thyrotoxicosis

An excess of thyroid hormone in the body. Patients have a low level of thyroid stimulating hormone (TSH) in the blood, because the pituitary gland senses that it is enough thyroid hormone.

(Comparison)
• Hyperthyroidism: Increased thyroid hormone synthesis and secretion from the thyroid gland.
• Thyrotoxicosis: Inappropriately high thyroid hormone action in tissues.

(Symptoms)
• Feeling nervous or irritable: Because all of the body's functions are speeding up.
• Fatigue, weight loss, muscle weakness
• Palpitations
• Insomnia
• Hair loss
• Heat intolerance: Feeling overheated when the temperature rises. Often causes heavy sweating.
• Irregular menses in women

(Causes)
• Graves' disease
• Toxic adenoma
• Toxic multinodular goitre
• Exogenous thyroid hormone
• Painless postpartum lymphocytic thyroiditis
etc.

(Treatment)
• Antithyroid drugs
- methimazole, carbimazole (pro-drug for methimazole): Inhibits thyroperoxidase (enzyme) in the thyroid hormone synthesis, oxidizing the anion iodide (I−) to iodine (I2), hypoiodous acid (HOI), and enzyme linked hypoiodate (EOI), facilitating iodine's addition to tyrosine residues on the hormone precursor thyroglobulin.
- propylthiouracil: In the thyroid, inhibits thyroperoxidase (enzyme). In the target tissues, inhibits 5'-deiodinase (enzyme) and decreases peripheral conversion of T4 (thyroxine) to T3 (triiodothyronine).
• Beta-adrenergic antagonists: propranolol, atenolol, metoprolol, nadolol
• Radioactive iodine (Iodine-131): Taken in an oral capsule form and damage or destroy thyroid cells through radiation.
• Thyroidectomy (surgical treatment)