Hypokalaemia OSCE history checklist

1. Opening and communication

• Wash hands, introduce yourself, confirm patient identity.
• Explain: “I’d like to ask some questions about your low potassium level and possible causes. Is that okay?”
• Check comfort, offer a chaperone if appropriate.
• Clarify why potassium was tested and whether they have been told the result.

2. Presenting complaint

• “What symptoms brought you to hospital or your doctor?”
• “When did they start?”
• “Did they begin suddenly or gradually?”
• “Are they getting worse?”

3. Screen immediately for severe symptoms and complications

• Palpitations, skipped beats, racing heartbeat
• Chest pain
• Dizziness, presyncope or syncope
• Shortness of breath

• Muscle weakness, cramps, aches or twitching
• Difficulty standing, walking, climbing stairs, or lifting arms
• Tingling or numbness
• Difficulty swallowing, speaking, or breathing
• Episodes of paralysis, especially sudden attacks

• Constipation
• Abdominal distension or pain
• Nausea and vomiting
• Reduced urine output, excessive urination, or thirst

4. Explore potassium losses

Gastrointestinal loss

• Vomiting, diarrhoea, how frequent and for how long?
• Recent gastroenteritis, food poisoning, travel, antibiotics, or laxative use?
• Chronic diarrhoea, inflammatory bowel disease, coeliac disease, or bowel surgery?
• Excessive sweating or heavy exercise?
• Poor oral intake, fasting, malnutrition, or alcohol excess?
• Ask sensitively about self-induced vomiting, laxative misuse, eating disorder symptoms, and weight concerns.

Renal loss

• Passing large volumes of urine, nocturia, thirst?
• History of kidney disease or kidney stones?
• Recurrent vomiting with alkaline urine, or known renal tubular disorder?
• Previous low potassium episodes?
• Symptoms of high blood pressure such as headaches or visual disturbance.

5. Medication and substance history

• “Do you take water tablets or diuretics?”
  Examples: furosemide, bumetanide, thiazides.
• Laxatives, enemas, bowel preparations?
• Insulin or recent glucose infusion?
• Salbutamol or other beta-2 agonist inhalers or nebulisers?
• Steroids, amphotericin, certain antibiotics, or high-dose penicillins?
• Digoxin, as hypokalaemia raises digoxin toxicity risk.
• Liquorice products, herbal remedies, or supplements?
• Recent treatment for diabetic ketoacidosis or refeeding after malnutrition?

6. Ask about redistribution of potassium into cells

• Recent insulin use or treatment for high blood glucose?
• Salbutamol nebulisers or frequent inhaler use?
• Panic attacks or hyperventilation?
• Recent refeeding after starvation or prolonged poor intake?
• Symptoms of hyperthyroidism: weight loss, tremor, heat intolerance, sweating, diarrhoea, anxiety, neck swelling?
• Previous episodic weakness with a family history of similar episodes?

7. Relevant past medical history

• Hypertension, especially difficult-to-control or early-onset hypertension
• Heart disease, arrhythmia, heart failure, previous myocardial infarction
• Kidney disease or dialysis
• Liver disease or cirrhosis
• Diabetes mellitus
• Thyroid disease
• Adrenal disease, Cushing syndrome, or Conn syndrome
• Chronic respiratory disease requiring frequent beta-agonists
• Eating disorders or chronic alcohol use
• Previous similar episodes and prior potassium or magnesium replacement

8. Family history

• Family history of low potassium, periodic paralysis, kidney disease, early hypertension, endocrine disease, or sudden cardiac death.

9. Social history

• Diet: poor intake, restrictive diet, food insecurity.
• Alcohol intake.
• Smoking and recreational drugs.
• Occupation and heavy physical exertion.
• Recent travel or infective contacts if diarrhoea is present.
• Impact on daily activities, mobility, and support at home.

10. Systems review

• Fever, weight loss, night sweats
• Polyuria, polydipsia
• Symptoms of magnesium deficiency or malnutrition
• Features of endocrine disease:
  • Cushing syndrome: weight gain, bruising, proximal weakness
  • Hyperaldosteronism: hypertension, headaches, muscle weakness
  • Hyperthyroidism: tremor, palpitations, heat intolerance

11. Summarise and close

“You have had [duration] of [symptoms], with possible potassium loss or shift related to [likely cause]. I am particularly concerned about [red flags if present].”

• “I would check your observations, hydration status, muscle power and reflexes, and perform a cardiovascular examination.”
• “I would arrange an ECG and repeat serum potassium, including magnesium, renal function, glucose and acid-base assessment.”
• “If the potassium is severely low, symptoms are significant, or there are ECG changes, this needs urgent monitored replacement and treatment of the cause.”

OSCE examiner prompts: key differentials

1. Reduced intake: malnutrition, alcohol excess, eating disorder.
2. Gastrointestinal loss: vomiting, diarrhoea, laxatives, fistula or stoma.
3. Renal loss: diuretics, mineralocorticoid excess, renal tubular disorders, magnesium deficiency.
4. Intracellular shift: insulin, beta-2 agonists, alkalosis, thyrotoxic periodic paralysis, refeeding.

Hypokalaemia OSCE History Checklist

1. Start

• ☐ Introduce yourself, confirm identity, explain purpose, gain consent.
• ☐ Ask what led to the blood test or admission.
• ☐ Establish onset, duration, progression and previous episodes of low potassium.

2. Screen for urgent symptoms

Cardiac

• ☐ Palpitations or irregular heartbeat
• ☐ Chest pain
• ☐ Dizziness, collapse, presyncope or syncope
• ☐ Breathlessness

Neuromuscular

• ☐ Weakness, cramps, muscle aches or twitching
• ☐ Difficulty walking, climbing stairs, lifting arms
• ☐ Paraesthesia
• ☐ Severe weakness or paralysis
• ☐ Dysphagia or breathing difficulty

Gastrointestinal / urinary

• ☐ Constipation, abdominal distension, abdominal pain
• ☐ Nausea or vomiting
• ☐ Polyuria, polydipsia or nocturia

Red flags: syncope, palpitations, chest pain, significant weakness/paralysis, or respiratory symptoms. State that you would obtain urgent observations, ECG and senior help.

3. Identify potassium loss

Gastrointestinal losses

• ☐ Vomiting: duration, frequency, self-induced?
• ☐ Diarrhoea: acute or chronic, blood/mucus, travel, antibiotics?
• ☐ Laxative, enema, bowel-preparation or stoma losses?
• ☐ Poor intake, fasting, malnutrition, alcohol excess?
• ☐ Eating-disorder symptoms or weight-loss behaviours, asked sensitively.

Renal losses

• ☐ Diuretic use, including dose changes?
• ☐ Polyuria or kidney disease?
• ☐ Diabetes or poorly controlled hyperglycaemia?
• ☐ Previous renal tubular disorder or recurrent kidney stones?
• ☐ Hypertension, especially difficult to control or early onset?

4. Medication and substance history

• ☐ Loop or thiazide diuretics
• ☐ Laxatives
• ☐ Insulin or recent glucose infusion
• ☐ Salbutamol / frequent beta-2 agonist nebulisers
• ☐ Corticosteroids
• ☐ Amphotericin or nephrotoxic drugs
• ☐ Digoxin: ask specifically because hypokalaemia increases toxicity risk
• ☐ Liquorice, herbal remedies, supplements, recreational drugs
• ☐ Recent refeeding or treatment for DKA

5. Ask about intracellular shift

• ☐ Recent insulin, salbutamol or adrenaline exposure
• ☐ Hyperventilation or alkalosis
• ☐ Refeeding following prolonged poor intake
• ☐ Hyperthyroid symptoms: tremor, weight loss, heat intolerance, diarrhoea, palpitations
• ☐ Episodic weakness or family history of periodic paralysis

6. Past, family and social history

• ☐ Cardiac disease, arrhythmia, heart failure, ischaemic heart disease
• ☐ Kidney disease, liver disease/cirrhosis, diabetes
• ☐ Thyroid, adrenal or endocrine disease
• ☐ Previous hypokalaemia or magnesium deficiency
• ☐ Family history: periodic paralysis, renal disease, hypertension, sudden cardiac death
• ☐ Diet, alcohol, smoking, occupation, exercise and functional impact

7. Summarise and close

• ☐ Summarise likely cause: reduced intake, GI loss, renal loss, or intracellular shift.
• ☐ Ask if the patient has questions or concerns.
• ☐ State next steps:
  • Observations and hydration assessment
  • Cardiovascular and neurological examination
  • ECG
  • Repeat K⁺, U&E/renal function, magnesium, glucose and acid-base assessment
  • Urine potassium if cause remains unclear
  • Treat underlying cause and replace potassium with appropriate monitoring

“I am concerned about possible hypokalaemia-related cardiac and neuromuscular complications. I would assess the patient urgently with an ECG and repeat blood tests, correct any magnesium deficiency, replace potassium as appropriate, and address the underlying cause.”

Hypokalaemia OSCE Marking Scheme

Global rating: 0-5 marks

Critical safety items

• Ask about palpitations, syncope, chest pain or severe weakness/paralysis.
• Ask about common causes, especially vomiting, diarrhoea and diuretic use.
• Recognise the need for an ECG in severe or symptomatic hypokalaemia.
• Identify digoxin and underlying cardiac disease as increased arrhythmia-risk contexts.