Parathyroid Disorders & Calcium Imbalance

The parathyroid glands regulate calcium balance through parathyroid hormone (PTH), which raises blood calcium by pulling it from bone, increasing kidney reabsorption, and activating vitamin D. Hyperparathyroidism (excess PTH, most often from a parathyroid adenoma) causes hypercalcemia, often remembered by the phrase "bones, stones, groans, and psychiatric overtones" — bone pain and fracture risk from calcium being pulled out of bone, kidney stones, GI symptoms (constipation, nausea, abdominal pain), and psychiatric/cognitive symptoms (confusion, depression, fatigue) — along with cardiac effects like a shortened QT interval and risk of dangerous arrhythmias at very high calcium levels. Severe hypercalcemia is managed with aggressive IV fluid hydration (normal saline) to dilute calcium and promote renal excretion, often alongside a loop diuretic (never a thiazide diuretic, which actually raises calcium further) and, for malignancy-related hypercalcemia, bisphosphonates.