- Definition of hypocalcemia: A serum calcium of < 8.4 mg/dL with a normal albumin or an ionized calcium of < 4.2 mg/dL.
- First, identify and treat hypomagnesemia if it is present. You have to do this first in order to effectively correct calcium. Hypomagnesemia is a common cause of hypocalcemia because low magnesium induces resistance to PTH and also diminishes PTH secretion.
- Use IV calcium only for patients with severe symptoms of hypocalcemia and a corrected serum calcium of ≤7.5 mg/dL (1.9 mmol/L)
- Use oral calcium therapy for patients with milder symptoms and a corrected serum calcium > 7.5 mg/dL. If po doesn’t work, use IV.
- Also, use IV calcium for patients who cannot take oral treatment.
Severe Acute Hypocalcemia and Symptomatic Hypocalcemia (Treat with IV)
Indications for IV calcium
Parenteral calcium is only necessary if the patient is severely symptomatic or has prolonged QT intervals. Patients with severe symptoms of hypocalcemia such as carpopedal spasm, tetany, seizures, decreased cardiac function, or prolonged QT interval need IV calcium replacement to rapidly correct their hypocalcemia. Treat all asymptomatic patients with an acute decrease in serum corrected calcium to ≤7.5 mg/dL (1.9 mmol/L).
- Severe Symptoms (carpopedal spasm, tetany, seizures)
- A prolonged QT interval, or decreased cardiac function
- Asymptomatic patients with an acute decrease in serum corrected calcium to ≤7.5 mg/dL (1.9 mmol/L)
Calcium gluconate is preferred over Calcium chloride because it is less likely to cause tissue necrosis.
Initial treatment
-Calcium gluconate 1 to 2 g IV in 50 ml D5W (5% dextrose) infused over 10 to 20 minutes. This is the equivalent of 90 to 180 mg of elemental calcium.
**Don’t give calcium more frequently because of the risk of serious cardiac dysfunction, including arrest.
The initial treatment will raise the calcium levels only transiently for 2-3 hours. Give a slow infusion of calcium after that.
Slow infusion
-Calcium gluconate solution that contains 1 mg/mL of elemental calcium. Infuse the solution initially at 50 mL/hour (equivalent to 50mg/hour).
[**The solution with 1mg/ml of elemental calcium is made by adding 11 g of calcium gluconate ( the equivalent of 990 mg of elemental calcium) to normal saline or D5W to get a final volume of 1000ml (1L).]
-Titrate the solution to get a corrected serum calcium concentration at the lower end of the normal range.
-Most patients will need 0.5 to 1.5 mg/kg of elemental calcium per hour.
***Don’t give bicarbonate or phosphate either combined in the same solution or in the same limb at the same time. If the patient needs that, you need to give it through another IV line in a separate limb. You do this to avoid forming insoluble calcium salts.
Chronic hypocalcemia and Mild symptomatic hypocalcemia (treat orally)
Calcium citrate 1500 to 2000 mg of elemental calcium po daily, in divided doses.
Or
Calcium carbonate 1500 to 2000 mg of elemental calcium po daily, in divided doses.