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Endocrinologist

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The causes of increase and decrease of free thyroxine

Alexey Portnov, medical expert
Last reviewed: 19.10.2021

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Diseases and conditions in which the concentration of cT ₄ (thyroxine) in the blood serum changes

Increase in concentration

Hyperthyroidism
Acute thyroiditis
Pregnancy
Obesity
Hepatitis
The use of estrogens (oral contraceptives), thyroid drugs, heparin, imidazole derivatives

Reduction in concentration

Hypofunction of the thyroid gland (myxedema)
Increased protein loss (kidney syndrome)
Isenko-Cushing syndrome
Androgen therapy
Significant deficiency of iodine
Exercise stress
Pangypopituitarism
Loss of protein through the digestive tract
The use of glucocorticosteroids, reserpine, sulfonamides, penicillin, potassium iodide
Resection of the thyroid gland
Thyroid cancer
Overdose of thyrostatics