SUSS test for eating disorder examinations

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💪 SUSS test means Sit-Up, Squat, Stand test. It is a simple bedside assessment of muscle power and physical risk in patients with anorexia nervosa or severe restrictive eating disorders.

✅ What It Is Used For

• Assessing physical weakness in anorexia nervosa or restrictive eating disorders.
• Helping identify patients at higher medical risk.
• Supporting risk assessment alongside BMI, weight loss rate, observations, blood tests and ECG.
• Useful because a patient may appear well despite being medically fragile.

📋 What the Test Involves

• Sit-up: can the patient sit up from lying flat without using their hands?
• Squat: can the patient squat down?
• Stand: can the patient rise from squatting back to standing?

⚠️ Only perform the test if it is safe. Do not attempt it if the patient is dizzy, very frail, medically unstable, at high falls risk or unable to cooperate safely.

🔢 Simple Interpretation

• Normal strength: able to sit up, squat and stand without difficulty.
• Mild weakness: needs effort or uses hands for support.
• Marked weakness: unable to rise from squat or sit up without help.
• Severe weakness: suggests high physical risk and need for urgent medical review.

🚩 Why It Matters

• Muscle weakness may reflect severe malnutrition.
• Respiratory and cardiac muscle weakness can occur in advanced starvation.
• Traditional early warning scores may look falsely reassuring in anorexia nervosa.
• Bradycardia, hypotension and hypothermia may be signs of starvation rather than “normal fitness”.

🩺 Assess Alongside

• BMI and percentage median BMI in children/adolescents.
• Rate of weight loss, especially rapid recent loss.
• Pulse, blood pressure, postural blood pressure and temperature.
• Hydration status and peripheral circulation.
• Blood tests: U&Es, glucose, phosphate, magnesium, calcium, LFTs, FBC and CK if indicated.
• ECG, especially QTc interval, bradycardia or electrolyte disturbance.
• Purging behaviours, laxatives, diuretics, vomiting or insulin omission.
• Suicide risk, self-harm, safeguarding and capacity.

🚑 Red Flags Requiring Urgent Escalation

• Unable to sit up or stand safely.
• Syncope, collapse or severe postural dizziness.
• Marked bradycardia, hypotension or hypothermia.
• Electrolyte disturbance, especially hypokalaemia or hypophosphataemia.
• Chest pain, palpitations, prolonged QTc or arrhythmia.
• Severe dehydration or acute kidney injury.
• Rapid weight loss or very low BMI.
• Suicidal thoughts, severe self-neglect or safeguarding concerns.

🏥 Management Principles

• Use SUSS as part of a broader eating disorder physical risk assessment.
• If abnormal, consider urgent medical assessment and eating disorder specialist input.
• Correct dehydration and electrolyte abnormalities carefully.
• Assess risk of refeeding syndrome before nutritional rehabilitation.
• Involve eating disorder services, paediatrics, acute medicine or psychiatry depending on age and severity.
• Consider admission if there is medical instability, severe weakness or high psychiatric risk.

🧠 Clinical Pearl

In severe anorexia nervosa, the patient may look alert and superficially well while having dangerous physiological compromise. The SUSS test is useful because proximal muscle weakness is a visible marker of malnutrition and physical risk. It should never be used in isolation: combine it with observations, ECG, electrolytes, weight trajectory, purging history and mental health risk.

📚 Exam Pearl

💪 SUSS = Sit-Up, Squat, Stand. It is used in anorexia nervosa to assess muscle power and physical risk, not to diagnose the eating disorder itself.