Hypercalcemia

Introduction

• An increase in serum calcium level
• Mechanisms and pathophysiology
  • dietary causes
    • calcium ingestion (milk-alkali syndrome)
    • hypervitaminosis D
    • hypervitaminosis A
  • pharmacologic causes
    • thiazides
      • causes increased distal tubule reabsorption of calcium
      • used to treat hypercalciuria
  • malignancy-associated causes
    • Paget’s disease 
      • typically does not result in hypercalcemia
      • can be come hypercalcemic if patient is immobilized
    • squamous cell cancer of the lung
      • ectopic production of PTH (PTH related peptide – PTHrP)
    • multiple myeloma 
      • production of IL-1 activates osteoclast-driven bone resorption
  • sarcoidosis 
    • granulomatous macrophages produce 1α-hydroxylase which produces high amounts of 1,25 vitamin D 
  • hyperparathyroid 
  • genetic causes
    • familial hypocalciuric hypercalcemia
      • defect in calcium sensor of parathyroid gland 
        • there is a loss of negative feedback on PTH by hypercalcemia
        • PTH levels are normal to high despite high serum calcium levels
      • urine excretion of calcium is low
        • key feature distinguishing primary hyperparathyroidism from FHH
  • other causes
    • hyperthyroid
    • Addison’s disease 
• Zollinger-Ellison syndrome 

Presentation

• Symptoms 
  • CNS
    • confusion
    • stupor
    • weakness
  • gastrointestinal
    • constipation
    • anorexia
    • nausea
    • vomiting
  • kidney
    • polyuria
    • kidney stones
    • polydipsia
• Physical exam
  • weakness
  • decreased/absent reflexes
• EKG
• shortened QTc interval 

Treatment

• Conservative
  • hydration
    • saline diuresis
• Pharmacologic
  • loop diuretics
  • bisphosphonates
  • mithramycin
  • calcitonin
  • galium nitrate
• Other
  • dialysis