesting.


Processing and Shipping

Specimen Processing:Centrifuge and aliquot 1.25 mL, 0.2 mL minimum. Store in refrigerator.
Shipping Instructions:Ship at refrigerated temperature.
Stability:7 days refrigerated, indefinitely frozen.
Test Performed at or Referral Lab Chemistry  (M Health Maple Grove Clinic, Range, UMMC-East Bank, Oxboro Bloom, Lakes, Ridges, Northland, Southdale, UMMC/UMMCH-West Bank, St. Joseph's, St. John's, Woodwinds)


Interpretive

Critical Range:0-3 years: Greater than 23 mIU/L
Reference Range:
 Grand Itasca, Free T4 (all ages): 0.6-1.6 ng/dL

St Johns/St Joseph/Woodwinds:
Age TSH (M/F) FT4 (M/F)
0-7 d 3.2-21.0 mIU/L 0.7-1.8 ng/dL
7 d & older 0.3-5.0 mIU/L 0.7-1.8 ng/dL
 

All other sites:
TSH
Age
mIU/L
0-3 d 1.0-20.0
4-30 d 0.5-6.5
31 d - 5 mo 0.5-6.0
6 mo & older 0.4-4.0


 
Free T4
Age
Male, ng/dL Female, ng/dL
0-3 d 0.97-1.87 0.93-1.44
4-30 d 0.78-1.52 0.81-1.44
1 mo & older 0.76-1.46 0.76-1.46
Use:

 

TSH
Patients Without Pituitary Disease

 

 

 

 

 

 

 

 

< 0.4

 

0.4-4.0

 

>4.0

¯

 

¯

 

¯

Suspect hyperthyroid

 

No metabolic thyroid disease

 

Suspect hypothyroid

¯

 

¯

 

¯

Free T4

 

No further testing

 

Free T4

 

 

 

 

 

 

Thyroid gland function testing is based upon the normal response of the pituitary gland to decreased or increased levels of thyroid hormones, principally triidothyronine (T3) and thyroxine (T4). Pituitary and/or hypothalamic hypothyroidism may not be detected through this algorithmic approach and requires both TSH as well as FT4 measurements.

 



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