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IM10.1-24 | Acute Kidney Injury and Chronic Renal Failure — PBL Case

CLINICAL SETTING

The general medicine ward at a district teaching hospital in Tamil Nadu. It is 9:30 PM. Dr Kavitha, the second-year medicine resident on call, is reviewing admissions with two final-year students, Arun and Priya. The next patient to be clerked is Mr Selvam, a 62-year-old retired government clerk from a small town 80 km away, brought in by his daughter because 'his legs have been swelling for the past three months and he has not been passing urine properly for the past week.' His daughter adds: 'He has been taking painkillers for his knee pain for over a year — he gets them from the local pharmacy without a prescription.' Mr Selvam looks pale and tired. He speaks slowly. He tells Dr Kavitha: 'I have had sugar for 10 years and blood pressure for 8 years. I stopped my medicines 6 months ago because I felt fine and the medicines were expensive.' His blood pressure today is 178/108 mmHg. He is peripherally oedematous to the mid-shin. His breathing is slightly laboured. Dr Kavitha turns to the students: 'Before we touch him — what are you already thinking?'

Trigger 1: First Impressions — Building the Pre-Test Probability

Dr Kavitha completes the history. Key points: Mr Selvam stopped his antihypertensives and metformin 6 months ago. He has been taking ibuprofen 400 mg twice daily for knee osteoarthritis, purchased over the counter. He has not had any kidney function tests in the past 3 years. His urine has been frothy for 6 months. Over the past week he has passed less than 400 mL per day. He has no fever, no dysuria, no haematuria. He has mild nausea and has not been eating well. On examination: BP 178/108 mmHg, pulse 92/min regular, JVP raised at 5 cm above the sternal angle, respiratory rate 22/min, SpO2 94% on room air. Bilateral pitting oedema to mid-shin. Lung bases: fine crepitations bilaterally. Abdomen: no ascites, kidneys not ballotable, no suprapubic fullness. Neurological: mild asterixis on outstretched hands. Fundoscopy: arteriolar narrowing and AV nipping. The students write on their whiteboard: 'Working diagnosis: ???'

DISCUSSION POINTS

  • Using the history and examination findings, classify Mr Selvam's renal failure: is this AKI, CKD, or AKI-on-CKD? What specific clinical features support each possibility, and what additional information would help distinguish between them?
  • Mr Selvam has been taking ibuprofen 400 mg twice daily for over a year. Explain the mechanism by which chronic NSAID use causes renal injury — and why this risk is amplified in a patient who already has diabetic and hypertensive nephropathy.
  • The presence of frothy urine for 6 months, raised JVP, bilateral crepitations, and asterixis each represent a different pathophysiological process. Identify what each sign indicates and what it implies for the severity of his condition.
Click to reveal Trigger 2: The Investigations Return — A Picture Worse Than Expected (discuss previous trigger first!)

Trigger 2: The Investigations Return — A Picture Worse Than Expected

Blood results arrive two hours later. Serum creatinine 9.4 mg/dL, urea 186 mg/dL, Na 134 mEq/L, K 6.8 mEq/L, Cl 98 mEq/L, HCO3 9 mEq/L, Ca 7.2 mg/dL, phosphorus 7.4 mg/dL, Hb 7.4 g/dL (MCV 82 fL, normochromic). Blood sugar (fasting) 214 mg/dL. HbA1c 10.2%. Urinalysis: protein 4+, blood 1+, glucose 3+. Microscopy: waxy casts and granular casts, no red cell casts. The ECG shows: peaked T waves in V1-V4, PR interval 0.22 seconds, QRS 0.11 seconds. Renal ultrasound: both kidneys 8.5 cm bilaterally, increased echogenicity, no hydronephrosis. The nurse calls Dr Kavitha urgently: 'The ECG looks abnormal.' Dr Kavitha shows it to Arun: 'Walk me through what you see. What are you going to do in the next five minutes?'

DISCUSSION POINTS

  • Calculate the anion gap from the given values and interpret it. What does the combination of high anion gap, low bicarbonate, hyperphosphataemia, and hypocalcaemia tell you about the metabolic state of this patient's kidneys?
  • Describe the ECG findings in Mr Selvam's case in sequence from least to most dangerous. What is the immediate management of his hyperkalaemia, and in what order should each intervention be applied?
  • The renal ultrasound shows bilaterally small kidneys (8.5 cm) with increased echogenicity and no hydronephrosis. How does this finding change your interpretation of the clinical picture — is this predominantly AKI, CKD, or AKI-on-CKD? What does the urinary cast pattern tell you about the nature of the injury?
Click to reveal Trigger 3: The Dialysis Decision and Its Consequences (discuss previous trigger first!)

Trigger 3: The Dialysis Decision and Its Consequences

Dr Kavitha stabilises Mr Selvam with IV calcium gluconate, insulin-dextrose, and sodium bicarbonate. Over the next 4 hours, serum potassium falls to 5.8 mEq/L and SpO2 improves to 97% with supplemental oxygen. However, urine output over the next 12 hours is only 80 mL despite a fluid challenge. His bicarbonate has not improved above 11 mEq/L. The nephrologist is called and reviews Mr Selvam at midnight. She explains to the family that dialysis will likely be needed. She then turns to Mr Selvam and says: 'Mr Selvam, I want to explain what is happening with your kidneys and what your options are.' Mr Selvam, clearly distressed, says: 'Doctor, I am afraid. I do not want any machine. I have seen my neighbour on dialysis — he went three times a week and never had a normal life. Can you not just give me medicines?' His daughter, in tears, insists: 'Doctor, please do whatever it takes to save him. He has to start dialysis.'

DISCUSSION POINTS

  • Using the AEIOU criteria, identify which of Mr Selvam's current findings meet indications for emergency dialysis. Name all five AEIOU criteria with their specific thresholds and indicate which ones Mr Selvam satisfies.
  • The patient has expressed a preference not to start dialysis. Describe how you would approach this conversation using the principles of shared decision-making and bioethical analysis. Which ethical principle most directly supports the patient's right to refuse, and how do you balance this with the daughter's request?
  • What is conservative kidney management (CKM) and for which patients is it an evidence-based alternative to dialysis? Is Mr Selvam a candidate for CKM based on his current presentation?
Click to reveal Trigger 4: Living With the Diagnosis — Education, Diet, and the Long Road (discuss previous trigger first!)

Trigger 4: Living With the Diagnosis — Education, Diet, and the Long Road

After a prolonged conversation involving Mr Selvam, his daughter, the nephrologist, and Dr Kavitha, Mr Selvam agrees to a trial of haemodialysis for two weeks to see if his kidneys recover. He is started on haemodialysis via a temporary femoral catheter. After two sessions, his creatinine falls to 4.2 mg/dL, potassium normalises, and he begins to pass 600 mL of urine per day. The nephrologist explains: 'His kidneys have some recovery — this may be AKI-on-CKD. We may be able to wean off dialysis, but his underlying CKD is advanced and permanent.' Mr Selvam is now eating cautiously. His daughter asks the students: 'What should he eat? He has been eating his normal Tamil meals — rice, dal, bananas, buttermilk, pickles. Is any of this a problem?' Priya is asked to conduct the diet counselling session.

DISCUSSION POINTS

  • Construct a renal diet counselling plan specifically for Mr Selvam. For each dietary element — protein, potassium, phosphate, sodium, and fluids — state the specific target, identify which of his described foods is problematic, suggest an alternative, and explain the reason in plain language he can understand.
  • Mr Selvam asks: 'My blood sugar is also very high. Can I take my metformin tablet again?' Explain the pharmacological reason why metformin should be held or permanently discontinued at his current level of kidney function, and what alternative glycaemic therapies are safe in CKD.
  • Describe the comprehensive outpatient management plan for Mr Selvam if he is discharged with CKD G4 or G5. Include: BP target and antihypertensive choice, glycaemic targets in CKD, anaemia management, CKD-MBD monitoring and treatment, and nephrology follow-up plan including criteria for AV fistula referral.

Group Task Assignments

  • Using Mr Selvam's case, construct the complete minimum diagnostic panel for a patient presenting with oliguria and elevated creatinine of unknown duration. For each investigation, state the specific clinical question it answers and the threshold that would change management.
  • Design a patient information leaflet for Mr Selvam explaining his renal diagnosis, his dietary restrictions, and his follow-up requirements in Tamil Nadu dialect-appropriate simple English (assume a Class 10 reading level). The leaflet must be accurate, specific (not generic), and address his most likely questions.
  • Debate the proposition: 'Mr Selvam should have been referred to a nephrologist at the point when he first developed frothy urine six months ago.' What were the missed opportunities in the primary care pathway, and what system-level interventions could prevent late presentations of advanced CKD in rural India?
  • Develop a stepped management protocol for hyperkalaemia in a patient with renal failure, from ECG recognition through to dialysis — stating the agent, dose, mechanism, onset of action, and duration of effect for each step in a table format suitable for a ward reference card.

Learning Issues

Research these questions and bring your findings to the discussion.

  1. [IM10.2] What are the pathophysiological mechanisms by which diabetes, hypertension, and chronic NSAID use independently and synergistically cause progressive renal injury?
  2. [IM10.13] How is FENa calculated and interpreted, and in what clinical situations is it unreliable? What is the interpretation of urinary cast types in AKI and CKD?
  3. [IM10.14] Describe the sequential ECG changes in hyperkalaemia from earliest (peaked T waves) to most lethal (sine wave, VF), and outline the pharmacological management in order of administration including mechanism, dose, and onset of action for each agent.
  4. [IM10.19] What are the AEIOU indications for emergency dialysis in AKI? State each criterion with its specific clinical threshold and the physiological rationale for each indication.
  5. [IM10.20] What are the safe thresholds for prescribing metformin in CKD, and which antihypertensives and glycaemic agents are preferred and avoided at different CKD GFR stages?
  6. [IM10.23] How does the principle of patient autonomy apply when a patient with ESRD refuses dialysis against the family's wishes? What is the ethical and legal framework governing this situation under Indian law?