What are the normal levels for TSH, T4 and T3?
Danish researchers conducted an interesting study, looking at the monthly thyroid levels — T4, T3, free T4 index, and TSH — of 16 healthy men with over a period of 12 months. What they found was that each of the individuals had different variations of their thyroid function, around unique levels – or “set points.” Each person had his own individual thyroid function and normal level, and people tended to fluctute slightly within their own range. These findings led the researchers to conclude that a thyroid test result within a laboratory’s reference limits – or “normal range” — is not necessarily normal for a particular individual. In fact, the researchers also concluded that the distinction between subclinical and overt thyroid disease (abnormal serum TSH and abnormal T4 and/or T3) is somewhat arbitrary, because the patient’s normal set point for T4 and T3 within the laboratory reference range is actually illustrative and needs to be taken into account.
