Related Experiment Videos
T4 thyrotoxicosis with normal or low serum T3 concentration.
Australian and New Zealand Journal of Medicine
|October 1, 1975
Summary
In sick patients, high thyroxine (T4) with low triiodothyronine (T3) may not indicate thyrotoxicosis. Further tests are needed, as T3 levels may not reliably screen for thyroid issues in the ill or elderly.
Area of Science:
- Endocrinology
- Thyroid Disorders
Background:
- Thyroid hormone levels (T4 and T3) are crucial for diagnosing thyroid conditions.
- Non-thyroidal illness can affect thyroid hormone metabolism and measurements.
Purpose of the Study:
- To investigate thyroid hormone profiles in patients with elevated T4 and normal/low T3.
- To evaluate the diagnostic utility of T3 measurements in sick patients.
Main Methods:
- Radioimmunoassay measurement of plasma T4 and T3 concentrations.
- Clinical assessment of patients with non-thyroidal illness and potential thyroid dysfunction.
Main Results:
- Eight patients presented with high T4 and normal/low T3.
- Six patients had severe non-thyroidal illness; two cases were fatal.
- Two relatively healthy patients with this profile had acromegaly.
Conclusions:
- Elevated T4 with normal/low T3 in sick patients may indicate impaired T4 to T3 conversion, not necessarily thyrotoxicosis.
- Serum T3 may not be a reliable screening test for thyrotoxicosis in the sick or elderly.
- Further investigation, including TRH testing, is necessary for diagnosing thyrotoxicosis in these cases.