What are the guidelines for managing electrolyte imbalances in patients with end-stage renal disease (ESRD) requiring dialysis and those with acute kidney injury (AKI) or chronic kidney disease (CKD) not on dialysis?

Electrolyte Management in Dialysis and Non-Dialysis Patients

For Dialysis Patients (ESRD)

Calcium Management in Intensive Hemodialysis

For patients on long or long-frequent hemodialysis (≥5.5 hours per session), use dialysate calcium of 1.50 mmol/L or higher to maintain neutral or positive calcium balance while avoiding predialysis hypercalcemia and PTH oversuppression 1.

• This recommendation is particularly critical for patients who have discontinued calcium-based phosphate binders, as studies show increases in alkaline phosphatase and PTH levels when dialysate calcium remains at 1.25 mmol/L 1.
• Mass-balance studies confirm that 1.5 mmol/L dialysate calcium is required to maintain neutral calcium balance 1.
• Monitor for rising bone alkaline phosphatase and PTH levels, which indicate the need for higher dialysate calcium 1.
• Consider ongoing use of calcium-based phosphate binders, dialysis frequency, and ultrafiltration volumes when determining optimal dialysate calcium 1.

Phosphate Management in Intensive Hemodialysis

Use phosphate dialysate additives to maintain predialysis phosphate in the normal range if hypophosphatemia persists after stopping phosphate binders and liberalizing the diet 1.

• This applies specifically to patients on long or long-frequent hemodialysis who develop hypophosphatemia despite dietary liberalization 1.
• Hypophosphatemia occurs in 60-80% of ICU patients on CRRT and is associated with negative outcomes 2.

Potassium Management in Dialysis Patients

Check serum potassium immediately and place on continuous cardiac monitoring when ESRD patients present after missing dialysis sessions, rather than waiting for symptoms 3.

• Cardiovascular causes account for at least 40% of deaths in ESRD patients, with 20% being sudden cardiac death often triggered by hyperkalemia 3.
• Obtain stat serum potassium, continuous cardiac monitoring, and 12-lead ECG immediately 3.
• Monitor for at least 4-5 hours after any intervention, as arrhythmias can occur during this period 3.
• Severe hyperkalemia (>6.0 mmol/L) requires continuous cardiac monitoring and urgent treatment with insulin/glucose, calcium, and potentially dialysis 3.

For routine dialysis sessions, tailor dialysate potassium concentration to individual patient needs to prevent both hypo- and hyperkalemia 4.

• Potassium removal during dialysis must be carefully controlled, as rapid removal can trigger cardiac arrhythmias 4.
• Use dialysis solutions containing physiological concentrations of potassium (typically 4 mEq/L) to minimize hypokalemia during CRRT 2.

Phosphate Binder Selection

Use sevelamer hydrochloride 800-1600 mg with meals for phosphorus control in CKD patients on dialysis, with dosing based on serum phosphorus levels 5.

• For serum phosphorus >5.5 and <7.5 mg/dL: start with 800 mg (one tablet) three times daily with meals 5.
• For serum phosphorus ≥7.5 and <9 mg/dL: start with 1600 mg (two tablets) three times daily with meals 5.
• For serum phosphorus ≥9 mg/dL: start with 1600 mg (two tablets) three times daily with meals 5.
• Titrate by one tablet per meal at two-week intervals to achieve serum phosphorus ≤5.5 mg/dL 5.

Calcium acetate is an alternative phosphate binder for ESRD patients, with approximately mg-for-mg equivalence to sevelamer 5, 6.

• When switching from calcium acetate to sevelamer: 1 tablet calcium acetate = 1 tablet (800 mg) sevelamer; 2 tablets calcium acetate = 2 tablets sevelamer; 3 tablets calcium acetate = 3 tablets sevelamer 5.

Comprehensive Electrolyte Monitoring in Dialysis

Monitor sodium, potassium, bicarbonate, phosphate, calcium, and magnesium regularly, with frequency based on clinical stability 4, 7.

• The dialysate composition directly impacts electrolyte balance and must be individualized 4.
• Sodium concentration affects interdialytic weight gain and intradialytic hemodynamic stability 4.
• Magnesium monitoring is particularly important with regional citrate anticoagulation, which can cause hypomagnesemia in up to 60-65% of patients 2.

For Non-Dialysis Patients (AKI/CKD)

Acute Kidney Injury Prevention and Monitoring

Use balanced crystalloids instead of 0.9% normal saline for resuscitation to reduce AKI risk and associated electrolyte disturbances 3.

• Hyperchloremia from 0.9% saline can directly cause AKI through decreased kidney perfusion, reduced urine output, and increased extravascular fluid accumulation 3.
• The SALT trial demonstrated that balanced crystalloids reduced 30-day mortality and decreased need for renal replacement therapy 3.
• Limit 0.9% saline use especially in patients with existing acidosis or hyperchloremia 3.

Measure serum urea, creatinine, and electrolytes (sodium, potassium, bicarbonate) at least every 48 hours in patients at increased risk of AKI, or more frequently if clinically indicated 3.

• In critically ill patients with AKI, perform electrolyte monitoring every 6-12 hours 3.
• Severe hyperkalemia (>6.5 mmol/L) can contribute to AKI development 3.

Common Electrolyte Disturbances in AKI/CKD

The most commonly reported electrolyte disturbances in kidney disease are hyponatremia, hyperkalemia, hyperphosphatemia, and hypocalcemia 3.

• Hyperphosphatemia occurs due to reduced renal excretion when renal function deteriorates, leading to secondary hypocalcemia and altered vitamin D metabolism 3.
• Electrolyte disorders are recognized precipitating factors for AKI, particularly in patients with liver disease, sepsis, or critical illness 3.

Special Populations

Patients with cirrhosis require careful volume status assessment and electrolyte monitoring to prevent AKI from dehydration or electrolyte disturbances 3.

Patients undergoing emergency laparotomy are especially susceptible to hypo- and hypernatremia, hypo- and hyperkalemia, hypophosphatemia, hypocalcemia, and hypomagnesemia 3.

Critical Pitfalls to Avoid

• Always rule out pseudohyperkalemia before aggressive treatment, as it can result from hemolysis, inadequate phlebotomy technique, or repeated fist clenching 3.
• Electrolyte disturbances can trigger cardiac dysrhythmias, particularly atrial fibrillation, which may further compromise renal perfusion 3.
• In rhabdomyolysis, hyperphosphatemia occurs acutely and can worsen kidney injury through calcium-phosphate complex deposition in renal tissue 8.
• Avoid sevelamer in patients with bowel obstruction, dysphagia, severe GI motility disorders, or severe constipation 5.