Hypercalcemia

Background

• Definition: Total serum Calcium (Ca⁺²) >10.5
• REMEMBER: Most Ca⁺² in the serum is bound primarily to albumin
• In a hypoalbuminemic pt, you can correct the total Ca⁺² level with the formula:
  •  
  • 0.8 x (4 – albumin level) + uncorrected Ca⁺² = corrected Ca⁺²
• Ca⁺² > 12 can cause shortened QT interval; Ca⁺² at high levels can cause 2^nd and 3^rd degree heart block, ventricular arrhythmias, and ST elevations mimicking MI
• Pts with Ca⁺² <12 or chronic moderate hypercalcemia are often asymptomatic
• Severe manifestations uncommon at Ca⁺² <14

Presentation

• “Stones, bones, thrones, belly groans, and psychiatric overtones”
  • Bone pain
  • Polydipsia/polyuria
  • Nausea/constipation
  • Depressed mood/cognitive impairment
  • Decreased level of consciousness

Management

• Step 1: Stop any contributing medications: Ca⁺² supplements, vitamin D, HCTZ
• Step 2: Check PTH! Then check magnesium, phosphorus, total vitamin D.
• Step 3: Determine if PTH is low or normal/high
  • • Normal or ↑ PTH
      • Primary hyperparathyroidism: ↑ Ca⁺² and ↓ PO₄^-3
      • Tertiary hyperparathyroidism (autologous secretion of PTH in CKD/ESRD)
        • PTH often > 800 with ↑ Ca⁺² and ↑ PO₄^-3
      • Familial hypercalciuric hypercalcemia (often asymptomatic, no treatment required)
      • 24-hour urine Ca⁺² < 200
    • ↓ PTH
      • Humoral hypercalcemia of malignancy: PTHrP
      • Malignancy: Bone survey for blastic lesions, skeletal survey for lytic lesions
      • Excess vitamin D intake: 25 hydroxyvitamin D
      • Granulomatous disease: 1,25 dihydroxy vitamin D, 25 hydroxyvitamin D, nl or ACE
      • Milk-alkali syndrome
      • Immobilization
      • Medications (HCTZ)
      • Thyrotoxicosis: TSH
      • Adrenal insufficiency: AM cortisol
• Step 4: Determine if Ca⁺² > 14 (corrected for albumin) or symptomatic and treat accordingly
  • • If Ca⁺²  < 14 and asymptomatic
      • Encourage PO hydration
      • Replete volume with IV normal saline if hypovolemic
      • Address underlying cause as above
    • If Ca⁺²  > 12 with symptoms or Ca > 14
      • Trend Ca q8 hrs, EKG, monitor on telemetry; strict I/Os + foley catheter
      • Replete volume w/ IV NS boluses then start maintenance IVF at ~ 200cc/hr
        • Goal UOP is 100-150cc/hr
      • Add loop diuretic (Lasix) only AFTER patient is volume replete
      • Bisphosphonate:
        • Zoledronic acid 4mg IV (EGFR >60), Pamidronate 90mg IV (EGFR 15-60)
    • If Ca⁺² >14 or neurologic symptoms, consider sub q (NOT intranasal!) calcitonin
      • VUMC: requires approval from an oncology or endocrine attending
        • Page VU/VA endocrine consult fellow to get approval
        • If cancer pt, page malignant heme or solid tumor fellow​​​​​​​