Thyroid Levels
The thyroid levels in the blood do not depend on the size of the thyroid gland but are a very accurate indicator of the state of the person's health. Tests that determine the thyroid levels in the blood have well-defined 'normal' ranges and test results falling out of this range are considered abnormal.
Sometimes the thyroid is over-stimulated by antibodies produced by the immune cells within the body (Graves' disease). As a result, the TSH levels are low. In other cases, the thyroid may be blocked or destroyed by antibodies (Hashimoto's Thyroiditis) and the TSH levels become high. Hence, the levels of TSH in the blood are a sure indicator as to the functioning of the thyroid gland.
At most of the US laboratories, the 'normal' TSH levels are between 0.5 to 5 mIU/liter. Recent research has indicated that the upper values of the thyroid level range includes people who actually have mild thyroid disease and it is their higher TSH levels that have skewed the standard distribution curve. This has led the American Association of Clinical Endocrinologists to recommend that doctors should consider treating patients whose test results for thyroid levels (TSH) fall outside the newly defined 'normal range of 0.3 to 3 mIU/liter.
Thyroid Levels
The National Academy of Clinical Biochemistry, which is a part of the Academy of the American Association for Clinical Chemistry (AACC) reported that: "In the future, it is likely that the upper limit of the serum TSH euthyroid reference range will be reduced to 2.5 mIU/L because >95% of rigorously screened normal euthyroid volunteers have serum TSH values between 0.4 and 2.5 mIU/L"
In certain patients, both male and female, research has also found a relationship between low thyroid levels and cholesterol. People who have low thyroid hormone levels in their body frequently also have high levels of cholesterol. When the thyroid levels are corrected, the cholesterol levels may go down.
Danish researchers, while conducting a study, looked at the monthly thyroid levels (that is, T4, T3, free T4 index, and TSH) of 16 healthy men over a period of 12 months, found that each of the individuals had different variations of their thyroid function, around unique levels or so-called “set points.” Each person had his own individual thyroid function and normal thyroid level, and the values fluctuate slightly within their own range.
These findings led the researchers to conclude that a thyroid level measured within a laboratory’s “normal range” is not necessarily normal for a particular individual.