How to treat hypocalcemia and hypokalemia?

Treatment of Hypocalcemia and Hypokalemia

Acute Hypocalcemia Management

For symptomatic hypocalcemia, administer calcium chloride 10% solution 10 mL IV (270 mg elemental calcium) immediately while monitoring ECG for arrhythmias. 1

• Calcium chloride is strongly preferred over calcium gluconate because it delivers 3 times more elemental calcium per volume (270 mg vs 90 mg per 10 mL of 10% solution), resulting in faster correction of ionized calcium levels 2, 1
• Administer slowly over 2-5 minutes with continuous ECG monitoring to detect cardiac arrhythmias, particularly in digitalized patients 2, 1
• For pediatric patients, the dose is 20 mg/kg (0.2 mL/kg of 10% calcium chloride) given by slow IV push for cardiac arrest, or infused over 30-60 minutes for other indications 2

Critical Contraindications and Cautions

• Never administer calcium through the same IV line as sodium bicarbonate - this causes precipitation 1
• Exercise extreme caution when phosphate levels are elevated (>5.5 mg/dL) due to risk of calcium-phosphate precipitation in tissues and organs 1
• Central venous access is preferred; extravasation through peripheral IV can cause severe tissue necrosis 2

Acute Hypokalemia Management

For hypokalemia, administer potassium chloride orally or IV depending on severity, with the understanding that concurrent hypomagnesemia must be corrected first or potassium repletion will fail. 3

• Oral potassium chloride is indicated for hypokalemia with or without metabolic alkalosis, in digitalis intoxication, and in hypokalemic familial periodic paralysis 3
• Reserve controlled-release oral preparations for patients who cannot tolerate or refuse liquid/effervescent preparations due to risk of GI ulceration and bleeding 3
• Discontinue potassium chloride immediately if severe vomiting, abdominal pain, distention, or GI bleeding occurs 3

Special Consideration: Metabolic Acidosis

• In patients with hypokalemia AND metabolic acidosis, use alkalinizing potassium salts (potassium bicarbonate, citrate, acetate, or gluconate) instead of potassium chloride 3

The Critical Magnesium Connection

Before treating refractory hypocalcemia or hypokalemia, always check and correct magnesium levels first - hypomagnesemia causes both conditions through impaired PTH secretion and renal potassium wasting. 1, 4, 5

• Administer magnesium sulfate 1-2 g IV bolus immediately for symptomatic patients with concurrent hypomagnesemia, followed by calcium replacement 1
• Hypomagnesemia impairs PTH secretion and creates end-organ PTH resistance, explaining why calcium supplementation alone fails in these patients 4, 5
• Magnesium deficiency also increases renal potassium wasting by affecting potassium channel activity, making hypokalemia refractory to potassium replacement until magnesium is corrected 4, 5
• For chronic management, oral magnesium oxide 12-24 mmol daily is the preferred formulation for patients with malabsorption or short bowel syndrome 1

Special Clinical Scenarios

Massive Transfusion and Trauma

• Monitor ionized calcium levels continuously during massive transfusion 2, 1
• Hypocalcemia in trauma correlates with citrate in blood products binding calcium, particularly with FFP and platelet transfusions 2, 1
• Citrate metabolism is impaired by hypoperfusion, hypothermia, and hepatic insufficiency - anticipate more severe hypocalcemia in these conditions 2, 1
• Maintain ionized calcium >0.9 mmol/l to preserve cardiac contractility, vascular resistance, and coagulation function 2

Post-Parathyroidectomy ("Hungry Bone Syndrome")

• Measure ionized calcium every 4-6 hours for the first 48-72 hours post-operatively, then twice daily until stable 1
• Initiate calcium gluconate infusion at 1-2 mg elemental calcium/kg/hour if ionized calcium falls below 0.9 mmol/L 1
• Once oral intake is possible, provide calcium carbonate 1-2 g three times daily plus calcitriol up to 2 mcg/day, adjusting to maintain normal ionized calcium 1

Chronic Kidney Disease and Dialysis Patients

• Maintain corrected total calcium in the low-normal range (8.4-9.5 mg/dL) to avoid vascular calcification 1
• Limit total elemental calcium intake to ≤2,000 mg/day from all sources (diet, binders, supplements) 1
• Do not use calcium-based phosphate binders when corrected calcium >10.2 mg/dL or PTH <150 pg/mL on two consecutive measurements 1
• Adjust dialysate calcium concentration (standard 2.5 mEq/L, up to 3.5 mEq/L if calcium supply needed) based on individual patient requirements 1

Chronic Management of Hypocalcemia

• Daily calcium supplementation (calcium carbonate or citrate) plus vitamin D is the foundation of chronic hypocalcemia management 1, 6
• Calcium citrate is superior to calcium carbonate in patients taking proton-pump inhibitors or with achlorhydria - case reports demonstrate prompt resolution of refractory hypocalcemia when switched from carbonate to citrate 7
• Active vitamin D metabolites (calcitriol) are reserved for severe or refractory cases, typically requiring endocrinologist consultation 1
• Target serum calcium in the low-normal range (8.4-9.5 mg/dL) to minimize risk of nephrolithiasis and renal failure from overcorrection 1

Monitoring Requirements

• Regularly monitor pH-corrected ionized calcium, magnesium, PTH, and creatinine concentrations 1
• Intensify monitoring during biological stress periods: surgery, pregnancy, childbirth, infection, or acute illness 1
• For patients with 22q11.2 deletion syndrome (80% lifetime hypocalcemia risk), maintain heightened surveillance during any stress period 1

Drug Interactions Requiring Potassium Monitoring

• RAAS inhibitors (ACE inhibitors, ARBs, aldosterone antagonists) cause potassium retention - closely monitor potassium levels with concurrent use 3
• NSAIDs reduce renal prostaglandin E synthesis and impair the renin-angiotensin system, causing potassium retention - closely monitor with concurrent NSAID therapy 3

Common Pitfalls to Avoid

• Never attempt to correct hypocalcemia or hypokalemia without first checking and correcting magnesium - this is the most common cause of treatment failure 1, 4, 5
• Avoid overcorrection of hypocalcemia, which leads to iatrogenic hypercalcemia, nephrolithiasis, and renal failure 1
• In hypercalcemic patients requiring diuretics, anticipate and monitor for hypokalemia - prevalence reaches 52% in malignancy-associated hypercalcemia 8
• Patients with 22q11.2 deletion syndrome should avoid alcohol and carbonated beverages (especially colas) as they worsen hypocalcemia 1
• Dehydration can inadvertently cause overcorrection of hypocalcemia during treatment 1