What to do for hypocalcemia?

Management of Hypocalcemia with Serum Calcium of 6.9 mg/dL

For a serum calcium level of 6.9 mg/dL, immediate treatment with intravenous calcium gluconate is necessary, followed by transition to oral calcium supplementation and investigation of the underlying cause. 1, 2

Initial Assessment and Treatment

Immediate Management

• For severe symptomatic hypocalcemia (calcium <7.6 mg/dL):
  • Administer IV calcium gluconate 1-2 mg elemental calcium per kg body weight per hour 1
  • Monitor ionized calcium levels every 1-4 hours during continuous infusion 2
  • Secure a reliable IV line as extravasation can cause tissue necrosis 2

Monitoring During Treatment

• Check ECG for QT prolongation (weakly associated with hypocalcemia) 3
• Monitor for signs of neuromuscular irritability, tetany, and seizures 4
• If patient is on cardiac glycosides, administer calcium slowly with close ECG monitoring due to risk of arrhythmias 2

Transition to Oral Therapy

Once the patient is stabilized and able to take oral medications:

• Transition to oral calcium carbonate 1-2 g three times daily 1
• Add calcitriol (up to 2 μg/day) to enhance intestinal calcium absorption 1
• Continue to monitor serum calcium levels every 4-6 hours initially, then less frequently as levels stabilize 2

Investigation of Underlying Cause

Hypocalcemia at this level requires investigation of the underlying etiology:

1. Check parathyroid hormone (PTH) levels:

   • Elevated or normal PTH suggests hypoparathyroidism 5, 4
   • Low PTH may indicate other causes 5

2. Assess vitamin D status (25-hydroxyvitamin D level):

   • Vitamin D deficiency is a common cause of hypocalcemia 5

3. Check magnesium levels:

   • Hypomagnesemia can contribute to hypocalcemia and impair PTH function 1, 3
   • Correct magnesium deficiency if present

4. Review medication history:

   • Certain drugs can cause hypocalcemia (antiepileptics, aminoglycosides, proton pump inhibitors) 6

5. Evaluate renal function:

   • Acute kidney injury can affect calcium regulation 1, 3
   • In renal impairment, start with lower doses and monitor more frequently 2

Special Considerations

• For patients with CKD, target calcium levels should be 8.4-9.5 mg/dL 1
• Correct total calcium for albumin if albumin is abnormal using the formula:
  • Corrected calcium (mg/dL) = Total calcium (mg/dL) + 0.8 × [4 - Serum albumin (g/dL)] 1
• Calcium gluconate is not compatible with fluids containing phosphate or bicarbonate 2

Pitfalls to Avoid

1. Rapid administration: Can cause hypotension, bradycardia, and cardiac arrhythmias 2
2. Extravasation: Can lead to tissue necrosis and calcinosis cutis 2
3. Overlooking magnesium deficiency: Must be corrected for calcium replacement to be effective 1
4. Inadequate monitoring: Failure to monitor calcium levels during treatment can lead to under or overcorrection 2
5. Missing underlying causes: Treating symptoms without addressing the root cause leads to recurrence 4

Hypocalcemia is extremely common in hospitalized patients (up to 88%) and correlates with severity of illness 3. Prompt recognition and treatment are essential as severe hypocalcemia is associated with increased mortality 7.