Introduction
- IV calcium is used in replacement and/or cardiac stabilization. Overuse can occur
- Ionized calcium versus serum calcium
- IV calcium is currently on national drug shortage and consideration should be taken prior to ordering
a. Patients with hyperkalemia and hypermagnesemia are commonly given calcium, but calcium is not a
definitive treatment for hyperkalemia or hypermagnesemia
a. Serum (total) calcium represents all calcium in the body, both free and protein bound. This is affected
by albumin stores in the body and can severely underestimate a patient’s true calcium level
b. Ionized (free) calcium represents active calcium in the body. Measuring ionized calcium should be
considered prior to treating hypocalcemia, especially in non-emergent cases
Clinical Detail
| Property | Calcium Chloride | Calcium Gluconate |
|---|---|---|
| Mechanisms | Normalizes myocyte excitability by shifting threshold potential | Agonist at calcium channels to restore normal cardiac function in blockade |
| Formulations | 100 mg/mL (10%) contains 1.36 mEq EC/mL (3x higher than calcium gluconate) | 100 mg/mL (10%) contain 0.465 mEq EC/mL. |
| Administration | IV push in emergent situations over 2-5 minutes. Central line administration recommended | Slow IV push administration over 2-5 minutes. May be given as continuous infusion for hypocalcemia |
| Adverse Effects | Arrythmias, bradycardia, cardiac arrest, syncope, tingling, necrosis of tissue (chloride > gluconate) | Arrythmias, bradycardia, cardiac arrest, syncope, tingling, necrosis of tissue (chloride > gluconate) |
| Drug Interactions and warnings | Extravasation: Calcium is a vesicant, administration into tissue can cause necrosis. Not to be used when patient is in ventricular fibrillation in cardiac resuscitation | Extravasation: Calcium is a vesicant, administration into tissue can cause necrosis. Not to be used when patient is in ventricular fibrillation in cardiac resuscitation |
| Clinical Pearls | Onset of action has been described as “immediate” but can take up to 5 minutes to start to have effects. The duration of action of calcium is 30–60 minutes | Onset of action has been described as “immediate” but can take up to 5 minutes to start to have effects. The duration of action of calcium is 30–60 minutes |
| Use | Indications | Agents | Pearl |
|---|---|---|---|
| Acute/symptomatic hypocalcemia | Acute symptoms and/or ionized calcium < 3 mg/dL. Moderate: Muscle twitching, spasms, tingling, numbness. Severe: cardiac dysrhythmias, seizures | Calcium gluconate — Moderate: 1–4 g IV (infusion preferred); Severe: 1–2 g IV, over 10 minutes — may repeat every 60 minutes until symptoms resolve. Calcium chloride — Moderate: 200 mg–1 g IV (infusion preferred); Severe: 1 g IV, over 10 minutes, may repeat every 60 minutes until symptoms resolve | Chronic asymptomatic hypocalcemia should be treated with oral calcium |
| Hyperkalemia | Potassium > 5.5 mg/dL + EKG changes | Calcium gluconate 1.5–3 g IVP over 2–5 minutes. Calcium chloride (cardiac arrest) 1 g IVP over 2–5 minutes, repeat as necessary | Calcium is used for heart membrane stabilization, NOT for potassium lowering effects. Additional therapy must be used in combination with calcium to lower potassium levels |
| Magnesium overload | Severe cardiotoxicity/cardiac arrest. Mild–moderate: nausea, diarrhea, urinary retention, lethargy, muscle weakness. Severe: hypotension, cardiac abnormalities | Calcium gluconate 1.5–3 g IVP over 2–5 minutes. Calcium chloride (cardiac arrest) 1 g IVP over 2–5 minutes, repeat as necessary | Hypermagnesemia can inhibit parathyroid hormone production leading to hypocalcium, as well as acting as a calcium channel blocking agent at high doses |
Current ACLS guidelines recommend against routine use of calcium in the treatment cardiac dysrhythmias.
Calcium may be used off-label for calcium channel blocker or beta blocker overdoses on a case-by-case basis.
Evidence
| Author, year | Design | Intervention & Comparison | Assessment |
|---|---|---|---|
| Byrnes, 2004 | Randomized, retrospective chart review | Over 38% of calcium levels were classified incorrectly with the corrected serum calcium based on albumin levels as the primary tool of measurement compared to ionized calcium levels. | Ionized calcium testing provides a high level of specificity compared to corrected calcium levels. As a result, it should be the primary lab used to assess calcium status in patients requiring management for calcium imbalance. |
| Peacock, 2018 | Multicenter, Prospective Observational Study | Patients aged 18 and older diagnosed with hyperkalemia were treated with multiple strategies. The most commonly used therapy employed was insulin/dextrose. IV calcium was used 55% of the time and only 4 of 203 cases employed it as a monotherapy option. | Observing major treatments and clinical decision making in multiple U.S. based trauma centers concerning acute hyperkalemia therapy options. Most centers employed at least 3 to 4 combination therapies to treat hyperkalemia. Calcium was almost never used as monotherapy due to its mechanism of action (not potassium lowering) |
Conclusions
Calcium does not directly lower potassium or magnesium. Additional therapies are needed to affect potassium
levels in combination with calcium administration
Routine use of calcium in cardiac dysrhythmias is not recommended
Ionized and serum calcium are not equal; considerations need to be taken when considering a patients’ true
calcium level
Oral replacement of calcium should be considered first line if patients are stable and/or chronic issue
Calcium chloride has a higher risk of extravasation and use should be restricted to cardiac arrest unless a
central line is established
References
Peacock WF, Frank Peacock W, Rafique Z, et al. Real World Evidence for Treatment of Hyperkalemia in the Emergency Department (REVEAL-ED): A Multicenter,
Prospective, Observational Study. The Journal of Emergency Medicine. 2018;55(6):741-750.
Parham WA, Mehdirad AA, Biermann KM, Fredman CS. Hyperkalemia revisited. Tex Heart Inst J. 2006; 33(1):40-47.
Link MS, Berkow LC, Kundenchuck PJ, et al. 2015 American Heart Associated guidelines updated for cardiopulmonary resuscitation and emergency
cardiovascular care. Part 7: adult advanced cardiovascular life support. Circulation. 2015;132:S444-64.
Byrnes MC, Huynh K, Helmer SD, Stevens C, Dort JM, Smith RS. A comparison of corrected serum calcium levels to ionized calcium levels among critically ill
surgical patients. Am J Surg. 2005;189(3):310-314.
High levels of potassium
can a decrease in
resting membrane
potential, causing the
membrane to become
partially depolarized
Calcium restores normal
myocyte excitability by
shifting the threshold
potential to a less
negative value
Normal difference of
resting potential and
threshold potential is
restored, thus stabilizing
the membrane
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