Snapshot 55-year-old woman has hypercalcemia discovered as an incidental finding during normal routine physicial examination. A hand radiograph is shown Introduction Increased parathyroid hormone (PTH) production that may be of primary, secondary or tertiary causes Pathophysiology PTH indirectly stimulates osteoclasts by binding to its receptor on osteoblasts, inducing RANK-L and M-CSF synthesis Epidemiology occurs in 0.1% of the population 90% result form a single adenoma remaining 10% from parathyroid hyperplasia parathyroid carcinoma accounts for less than 1% of all cases Classification Primary typically the result of hypersecretion of PTH by a parathyroid adenoma/hyperplasia may result in osteitis fibrosa cystica breakdown of bone common involves the jaw Secondary secondary parathyroid hyperplasia as compensation from hypocalcemia or hyperphosphatemia ↓ gut Ca2+ absorption ↑ phosphorous associated conditions chronic renal disease renal disease causes hypovitaminosis D leads to ↓ Ca2+ absorption renal osteodystrophy bone leisons due to secondary hyperparathyroidism Tertiary parathyroid glands become dysregulated after secondary hyperparathyroidism secrete PTH regardless of Ca2+ level Serum Ca Serum Phos Serum PTH Primary ↑ ↓ ↑ Secondary normal or ↓ ↑ ↑ Tertiary ↑ ↑ ↑ Presentation Symptoms often asymptomatic weakness kidney stones ("stones") bone pain ("bones") constipations ("groans") uncommon cause of secondary hypertension Evaluation Serology primary hypercalcemia ↑ PTH secondary hypocalcemia/normocalcemia ↑ PTH malignancy ↓ PTH ↑ alkaline phosphatase normal anion gap metabolic acidosis ↓ renal reclamation of bicarbonate Urinalysis primary hypercalciuria (renal stones) ↑ cAMP Radiograph cystic bone spaces ("salt and pepper") often in the skull loss of phalange bone mass ↑ concavity (see key image of this topic) EKG shortened QT Treatment Acute hypercalcemia IV fluids Loop diuretics Symptomatic hypercalcemia is treated surgically treat with parathyroidectoy complications include post-op hypocalcemia manifests as numbness, tingling, and muscle cramps should be treated with IV calcium gluconate Complications Peptic ulcer disease ↑ gastrin production stimulated by ↑ Ca2+ Acute pancreatitis ↑ lipase activity stimulated by ↑ Ca2+ CNS dysfunction anxiety, confusion, coma result of metastatic calcification of the brain