Türeoidi

Türeoidi, commonly known as the thyroid gland, is a butterfly-shaped endocrine organ located in the front of the neck, just below the larynx and in front of the trachea. It consists of two lateral lobes connected by an isthmus and is closely associated with nearby parathyroid glands.

The gland produces thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3), which regulate metabolism, growth, development, body temperature, heart rate, and energy use. It also secretes calcitonin, a hormone involved in calcium homeostasis, particularly during childhood. The synthesis of T3 and T4 requires dietary iodine. Hormone release is controlled by the hypothalamic–pituitary–thyroid axis: the hypothalamus releases TRH, the pituitary secretes TSH, and TSH stimulates the thyroid to produce T3 and T4; circulating levels exert negative feedback on the hypothalamus and pituitary.

Anatomically, the thyroid lies anterior to the trachea and below the larynx, with right and left lobes and an isthmus. A pyramidal lobe may be present in some individuals. The parathyroid glands, though adjacent, are separate structures.

Disorders of the türeoidi include hypothyroidism (reduced hormone production, commonly autoimmune Hashimoto’s), hyperthyroidism (excess hormone production, as in Graves’ disease or toxic nodular goiter), thyroiditis, goiter, thyroid nodules, and thyroid cancer. Thyroid nodules may be benign or malignant.

Diagnosis relies on blood tests of thyroid-stimulating hormone (TSH) and free T4/T3, along with imaging such as ultrasound and, when needed, radioactive iodine uptake or biopsy. Treatments vary by condition: hypothyroidism is managed with lifelong levothyroxine replacement; hyperthyroidism with antithyroid medications, beta blockers for symptoms, radioactive iodine, or surgery; nodules and cancer may require biopsy and surgical intervention.