Thyroid Gland: Functions, Hormones & Health Importance

Anatomy & Hormones

Butterfly-shaped gland in the anterior neck. Produces:

• Thyroxine (T4) – prohormone, major secretory product.
• Triiodothyronine (T3) – biologically active form (mostly from peripheral T4 conversion).

Regulation

Hypothalamus (TRH) → Pituitary (TSH) → Thyroid (T4/T3). Negative feedback by T3/T4 on pituitary/hypothalamus.

Systemic Effects

• Basal metabolic rate
• Heart rate & contractility
• Blood pressure
• Body temperature
• GI motility
• Bone turnover
• Fertility & menstrual regularity
• Mood, cognition, energy

Disorders

• Hyperthyroidism: Weight loss, tachycardia, anxiety, heat intolerance, diarrhea.
• Hypothyroidism: Weight gain, fatigue, cold intolerance, constipation, depression.

Thyroid dysfunction is common and treatable. See a doctor for symptoms or screening if at risk.