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HelpTest Code TSH or LAB129 Thyroid-Stimulating Hormone (TSH), Serum or Plasma
Specimen Requirements
| Container Type: |
Optimal: Gold or Mint* *For STAT requests |
|
Acceptable: Red or Green |
|
| Optimal Collection Volume: |
4.5mL; full tube |
| Minimum Volume: |
1 mL whole blood |
| Collection Instructions: |
Gently invert the sample 5-6 times after collection. |
| Specimen Transport: |
Refrigerate |
| Processing Instructions: |
1. If serum, allow the specimen to clot for 30 minutes. 2. Centrifuge specimen within 2 hours of collection. 3. After centrifugation, specimen tubes without a gel barrier should have the serum or plasma aliquoted to a false bottom container. 4. Keep serum or plasma refrigerated until testing can be performed. |
Specimen Stability
BMH Lab
|
Specimen Type |
Temperature |
Time |
|---|---|---|
|
Serum* |
Refrigerated |
14 days |
|
Room Temperature |
8 days |
|
|
Frozen |
24 months |
*Note: Heparinized plasma in gel separator tubes is less stable than serum and is only suitable for add-on testing up to 2 days following sample collection.
BBC, BLH, BSH Lab
|
Specimen Type |
Temperature |
Time |
|---|---|---|
|
Serum* |
Refrigerated |
7 days |
|
Frozen |
30 days |
Specimen Rejection Criteria
|
Hemolysis |
Mild OK; Moderate OK; Gross Reject |
|
Lipemia |
Mild OK; Moderate OK; Gross Reject |
|
Icterus |
Mild OK; Moderate OK; Gross Reject |
|
Other |
Quantity not sufficient |
Useful For
TSH is a very sensitive and specific parameter for assessing thyroid function and is suitable for early detection or exclusion of disorders in the central regulating circuit between the hypothalamus, pituitary, and thyroid.
Methodology
Roche Cobas - Electrochemiluminescence assay
Reference Ranges
|
Age |
Reference Range and Reporting Units |
|---|---|
|
0-1 year |
1.36-8.80 uIU/mL |
|
1-6 years |
0.85-6.50 uIU/mL |
|
>6 years and adults |
0.27-4.20 uIU/mL |
Note: TSH is available as part of the Thyroid Function Cascade.
Interpretive
In primary hypothyroidism, thyrotropin (TSH, formerly thyroid-stimulating hormone) levels will be elevated. In primary hyperthyroidism, TSH levels will be low.
The ability to quantitate circulating levels of TSH is important in evaluating thyroid function. It is especially useful in the differential diagnosis of primary (thyroid) from secondary (pituitary) and tertiary (hypothalamus) hypothyroidism. In primary hypothyroidism, TSH levels are significantly elevated, while in secondary and tertiary hypothyroidism, TSH levels are low or normal.
Elevated or low TSH in the context of normal free thyroxine is often referred to as subclinical hypo- or hyperthyroidism, respectively.
Thyrotropin-releasing hormone (TRH) stimulation differentiates all types of hypothyroidism by observing the change in patient TSH levels in response to TRH. Typically, the TSH response to TRH stimulation is exaggerated in cases of primary hypothyroidism, absent in secondary hypothyroidism, and delayed in tertiary hypothyroidism. Most individuals with primary hyperthyroidism have TSH suppression and do not respond to TRH stimulation with an increase in TSH over their basal value.
Sick, hospitalized patients may have falsely low or transiently elevated TSH.
Source: Mayo Medical Labs
Day(s) Performed
24/7
Expected TAT
Same day
Performing Laboratory
Bronson Laboratory, Chemistry - Kalamazoo, Battle Creek, Paw Paw, South Haven
Sample Retention Time
7 days
CPT Code
84443
LOINC Code
11580-8