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TSH stands for Thyroid Stimulating Hormone. It is a hormone produced by the pituitary gland in the brain that stimulates the thyroid gland to produce thyroid hormones.
The ultra-sensitive TSH test is a blood test that measures the level of TSH in the blood. It is more sensitive than the standard TSH test and can detect even small changes in TSH levels. The ultra-sensitive TSH test is often used to diagnose and monitor thyroid disorders, such as hypothyroidism (an underactive thyroid) and hyperthyroidism (an overactive thyroid).
Normal TSH levels can vary depending on the laboratory and the assay used for the test, but typically fall between 0.4 and 4.0 milli-international units per liter (mIU/L). However, in some cases, a TSH level slightly above or below this range may be considered normal, depending on the individual’s age, gender, and other factors.
If your ultra-sensitive TSH level is higher than normal, it may indicate an underactive thyroid gland, while a lower-than-normal level may indicate an overactive thyroid gland. Your healthcare provider will interpret your test results in the context of your medical history and symptoms to determine the appropriate next steps.
Specimen Requirements
Specimen Requirements
Specimen
Serum (preferred) or plasma
Volume
1 mL
Minimum Volume
0.5 mL (Note: Specimen volume does not allow for repeat testing.)
Container
Red-top tube, gel-barrier tube, or green-top (lithium heparin) tube. Do not use oxalate, EDTA, or citrate plasma.
Collection
If a red-top tube or plasma is used, transfer separated serum or plasma to a plastic transport tube.
Storage Instructions
Room temperature
Stability Requirements
Temperature | Period |
---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Citrate plasma specimen; improper labeling
Test Details
Use
Limitations
While the ultra-sensitive TSH test is a valuable tool in the diagnosis and monitoring of thyroid disorders, there are several limitations to consider:
- False results: The ultra-sensitive TSH test may produce false results in certain situations. For example, certain medications, such as corticosteroids or dopamine, can interfere with the accuracy of the test. Additionally, conditions such as pregnancy or non-thyroidal illness may also affect TSH levels, leading to inaccurate results.
- Lack of specificity: While the ultra-sensitive TSH test is highly sensitive, it may not be as specific as other thyroid function tests in identifying the underlying cause of a thyroid disorder. In some cases, additional tests may be necessary to determine whether an individual has hypothyroidism or hyperthyroidism.
- Normal range variation: The normal range for TSH levels can vary depending on the laboratory and the specific assay used for the test. This means that an individual’s TSH level may be considered normal in one laboratory but abnormal in another, leading to confusion or misinterpretation of results.
- Limited utility in certain cases: The ultra-sensitive TSH test may not be as useful in certain situations, such as in the diagnosis of subclinical hypothyroidism, which is characterized by mildly elevated TSH levels but normal thyroid hormone levels. In these cases, other tests, such as measurement of thyroid antibodies, may be necessary to confirm the diagnosis.
In summary, while the ultra-sensitive TSH test is a valuable tool in the diagnosis and management of thyroid disorders, it is important to consider its limitations and interpret results in the context of an individual’s medical history and other thyroid function tests.
Methodology
LOINC® Map
Component Test Code* | Component Chart Name | LOINC |
---|---|---|
000457 | Thyroid Stimulating Hormone | 3016-3 |
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Copyright © 2022 Regenstrief Institute, Inc. All Rights Reserved. To the extent included herein, the LOINC table and LOINC codes are copyright © 1995-2023, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. See https://