Thyroid Hormone Levels
Measuring the thyroid stimulating hormone (TSH) levels is used to test thyroid function.#
- A high TSH level suggests that the thyroid gland is not producing enough thyroid hormone (primary hypothyroidism).
- A low TSH level usually suggest that the thyroid is producing too much thyroid hormone (hyperthyroidism).
- The total thyroxine (T4) hormone measures both bound and free thyroxine levels in the blood.
- Free T4 (FT4) measures the free thyroxine hormone, which is not bound and able to freely enter and affect body tissues.
- Triiodothyronine (T3) levels measures the bound and free fractions of triiodothyronine.
Adult range of thyroid hormone levles#
| Type of hormone | Normal levels |
|---|---|
| TSH | 0.5 - 5.0 mIU/L |
| T4 | 80 - 220 ng/dL |
| FT4 | 0.7 - 1.9 ng/dL |
| T3 | 5.0 - 12.0 μg/dL |
| Laboratory results | Differential Diagnosis |
|---|---|
| High TSH, low thyroid hormone level | Primary hypothyroidism |
| High TSH, normal thyroid hormone level | Subclinical hypothyroidism |
| Low TSH, high thyroid hormone level | Primary hyperthyroidism |
| Low TSH, normal thyroid hormone level | Early or mild hyperthyroidism |
| Low TSH, high thyroid hormone level and subsequent… High TSH, low thyroid hormone level | Thyroiditis (Thyroid Inflammation) |
| Low TSH, low thyroid hormone level | Pituitary disease |
Related Pages#
- Medical Disorders
- Oral Health Care Considerations