Chronic Renal Failure (CRF)

See related article Chronic Kidney Disease and its Management.

Chronic renal failure is usually taken to be synonymous with stage 4 (severe impairment) chronic kidney disease (CKD) or stage 5 CKD (established renal failure) - see the Assessing Renal Function article for information about glomerular filtration rate (GFR).

All stages of CKD²

• Regular measurements of kidney function and other laboratory tests depending on the severity of kidney impairment.
• General health advice: smoking cessation, weight loss, aerobic exercise, limiting alcohol intake, limiting sodium intake.
• Avoidance of nephrotoxins, e.g. IV radiocontrast agents, NSAIDs, aminoglycosides.
• Cardiovascular prophylaxis:
  • For patients with 10 year risk of cardiovascular disease of greater than 20%, consider aspirin treatment (if BP is below 150/90 mmHg) and lipid-lowering drug therapy.
  • Blood pressure monitoring: blood pressure should be measured at least annually.
  • Control of hypertension: hypertension should be tightly controlled. The threshold for initiation of anti-hypertensive medication:
    • If urine protein/creatinine ratio (PCR) is below 100 mg/mmol: threshold 140/90 mmHg, target 130/80 mmHg.
    • If urine PCR is above 100 mg/mmol: threshold 130/80 mmHg, target 125/75 mmHg.
• ACE inhibitor or angiotensin receptor blocker to be started:
  • If urine PCR is above 100 mg/mmol.
  • In diabetic patients with micro-albuminuria.
  • Serum creatinine and potassium should be checked before starting medication, two weeks after starting, and after subsequent increases in dose. If creatinine increases by more than 20% or fall in GFR of more than 15%, repeat creatinine, check potassium and refer for specialist opinion on whether to stop treatment or to investigate for renal artery stenosis.
  • If hyperkalaemia is present (serum K above 6 mmol/l): stop relevant drugs, eg. NSAIDs and potassium-retaining diuretics; check diet and proprietary treatments, e.g. LoSalt. If hyperkalaemia persists the ACE or ARB should be stopped.

Additional management for CKD stage 3 includes²

• Annual measurement of haemoglobin, potassium, calcium and phosphate.
• If Hb below 11 g/dL and other causes excluded, treat with erythropoiesis stimulating agents to maintain Hb 11-12 g/dL depending on the patient's functional needs.
• Request renal ultrasound in patients with lower urinary tract symptoms, refractory hypertension, unexpected progressive fall in GFR.
• Immunise against influenza and pneumococcus.
• Review all prescribed medication regularly to ensure appropriate doses.
• Avoid nephrotoxic drugs including NSAIDs wherever possible.
• Check parathyroid hormone concentration when Stage 3 is first diagnosed: if raised, check serum 25-hydroxyvitamin D and if low, treat with ergocalciferol or cholecalciferol with calcium supplement (not calcium phosphate). Repeat PTH after 3 months and refer if still raised.

Additional management for CKD Stages 4-5 includes²

• Care of all patients with stage 4 or 5 CKD should be discussed formally with a nephrologist even if it is not anticipated that renal replacement therapy will be appropriate. Exceptions may include:
  • Patients with another terminal illness.
  • Patients with stable function in whom all the appropriate investigations and management interventions have been performed and who have an agreed and understood care pathway.
  • Patients in whom further investigation and management is clearly inappropriate.
• 3-monthly tests: serum creatinine (for eGFR), Hb, calcium, phosphate, bicarbonate, parathyroid hormone.
• Dietary assessment.
• Immunisation against hepatitis B.
• Investigation and treatment of phosphate retention and hyperparathyroidism.
• Correction of acidosis.
• Timely provision of dialysis access depending on treatment choice.

Renal replacement therapy

Indications for renal replacement therapy (haemodialysis, peritoneal dialysis, chronic ambulatory peritoneal dialysis or renal transplantation) include:

• Serum creatinine greater than 500 mmol/L.
• Symptoms: pericarditis, encephalopathy, peripheral neuropathy, intractable gastrointestinal symptoms, failure to thrive and malnutrition.
• Severe metabolic acidosis: bicarbonate less than 12 mmol/L.

• Anaemia: left ventricular hypertrophy, fatigue, impaired cognitive functioning
• Coagulopathy
• Hypertension: left ventricular hypertrophy, heart failure, stroke, cardiovascular disease
• Calcium phosphate loading: cardiovascular and cerebrovascular disease, arthropathy, soft tissue calcification
• Renal osteodystrophy: disorders of calcium, phosphorus and bone, most commonly osteitis fibrosa cystica
• Bone changes of secondary hyperparathyroidism: bone pain and fractures
• Neurological: uraemic encephalopathy, neuropathy including peripheral neuropathy
• Dialysis amyloid: bone pain, arthropathy, carpal tunnel syndrome
• Fluid overload: pulmonary oedema, hypertension
• Malnutrition: increased morbidity and mortality, infections, poor wound healing
• Glucose intolerance due to peripheral insulin resistance

• Water and electrolyte balance:
  • Patients with chronic kidney disease pass normal volumes of urine. Precise restriction of fluid intake is only required for patients with oliguria. The usual recommendation is for a daily intake equal to the daily urinary output plus 500 mL (for insensible losses).
  • Patients should avoid binge drinking and be vigilant in replacing extra fluid losses in hot weather and during episodes of diarrhoea or vomiting.
  • Severe acute volume overload may require high dose loop diuretics or dialysis.
  • Dietary restriction to 60 mmol/day each of sodium and potassium is appropriate but compliance is greatly improved with sensible and flexible dietary advice.
  • Loop diuretics (with the addition of a thiazide diuretic if resistant) improve sodium balance and blood pressure.
  • Hyperkalaemia is treated with dialysis if the potassium level rises above 7 mmol/L. Otherwise treatment is directed towards the cause, e.g. excess fruit, chocolate or coffee, gastrointestinal haemorrhage, acidosis or tissue necrosis. Hyperkalaemia with the GFR still above 10 mL/min may be due to hyporeninaemic hypoaldosteronism in patients with diabetes, hypoadrenalism or as a result of treatment with ACE inhibitors.
• Anaemia:
  • Erythropoietin is given with iron. The serum ferritin is monitored throughout treatment and iron is stopped if the ferritin level becomes too high, e.g. above 500 mcg/L.
  • Early erythropoietin therapy may prevent left ventricular hypertrophy.
  • The timing for initiation of treatment remains uncertain. The haemoglobin level is usually maintained at or above 11 g/dL.
• Acidosis:
  • Chronic acidosis aggravates hyperkalaemia, inhibits protein synthesis and accelerates calcium loss from bone.
  • Treated with sodium bicarbonate as long as the patient can tolerate the increased sodium load. Additional sodium may cause fluid overload and worsen hypertension.
• Hyperphosphatemia:
  • Occurs late in chronic kidney disease.
  • Treated with dietary restriction, dietary phosphate binders and calcium carbonate.
• Hypocalcaemia:
  • Prescribe calcium supplements, with or without calcitriol.
• Hyperparathyroidism:
  • Reduce hyperphosphataemia by diet and phosphate binders.
  • Prescribe 1,25-dihydroxycholecalciferol and maintain a normal calcium level.
  • Secondary hyperparathyroidism starts early in chronic renal failure and is difficult to treat when it becomes established.
  • Secondary hyperparathyroidism may lead to tertiary hyperparathyroidism if not treated effectively.
• Malnutrition:
  • Must be avoided, although protein restriction can slow progression of renal failure.
  • Restriction of dietary protein slows the progress of glomerulosclerosis in residual nephrons in animal experimental models.
  • There remains controversy as to the benefits of protein restriction for treatment. Although patients are advised against high-protein diets, low-protein diets are not usually recommended and the emphasis is to maintain good nutrition.