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HelpThyroid Stimulating Hormone (TSH) Reflex (Thyroid Function Cascade)
Additional Codes
Includes:
-
Thyroid Stimulating Hormone (TSH)
-
Thyroxine (T4), Free
-
Triiodothyronine (T3), Free
Performing Lab(s)
Memorial-Belleville & Memorial-Shiloh
Specimen Requirement (s)
Specimen: plasma
Type: Container/Tube: Mint green (LiHep) tubes
Specimen Volume: 2 mL each
Specimen Minimum Volume: 1 mL of plasma
Collection Instructions: NA
Lab instructions: NA
Unacceptable Conditions
- Avoid Hemolysis.
Day(s)/Shift(s) Test Set Up and Turnaround Time
Sunday through Saturday
Hours: 24 hours
Turnaround Time:
STAT: 60 minutes
Routine: less than 8 hours from receipt
Transport and Stability
Transport temperature: Ambient to lab
Reference Values
TSH
|
Age |
Reference Values |
|
0 – 4 days |
1 – 25 mcIUnit/mL |
|
4 – 30 days |
0.5 – 10 mcIUnit/mL |
|
>30 days |
0.3 – 4.2 mcIUnit/mL |
If TSH is <0.3 mcIU/mL, a T4, Free is automatically performed.
T4, Free
|
Age |
Reference Values |
|
0 – 4 days |
1 – 3 ng/dL |
|
4 days – 30 days |
0.8 – 2.2 ng/dL |
|
>30 days |
0.9 – 1.7 ng/dL |
If T4, Free is <1.7 ng/dL, a T3, free is automatically performed.
| Age | Reference Values |
| 0-18 years | None |
| >18 years | 2-4.4 pg/mL |
CPT/LOINC Codes
84443-TSH
84439-Free T4 (if appropriate)
84481- Free T3 (if appropriate)