What are the next steps for treating hypercalcemia or hypocalcemia?

Management of Hypercalcemia and Hypocalcemia

For hypercalcemia, the next steps include immediate hydration with intravenous saline, discontinuation of calcium-raising medications, and treatment with bisphosphonates for severe cases. For hypocalcemia, treatment involves calcium supplementation, vitamin D therapy, and addressing the underlying cause.

Hypercalcemia Management

Initial Assessment

• Confirm hypercalcemia with corrected calcium calculation:
  • Corrected calcium (mg/dL) = Total calcium (mg/dL) + 0.8 [4 - Serum albumin (g/dL)] 1
• Determine severity:
  • Mild: <12 mg/dL (usually asymptomatic)
  • Severe: ≥14 mg/dL (often symptomatic) 2
• Evaluate symptoms: nausea, vomiting, constipation, mental status changes, dehydration 3

Immediate Management of Severe Hypercalcemia

1. Hydration: Administer intravenous normal saline to correct volume depletion 4, 2

   • Target: Restore urine output to approximately 2 L/day 4
   • Caution: Avoid overhydration in patients with cardiac failure 4

2. Loop diuretics: Consider furosemide after adequate hydration to enhance calcium excretion 3, 5

3. Bisphosphonates for severe hypercalcemia (especially malignancy-related):

   • Zoledronic acid 4 mg IV over ≥15 minutes for hypercalcemia of malignancy 4
   • Dose adjustment needed for renal impairment (see table below) 4

   Baseline Creatinine Clearance (mL/min)	Zoledronic Acid Dose (mg)
   >60	4
   50-60	3.5
   40-49	3.3
   30-39	3

4. Discontinue medications that can cause hypercalcemia:

   • Calcium supplements
   • Vitamin D supplements
   • Thiazide diuretics 2

Management Based on Underlying Cause

• Primary hyperparathyroidism:

  • Refer to parathyroid surgeon if: symptomatic hypercalcemia, severe hypercalcemia, osteoporosis, age <50 years, creatinine clearance <60 mL/min, or nephrolithiasis 6
  • Consider parathyroidectomy for persistent hypercalcemic hyperparathyroidism 1

• Hypercalcemia in CKD patients:

  • Reduce or stop active vitamin D and phosphate supplements 1
  • Maintain serum calcium within normal range (8.4-9.5 mg/dL), preferably toward lower end 1
  • Consider dialysis with low calcium dialysate (1.5-2.0 mEq/L) if hypercalcemia persists 1

• Malignancy-related hypercalcemia:

  • Treat with zoledronic acid 4 mg IV 4
  • Retreatment may be considered if calcium doesn't normalize (minimum 7 days between doses) 4

Hypocalcemia Management

Initial Assessment

• Confirm hypocalcemia with corrected calcium calculation
• Evaluate for symptoms: paresthesia, tetany, seizures, laryngospasm 1
• Check for vitamin D deficiency (25-OH vitamin D levels) 1, 6

Immediate Management of Symptomatic Hypocalcemia

1. Intravenous calcium for severe symptomatic hypocalcemia 5, 7

   • Administer via central venous catheter for severe cases 7
   • Monitor for cardiac effects

2. Oral calcium supplementation for less severe cases:

   • Calcium carbonate is recommended 1
   • Total elemental calcium intake should not exceed 2,000 mg/day 1

3. Vitamin D therapy:

   • For vitamin D deficiency (<30 ng/mL): Ergocalciferol (vitamin D2) supplementation 1
   • Active vitamin D sterols for patients with CKD 1
   • Monitor calcium and phosphorus levels every 3 months 1

Management Based on Underlying Cause

• CKD-related hypocalcemia:

  • Target 25-OH vitamin D levels >20 ng/mL 1
  • Ensure adequate dietary calcium intake 1
  • Evaluate for vitamin D and/or dietary calcium deficiency if PTH is elevated 1

• Post-parathyroidectomy hypocalcemia (hungry bone syndrome):

  • Aggressive calcium and vitamin D supplementation 6
  • Close monitoring of calcium levels 6

• Chronic hypocalcemia:

  • Oral calcium and vitamin D supplements
  • Consider thiazides to reduce renal calcium loss 7
  • For refractory cases, subcutaneous parathyroid hormone 1-84 may be considered 7

Monitoring

• Hypercalcemia:

  • Monitor serum calcium, phosphorus, and renal function
  • Reassess calcium 7 days after treatment with bisphosphonates 4

• Hypocalcemia:

  • Monitor serum calcium, phosphorus, and PTH
  • For patients on vitamin D therapy, check calcium and phosphorus at least every 3 months 1

Special Considerations

• Avoid vitamin D supplements in patients with hypercalcemia 1
• In CKD patients, maintain calcium-phosphorus product <55 mg²/dL² 1
• Consider calcimimetics for severe hyperparathyroidism that fails to respond to conventional treatments 1
• Use cinacalcet with caution due to risk of hypocalcemia and increased QT interval 1

Remember that prompt identification and treatment of the underlying cause is essential for long-term management of calcium disorders.