TSH with Free T4 Reflex


Abbrev Code:TSHR   
Order Code:LAB3795Order Name:TSH with FreeT4 Reflex
Synonyms:Thyrotropin, TSH Reflex
Methodology:Roche: Electrochemiluminescence immunoassay (ECLIA)
Vista: Chemiluminescence
Woodwinds: CMIA
CPT Codes: 84443 x1, 84443 x1
Turnaround Time:Varies by site.
Associated Links:

Roche Go Live Schedule



Collection Instructions

Specimen:Blood
Optimal Volume:2.5 mL
Minimum\Peds Volume:0.6 mL
Collection Instructions:Chemistry Tests Containers Chart
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:Roche: 8 days at room temperature; 14 days refrigerated; 24 months frozen. Freeze only once.
Vista: 7 days refrigerated; indefinitely frozen  
Test Performed at or Referral Lab Chemistry  (CSC Maple Grove, Northland, Oxboro Clinic, Range, Roche-Lakes, Roche-Ridges, Roche-St. John's, Roche-UMMC East, Southdale, UMMC/UMMCH-West Bank, 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

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
 
Vista:
Age TSJ
mIU/L
Free T4
F (ng/dL)
Free T4
M (ng/dL)
0-3 d 1.0-20.0 0.93-1.44 0.97-1.87
4-30 d 0.5-6.5 0.81-1.44 0.78-1.52
31 d - 5 mo 0.5-6.0 0.76-1.46 0.76-1.46
6 mo & older 0.4-4.0 0.76-1.46 0.76-1.46


  Roche:
Age TSH F/M
mIU/L
FT4 F/M
ng/dL
0-5 d 0.7-15.2 0.9-2.5
6 d - 2 mo 0.7-11.0 0.9-2.2
3-12 mo 0.7-8.4 0.9-2.0
1-5 y 0.7-6.0 1.0-1.8
6-10 y 0.6-4.8 1.0-1.7
11-19 y 0.5-4.3 1.0-1.6
20 y & older 0.3-4.2 0.9-1.7
 
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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