Hypercalcemia

Introduction

Hypercalcemia

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