Uraemic Syndrome and Complications
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Direct answer
Uraemic syndrome is the cluster of clinical features that develops when retained solutes and failed renal endocrine functions accumulate in advanced chronic kidney disease, usually below an eGFR of about 15 mL/min per 1.73 m². Its key complications are pericarditis, platelet dysfunction with bleeding, uraemic neuropathy, encephalopathy and refractory pruritus. Dialysis is indicated when these features are severe or fail to respond to conservative care.
What you must remember
- Onset threshold: symptoms usually appear in advanced chronic kidney disease, with an eGFR commonly below about 15 mL/min per 1.73 m², though timing varies with diet, volume status and comorbidity.
- Uraemic pericarditis: a fibrinous pericarditis with a friction rub, a classic dialysis indication, and effusion can progress to tamponade.
- Platelet dysfunction: prolonged bleeding time with a normal platelet count, caused by uraemic toxins that impair platelet adhesion and activation, compounded by anaemia.
- Uraemic encephalopathy: confusion, drowsiness, myoclonus and asterixis, progressing to seizures or coma in severe cases.
- Uraemic neuropathy: a symmetrical, length-dependent sensorimotor neuropathy with burning feet, restless legs and reduced distal sensation.
- Uraemic pruritus: generalised itching, often worse at night, linked to phosphate, parathyroid hormone and opioid-system imbalance.
- Gastrointestinal features: anorexia, nausea, vomiting, metallic taste and uraemic fetor, with a risk of gut bleeding.
- Endocrine and haematological defects: anaemia from erythropoietin deficiency, secondary hyperparathyroidism and impaired vitamin D activation.
A bedside approach to the uraemic patient
A 58-year-old man with diabetic nephropathy is referred with a creatinine of 9.2 mg/dL, confusion, itching and a rub over the precordium. The aim is to find which uraemic features are present, because they decide the timing of dialysis.
- Check the AEIOU list: Look for acidosis, refractory hyperkalaemia, intoxication, fluid overload and uraemic features before choosing conservative care.
- Examine the pericardium: A friction rub with a raised JVP or muffled heart sounds suggests effusion, and echocardiography confirms it.
- Test the bleeding: Gum or gut bleeding with a normal platelet count points to uraemic platelet dysfunction, so haemoglobin and bleeding history are reviewed.
- Assess the nervous system: Asterixis and confusion indicate encephalopathy, while glove-and-stocking sensory loss with burning feet indicates neuropathy.
- Treat the itch at source: Correct phosphate and parathyroid excess, check dialysis adequacy, and consider UV-B phototherapy or a gabapentinoid when these fail.
- Plan dialysis by features: Start when any AEIOU feature is present, rather than on a creatinine value alone.
The unifying principle is that dialysis treats most uraemic features at their source. A severe feature therefore changes the timing of dialysis rather than prompting a symptomatic fix alone.
Where the examiner tries to catch you
Most uraemia questions hinge on naming the feature correctly and linking it to the right indication.
- Trap: treating a uraemic pericardial effusion with NSAIDs alone. Correct: NSAIDs are avoided in chronic kidney disease, and intensified dialysis is the preferred step, with urgent drainage if tamponade develops.
- Trap: correcting uraemic bleeding by transfusing platelets. Correct: the platelet count is normal, so the defect is functional, and the usual options are dialysis, anaemia correction, desmopressin or conjugated oestrogens.
- Trap: deciding on dialysis from creatinine alone. Correct: the AEIOU features drive timing, and a patient can be stable at a high creatinine with good symptom control.
Frequently asked questions
Which uraemic complication is the classic indication for urgent dialysis?
Uraemic pericarditis is a classic indication for urgent dialysis, and a pericardial effusion with tamponade needs immediate drainage alongside intensified dialysis. Uraemic encephalopathy is the other urgent feature, presenting with asterixis, myoclonus and confusion.
Why does uraemia cause bleeding with a normal platelet count?
Uraemic toxins impair platelet adhesion and activation, so the platelets are present but dysfunctional, producing a prolonged bleeding time. Anaemia adds to the risk, and the bleeding tendency responds to dialysis, correction of anaemia and desmopressin.
What is uraemic pruritus and how is it treated?
Uraemic pruritus is generalised itching in chronic kidney disease, often worse at night, linked to phosphate, parathyroid hormone and opioid-system imbalance. Treatment corrects phosphate and parathyroid excess, optimises dialysis, and uses UV-B phototherapy or gabapentinoids when these measures fail.
Which neuropathy is typical of uraemia?
Uraemic neuropathy is a symmetrical, length-dependent sensorimotor neuropathy causing burning feet, restless legs and reduced distal sensation. It is distinct from dialysis disequilibrium syndrome, and its symptoms may improve with adequate dialysis.
What does the AEIOU mnemonic mean for dialysis?
AEIOU lists the standard indications for urgent dialysis: acidosis, refractory electrolyte disturbance such as hyperkalaemia, intoxication with dialysable drugs, fluid overload, and uraemic features such as pericarditis or encephalopathy. A patient with any one of these features needs dialysis regardless of the creatinine value.