History Taking · Foundation · Nephrology

Confusion and Abnormal Bloods in a 72-Year-Old Man

Practise this PLAB 2 history taking station on Chronic Kidney Disease. 8-minute voice AI simulation with feedback on all 3 marking domains.

Clinical scenario

You are an FY2 doctor in a medical admissions unit. Mr Rowan Gardiner, a 72-year-old man, has been referred by his GP with confusion, lethargy, and abnormal blood results including high urea and low sodium. Please take a focused history to determine the underlying cause, assess for signs of chronic kidney disease and hyponatraemia, and discuss your initial management plan.

Background notes: PMH: Hypertension, CKD, T2DM, Hypercholesterolaemia, Angina, BPH (prostate)

What this station tests

  • Distinguishing metabolic encephalopathy from stroke and dementia: gradual onset over weeks with abnormal renal bloods points to metabolic cause
  • Using collateral history: the patient is confused, so the wife provides the timeline and symptom progression
  • Medication review in acute kidney injury: holding nephrotoxic drugs (ACE inhibitors, diuretics, metformin) is the immediate intervention
  • Assessing fluid status: dehydrated versus overloaded determines whether to give or restrict fluids
  • Considering post-renal obstruction: BPH can cause urinary retention contributing to renal deterioration

How to use your 8 minutes

  • 0-1 min — Introduction: Introduce yourself, confirm identity, open question. 'What's brought you in today?'
  • 1-4 min — Systematic History: Presenting complaint detail (SOCRATES for pain, timeline, severity). Systems review. PMH, medications, allergies.
  • 4-6 min — Context and ICE: Social history (smoking, alcohol, occupation, living situation). Family history. Ideas, Concerns, Expectations.
  • 6-7 min — Summary and Plan: Summarise findings back to patient. Share differential/working diagnosis. Outline investigation and management plan.
  • 7-8 min — Closing: Safety netting with specific red flags. Arrange follow-up. Check for questions.

Consultation approach

The opening

Confusion in an elderly patient with abnormal renal bloods requires the candidate to identify metabolic encephalopathy rather than defaulting to stroke or dementia. The gradual onset over weeks, combined with uraemia and hyponatraemia, points to a renal cause. Mr Gardiner is 72, admitted with confusion and lethargy developing over 2 to 3 weeks. His GP found high urea and low sodium. Open with: 'Mr Gardiner, I know you are not feeling yourself. I am going to ask you some questions and also speak to your wife to understand what has been happening.' Involve the collateral historian early.

Core approach

Establish the timeline through collateral history from his wife. Gradual onset over 2 to 3 weeks: initially tired, then forgetful, then irritable, then overtly confused. Sleeping 10 to 12 hours. This gradual progression distinguishes metabolic encephalopathy from stroke (sudden) and suggests delirium rather than dementia (which develops over months to years).

Identify the renal cause. He has known CKD and is on multiple medications including ACE inhibitors, diuretics, and diabetic medications. Ask about recent changes: new medications, dose increases, intercurrent illness (infection, diarrhoea, vomiting causing dehydration), reduced oral intake. Any of these can precipitate acute-on-chronic kidney injury. Check for uraemic symptoms: nausea, anorexia, metallic taste, pruritus, hiccups. Check for hyponatraemia symptoms: headache, nausea, confusion (which overlap with uraemia).

Assess fluid status. Is he dehydrated (dry mucous membranes, reduced skin turgor, postural hypotension) or fluid overloaded (peripheral oedema, raised JVP, breathlessness)? This determines whether he needs fluid replacement or fluid restriction. Check urine output: reduced output suggests pre-renal or intrinsic renal failure.

His BPH is relevant: could urinary retention (post-renal obstruction) be contributing? Ask about urinary symptoms. ICE: he worries about stroke or dementia. His wife is frightened.

Closing and safety netting

Explain the likely cause: 'Mr Gardiner, the confusion is most likely caused by a build-up of waste products in your blood because your kidneys are not working as well as usual. This is treatable.' Address the dementia fear directly: 'This is not dementia. When we correct the kidney problem, the confusion should improve.'

Investigations: U&E, calcium, phosphate, bicarbonate, FBC, glucose, urinalysis, renal ultrasound (exclude obstruction from BPH). Medication review: hold nephrotoxic drugs (ACE inhibitor, diuretic, metformin if on it) until renal function improves. IV fluids if dehydrated. Monitor urine output.

Safety net: he is admitted, so monitoring is in-built. Explain to his wife: 'We expect the confusion to improve over the next few days as we correct the blood chemistry.' Follow-up with renal team.

How examiners mark this station

Examiners will focus on the thoroughness and structure of your history taking for chronic kidney disease. Domain 1 (Data Gathering) carries the most weight: expect marks for systematic coverage of presenting complaint, red flags, PMH, medications, social and family history. Domain 2 (Clinical Management) requires a clear differential, appropriate investigations, and a safe management plan with safety netting. Domain 3 (Interpersonal Skills) is assessed throughout: genuine exploration of ICE, active listening, empathic responses, and clear communication without jargon.

Domain 1: Data Gathering, Technical and Assessment Skills (Primary focus)

Scores well: Collateral history from wife. Gradual timeline established. Uraemic symptoms screened. Medication review. Fluid status assessed. Urine output checked. BPH and retention considered. Precipitant identified.

Costs marks: Not using collateral history. Not checking medications. Not assessing fluid status. Not considering retention.

Domain 2: Clinical Management Skills (Primary focus)

Scores well: Nephrotoxic drugs held. Fluid management based on assessment. Renal USS arranged. Electrolyte correction planned. Monitoring plan. Renal team referral. Dementia concern addressed.

Costs marks: Continuing nephrotoxic drugs. Wrong fluid management. No imaging. No renal referral.

Domain 3: Interpersonal Skills (Throughout)

Scores well: Addressing dementia fear directly (reversible with treatment). Reassuring wife about expected improvement. Communicating with confused patient respectfully. Involving wife as partner.

Costs marks: Not addressing dementia fear. Ignoring the wife. Speaking about the patient rather than to him.

Common examiner feedback (and how to fix it)

Did not gather sufficient information to make an adequate assessment of the patient's condition

Fix: Use a consistent framework for every history. After covering the presenting complaint, systematically move through PMH, drug history, social history, family history, and ICE. Keep a mental checklist.

Did not identify the patient's problems and/or did not develop a management plan adequately

Fix: Reserve the final 2 minutes to summarise your findings, share your working diagnosis with the patient, and outline your investigation and management plan including safety netting.

Common mistakes in this station

  1. Assuming the confusion is stroke or dementia without checking the bloods. A 72-year-old with gradual confusion and abnormal renal function has metabolic encephalopathy. Candidates who investigate for stroke (CT head) without addressing the renal cause miss the diagnosis.
  2. Not holding nephrotoxic medications. ACE inhibitors and diuretics worsen renal function in the context of dehydration or acute kidney injury. Candidates who do not review and hold these medications miss the most important immediate intervention.
  3. Not considering urinary retention from BPH. Post-renal obstruction is a reversible cause of renal impairment. Candidates who do not ask about urinary symptoms or arrange renal ultrasound miss a treatable cause.

Resitting PLAB 2?

If you have previously struggled with history taking stations, focus on building a consistent systematic framework that you apply to every case. Practise structuring your history into clear phases (presenting complaint, systems review, PMH, social, ICE) so that even under pressure, you cover all domains. Many resitters lose marks not on knowledge but on organisation and time management.

Example opening

Good morning/afternoon, my name is Dr [Name], I'm one of the doctors here today. Could I confirm your name and date of birth please? Thank you. So, what's brought you in to see me today?

Frequently asked questions

How should I structure the chronic kidney disease history in this PLAB 2 station?

Confusion in an elderly patient with abnormal renal bloods requires the candidate to identify metabolic encephalopathy rather than defaulting to stroke or dementia. The gradual onset over weeks, combined with uraemia and hyponatraemia, points to a renal cause. Mr Gardiner is 72, admitted with confusion and lethargy developing over 2 to 3 weeks.

What are examiners marking in this chronic kidney disease station?

Marks are won for: Collateral history from wife. Gradual timeline established. Uraemic symptoms screened. Medication review. Fluid status assessed. Urine output checked. Marks are lost for: Not using collateral history. Not checking medications. Not assessing fluid status. Not considering retention.

What is the most common mistake candidates make in this chronic kidney disease station?

Assuming the confusion is stroke or dementia without checking the bloods. A 72-year-old with gradual confusion and abnormal renal function has metabolic encephalopathy. Candidates who investigate for stroke (CT head) without addressing the renal cause miss the diagnosis.

How do I prepare for this station if I have not managed chronic kidney disease in clinical practice?

Structure beats experience here. Focus on using collateral history: the patient is confused, so the wife provides the timeline and symptom progression. Work through the consultation approach above, then rehearse it aloud under the 8-minute time pressure so the structure holds up in the exam.

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