Secondary hyperparathyroidism

Secondary hyperparathyroidism (SHPT) is a chronic and progressive disorder characterized by elevated serum parathyroid hormone (PTH), parathyroid gland hyperplasia, and disturbances in mineral metabolism, mainly calcium and phosphorus. SHPT is generally caused by diffuse parathyroid hyperplasia in response to prolonged reduced levels of extracellular calcium from various secondary aetiologies. Although it is initially and adaptive response to a variety of stimuli resulting mainly in extracellular hypocalcaemia (vitamin D deficiency, chronic kidney disease, idiopathic hypercalciuria, calcium malabsorption), long-standing SHPT may eventually develop into autonomous HPT (ie, tertiary HPT). Because SHPT is a compensatory mechanism of the parathyroid glands, it commonly resolves with normalization of calcium and phosphorus homeostasis. After excluding reversible secondary aetiologies, first-line treatment of irreversible SHPT (often related to chronic kidney disease) mainly involves medical therapies.