IM10.9-11 | Renal Failure Clinical Evaluation — Summary & Reflection

KEY TAKEAWAYS

Clinical evaluation of renal failure is structured around three goals: determine acuity (AKI vs CKD vs AKI-on-CKD), determine aetiology category (pre-renal/intrinsic/post-renal), and assess severity and complications.

History domains: Onset/duration (chronic symptoms = nocturia, fatigue, pruritus for months); Category clues (fluid loss for pre-renal; nephrotoxin for intrinsic; LUTS for post-renal); Nephrotoxin screen (NSAIDs, aminoglycosides, contrast, herbal); Systemic disease (diabetes, HTN, lupus, vasculitis, malignancy); Uraemic symptoms (nausea, oliguria, confusion, pruritus, pericardial pain).

Examination domains: Volume status (depletion = dry mouth, postural hypotension, flat JVP; overload = elevated JVP, oedema, crepitations); Uraemic signs (asterixis, pericardial rub, Kussmaul breathing, uraemic frost, pallor); Systemic causes (retinopathy for DM, malar rash for SLE, palpable kidneys for PKD, distended bladder for BPH).

Differential generation: Map clinical pattern to category; prioritise by likelihood AND treatability (obstructive AKI is immediately reversible; RPGN requires urgent biopsy; volume depletion responds to fluids within hours). Three immediate bedside decisions: fluid challenge vs restriction (based on JVP/volume status), catheterise (if distended bladder), ECG + calcium gluconate (if hyperkalaemia risk).

REFLECT

Return to the two patients from the opening hook. For Patient A (62-year-old woman with UTI, gentamicin, and oliguria): her history reveals a nephrotoxin (gentamicin) and concurrent ACE inhibitor, plus a 3-day course of an antibiotic known to cause tubular injury. Her examination shows euvolaemia — giving fluids would not help and might worsen matters. The finding of oliguria on an aminoglycoside must immediately trigger stopping the drug, measuring a drug level, and initiating daily creatinine and potassium monitoring. For Patient B (48-year-old man with bibasal crepitations, elevated JVP, and creatinine 5.8 mg/dL): his examination tells you he is severely volume-overloaded, almost certainly with CKD plus an acute decompensation. The urge to give 'renal dose' fluids must be actively resisted. His is not a volume-depleted kidney — it is a failing kidney in a volume-overloaded patient. Think about a patient you have encountered on the wards with elevated creatinine. Was a systematic volume status assessment performed? Was the JVP measured? Was the medication list reviewed for nephrotoxins? What would have changed in the management if those findings had been documented early?