What are the indications for initiating dialysis in patients with impaired renal function?

Dialysis Indications

Dialysis should be initiated based on clinical symptoms and signs of uremia, evidence of protein-energy wasting, or inability to manage metabolic abnormalities and volume overload—not on a specific GFR threshold alone. 1

Emergent (Absolute) Indications

Initiate dialysis immediately when any of the following life-threatening conditions are present:

• Severe hyperkalemia (>6.5 mmol/L) refractory to medical management (calcium gluconate, insulin with glucose, beta-agonists), as cardiac arrhythmias become imminent at this threshold 2, 3
• Uremic pericarditis, which carries risk of cardiac tamponade and is an absolute indication 2, 3
• Uremic encephalopathy with altered mental status, confusion, seizures, or coma 2, 3
• Refractory pulmonary edema or severe volume overload unresponsive to diuretic therapy causing respiratory compromise 2, 3
• Severe metabolic acidosis refractory to bicarbonate therapy, particularly when pH remains critically low despite medical intervention 2, 3
• Uremic bleeding that cannot be controlled with other measures 3

Urgent Indications

Consider dialysis initiation within hours to days for:

• Progressive uremic symptoms including intractable nausea/vomiting, anorexia, or pruritus that impair quality of life 1, 4
• Severe progressive hyperphosphatemia (>6 mg/dL) with symptomatic hypocalcemia, particularly in tumor lysis syndrome 3
• BUN >75 mg/dL in asymptomatic patients, though clinical trajectory matters more than absolute values 5
• Evidence of protein-energy wasting including declining edema-free body weight, falling serum albumin, or deteriorating nutritional parameters 1

Timing Based on Kidney Function

The KDOQI guidelines provide specific thresholds, though symptoms should drive the decision:

• Weekly renal Kt/Vurea <2.0 (approximating GFR ~10.5 mL/min/1.73 m²) warrants dialysis initiation unless all of the following are present: stable/increasing edema-free body weight, adequate nutrition (albumin above lower limit of normal and stable/rising), and complete absence of uremic symptoms 1
• GFR <15 mL/min/1.73 m² defines kidney failure, though 98% of U.S. patients begin dialysis at this level 1
• Asymptomatic patients with stage 5 CKD may safely delay dialysis until eGFR is 5-7 mL/min/1.73 m² with careful clinical follow-up 4

Critical caveat: Early dialysis initiation (eGFR >10 mL/min/1.73 m²) provides no mortality or morbidity benefit, as demonstrated by the IDEAL study 4. The decision should emphasize symptoms over numerical thresholds 1, 4.

Special Populations

Toxic Ingestions

For ethylene glycol or methanol poisoning, specific thresholds apply:

• Ethylene glycol >50 mmol/L (>310 mg/dL) regardless of antidote availability 2
• Osmolar gap >50 (with fomepizole/ethanol) or >10 (no antidote) 2
• Anion gap >27 mmol/L warrants emergent dialysis; 23-27 mmol/L warrants strong consideration 2

Tumor Lysis Syndrome

• Initiate dialysis for persistent severe hyperkalemia, severe renal impairment, and likely severe metabolic acidosis 6
• Frequent (daily) dialysis is recommended due to continuous metabolite release from ongoing tumor cell lysis 6, 2

Elderly Patients

The decision is more complex in older patients with comorbidities and frailty, as dialysis may worsen outcomes and quality of life 4. Conservative care should be considered when dialysis offers no survival advantage over medical management 7.

Modality Selection

• Intermittent hemodialysis (IHD) is preferred for most emergent indications when hemodynamically stable, particularly for rapid correction of hyperkalemia and toxic ingestions 2, 3
• Continuous renal replacement therapy (CRRT) is mandatory for hemodynamically unstable patients requiring vasopressor support or those with acute brain injury/increased intracranial pressure 2, 3
• Peritoneal dialysis should never be used for emergent indications—it is too inefficient for acute life-threatening complications 2

Critical Pitfalls to Avoid

• Do not rely solely on eGFR or single creatinine values—clinical context including symptom trajectory must guide decisions 2, 4
• Do not delay dialysis in symptomatic patients waiting for a specific GFR threshold, as this increases mortality risk 8
• Patients initiating dialysis for volume overload have 1.69 times higher mortality risk compared to those starting for laboratory decline alone, emphasizing the importance of earlier intervention before severe complications develop 8
• Recognize that creatinine-based eGFR is inaccurate in ESKD patients, making symptom assessment paramount 4

Patient Education and Shared Decision-Making

Patients reaching CKD stage 4 (GFR <30 mL/min/1.73 m²) should receive education about kidney failure treatment options including kidney transplantation, peritoneal dialysis, home or in-center hemodialysis, and conservative treatment 1. The decision to initiate dialysis should be shared between physician, patient, and family members, tailored to individual needs and treatment goals 4, 7.