Interpretation of laboratory tests of thyroid function in chronic active hepatitis

Area of Science:

• Endocrinology
• Hepatology
• Internal Medicine

Background:

• Chronic active hepatitis (CAH) is associated with a higher incidence of thyroid disorders than expected.
• Routine thyroid function tests may yield inaccurate results in patients with CAH.

Purpose of the Study:

• To evaluate the reliability of various in vivo and in vitro thyroid function tests in clinically euthyroid patients with CAH.
• To identify the most accurate method for assessing thyroid status in this patient population.

Main Methods:

• Assessed 41 clinically euthyroid patients with CAH and 5 with CAH and concurrent/previous thyroid disease.
• Utilized serum thyroxine, thyroid hormone binding, triiodothyronine, thyrotrophin-releasing hormone tests, and radio-iodine uptake.
• Calculated the free thyroxine index using serum thyroxine and thyroid hormone binding levels.

Main Results:

• Standard thyroid function tests (serum thyroxine, T3, TRH, radio-iodine uptake) provided misleading results in some euthyroid CAH patients.
• The free thyroxine index showed results consistent with clinical assessment in most euthyroid patients and those with thyroid disease.
• Borderline results were observed in two euthyroid patients, later normalizing.

Conclusions:

• Anomalies in protein binding likely explain abnormal thyroxine and thyroid hormone binding levels in CAH patients.
• The free thyroxine index is a more dependable measure of thyroid function in patients with chronic active hepatitis.
• Careful interpretation of thyroid function tests is crucial in patients with chronic active hepatitis.