TSH with FreeT4 Reflex

Sunquest Code:TSHR  
Epic Code:LAB3795Epic Name:TSH with FreeT4 Reflex
Synonyms:Thyrotropin, Reflex; Thyroid Stimulating Hormone; TSHR
Turnaround Time:Varies by site.

Collection Instructions

Optimal Volume:2.5 mL
Minimum\Peds Volume:0.6 mL
Container:Green (lithium heparin, gel) (Green (lithium heparin) on ICE, Green (sodium heparin, no gel) on ICE, Purple (EDTA), Purple (EDTA) on ICE, Red (no gel), Red or gold (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  (University of Minnesota Health Maple Grove Clinics, Range, UMMC-East Bank, Oxboro Bloom, Lakes, Ridges, Northland, Southdale, UMMC/UMMCH-West Bank)


Critical Range:0-3 years: Greater than 23 mIU/L
Reference Range:
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

Age ng/dL
0-3 d 0.97-1.87
4-30 d 0.78-1.52
1 mo & older 0.76-1.46
Age ng/dL
0-3 d 0.93-1.44
4-30 d 0.81-1.44
1 mo & older 0.76-1.46


Patients Without Pituitary Disease









< 0.4










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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