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Calcium and parathyroid disorders encompass a range of conditions affecting calcium homeostasis, including hyperparathyroidism, hypoparathyroidism, and related bone and mineral metabolism abnormalities. These disorders can lead to significant complications including kidney stones, bone disease, neuropsychiatric symptoms, and cardiovascular effects. Early recognition and appropriate management are essential to prevent long-term sequelae.
Parathyroid hormone (PTH) regulates serum calcium through three main mechanisms: increasing bone resorption, enhancing renal calcium reabsorption, and stimulating renal production of active vitamin D (calcitriol). In hyperparathyroidism, excess PTH leads to elevated serum calcium, bone loss, and potential organ damage, while hypoparathyroidism results in hypocalcemia due to insufficient PTH production or action. The complex interplay between PTH, vitamin D, calcitonin, and target organs (bones, kidneys, intestines) maintains calcium homeostasis.
Clinical presentation varies widely from asymptomatic biochemical abnormalities to severe symptomatic disease affecting multiple organ systems. Hypercalcemia may present with "stones, bones, groans, and psychiatric moans" while hypocalcemia typically causes neuromuscular irritability, tetany, and potential cardiac arrhythmias. Laboratory evaluation should include serum calcium (corrected for albumin), phosphorus, PTH, and vitamin D levels, with imaging studies and specialized testing as indicated to determine the underlying etiology and guide treatment decisions.