hormone replacement therapy

Hormone replacement therapy means supplying from the outside a hormone the body can no longer make in adequate amounts. When a gland fails or is removed, the chemical messenger it used to broadcast goes silent and its target tissues lose their instructions; replacement therapy restocks that messenger so the downstream organs keep receiving the signal they need.

The guiding aim is physiological replacement — matching, as closely as possible, the amount and pattern the healthy gland once produced. Too little leaves the deficiency uncorrected; too much creates an excess state with its own harms. For some hormones a steady daily dose suffices, while others ideally mimic the body's natural rhythm, such as the higher morning and lower evening pattern of cortisol.

Dosing is usually guided by feedback markers and symptoms rather than guesswork. For thyroid failure, for instance, the dose of thyroid hormone is titrated until the pituitary's TSH returns to its target, confirming the body once again senses a normal supply. Replacement is typically lifelong when the underlying gland cannot recover, and it differs from pharmacological hormone use, where supra-physiological doses are given to treat disease rather than to correct a deficit.