What are the clinical indications for initiating dialysis in kidney failure, including thresholds for hyperkalaemia, metabolic acidosis, refractory fluid overload, uremic symptoms, and hyperphosphatemia?

Indications for Dialysis Initiation

Dialysis should be initiated based on clinical symptoms and complications—not on GFR or laboratory values alone—with specific indications including uremic symptoms (pericarditis, encephalopathy, intractable nausea/vomiting, bleeding diathesis), refractory volume overload, uncontrolled hypertension despite maximal therapy, severe hyperkalemia unresponsive to medical management, severe metabolic acidosis, and protein-energy malnutrition persisting despite nutritional intervention. 1, 2

GFR Thresholds: When NOT to Start Dialysis

• Conservative management should continue until GFR falls below 15 mL/min/1.73 m² unless specific clinical indications mandate earlier initiation 1, 2
• The theoretical target GFR for initiation is approximately 10 mL/min/1.73 m², with mean actual initiation at 9.8 mL/min/1.73 m² (ranging 7-9 for young/middle-aged adults, 10-10.5 for children and elderly) 1, 2
• Early dialysis initiation (GFR >10 mL/min/1.73 m²) provides no survival benefit and may cause harm, as demonstrated by the IDEAL randomized trial 1, 2, 3, 4
• When corrected for lead-time bias, there is no clear survival advantage to starting dialysis at higher versus lower GFR levels 1, 2

Absolute Clinical Indications for Dialysis (Symptom-Driven)

Uremic Symptoms

• Pericarditis (uremic pericardial friction rub or effusion) 1, 2, 5, 6
• Uremic encephalopathy (altered mental status, asterixis, seizures attributable to uremia) 1, 2, 5, 6
• Intractable nausea and vomiting refractory to antiemetic therapy 1, 2, 5, 6
• Bleeding diathesis due to uremic platelet dysfunction 1, 2, 5, 6

Volume and Hemodynamic Complications

• Refractory volume overload despite maximal diuretic therapy (persistent pulmonary edema, peripheral edema, dyspnea) 1, 2, 5, 6, 4
• Uncontrolled hypertension despite maximal medical management 1, 2, 5, 6

Metabolic Derangements

• Severe hyperkalemia (typically >6.5 mEq/L or any level with ECG changes) unresponsive to medical therapy including dietary restriction, diuretics, potassium binders, and insulin/dextrose 1, 2, 5, 6, 7, 4
• Severe metabolic acidosis (typically pH <7.20 or bicarbonate <10 mEq/L) refractory to oral alkali therapy 1, 2, 5, 6, 7, 4
• Severe hyperphosphatemia contributing to high anion gap metabolic acidosis (phosphate >16 mg/dL with acidosis) 7, 8

Nutritional Complications

• Protein-energy malnutrition that develops or persists despite vigorous attempts to optimize protein-energy intake, with no apparent cause other than low nutrient intake 1, 2, 5
• Progressive deterioration in nutritional status: declining edema-free body weight, falling serum albumin, or lean body mass <63% 2

Critical Pitfalls and Caveats

Limitations of GFR-Based Decision Making

• Serum creatinine-based eGFR is unreliable in advanced CKD due to dependence on muscle mass, leading to overestimation of GFR in patients with sarcopenia 1
• In patients with unusual creatinine generation or altered tubular secretion, obtain measured GFR using 24-hour urine collection for creatinine and urea clearances rather than relying on eGFR 1, 2, 5
• Observational studies showing higher mortality with higher eGFR at dialysis initiation reflect patient selection bias—frailer patients with more comorbidities start earlier but don't live as long 1, 2

Risks of Dialysis Itself

• Hemodialysis-related hypotension may accelerate loss of residual kidney function, which is particularly problematic as residual function contributes to quality of life 1, 2, 5, 6
• Dialysis does not replace all kidney functions and imposes significant burden on patient, family, and healthcare system 1, 2, 5, 6
• Vascular access complications (infection, thrombosis) are common—hemodialysis catheter-related bloodstream infections occur at 1.1-5.5 episodes per 1000 catheter-days, affecting ~50% within 6 months 2, 5, 4
• Peritonitis occurs at 0.26 episodes per patient-year, affecting ~30% in the first year of peritoneal dialysis 4

First Dialysis Session Protocol ("Low and Slow")

• Initial session duration: 2-2.5 hours (not full 4 hours) 2, 5
• Reduced blood flow rates: 200-250 mL/min 2, 5
• Minimal ultrafiltration during first session, focusing on clearance rather than fluid removal 2, 5
• Gradual dose escalation over subsequent sessions as tolerated 2, 5
• This approach minimizes dialysis disequilibrium syndrome risk, especially when pre-dialysis BUN exceeds 175 mg/dL 2, 5

When Dialysis Can Be Safely Deferred (Even with GFR <10)

Dialysis may be safely delayed even when GFR <10 mL/min/1.73 m² if ALL of the following are present:

• Complete absence of clinical signs or symptoms attributable to uremia 2
• Stable or increasing edema-free body weight 2, 6
• Adequate nutritional parameters (serum albumin ≥4.0 g/dL or stable if lower) 2, 6
• No refractory volume overload despite optimal diuretic therapy 2, 6
• Blood pressure controlled on medical therapy 2, 6

In the IDEAL trial, asymptomatic patients safely delayed dialysis to eGFR 5-7 mL/min/1.73 m² with careful clinical follow-up 1, 3, 4

Predictors of Earlier Dialysis Need

Certain patients require dialysis at higher GFR levels due to:

• Heart failure (adjusted OR 3.68) 9
• Serum albumin <4.0 g/dL (adjusted OR 2.22) 9
• BUN/creatinine ratio >15 (adjusted OR 1.92) 9
• Hyperuricemia (adjusted OR 1.84) 9

These patients warrant earlier vascular access creation and more intensive pre-dialysis counseling 9

Monitoring Strategy for GFR <15 mL/min/1.73 m²

• Creatinine, eGFR, and potassium: at least monthly, increasing to weekly if rapid progression 6
• Blood pressure: every clinic visit (minimum every 3 months) 6
• Nutritional status (body weight, serum albumin): every 3 months 6
• Continue ACE inhibitor/ARB unless potassium rises >5.5 mEq/L or creatinine doubles—these remain nephroprotective even at GFR <15 6