This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.
Why screen for malnutrition?
Malnutrition is common and often missed, especially in older adults, people with cancer or chronic disease and patients in hospital. It weakens muscles and immunity, slows wound healing, increases falls and infections and lengthens hospital stays. Screening finds people at risk early, when simple measures such as fortified food or oral supplements can still help.
The five steps of MUST
The Malnutrition Universal Screening Tool was developed in 2003 by the Malnutrition Advisory Group of BAPEN in the United Kingdom. It works in five steps:
- BMI score: over 20 scores 0; 18.5 to 20 scores 1; under 18.5 scores 2.
- Weight loss score: unplanned loss in the past 3 to 6 months under 5% scores 0; 5 to 10% scores 1; over 10% scores 2.
- Acute disease effect: 2 points if the person is acutely ill and has had, or is likely to have, no nutritional intake for more than 5 days.
- Overall risk: add the scores.
- Management: follow the care plan for that risk level.
Risk and care plan
| Score | Risk | What to do |
|---|---|---|
| 0 | low | routine care; repeat screening weekly in hospital, monthly in care homes, yearly in the community for higher-risk groups |
| 1 | medium | observe: record food and fluid intake for 3 days; act if intake is poor; repeat screening |
| 2 or more | high | treat: refer to a dietitian or nutrition team, improve intake, monitor and review the care plan |
Example
A person 5 feet 7 inches tall who weighed 138 pounds four months ago and now weighs 128 pounds has a BMI of about 20 and has lost about 7% of their weight. BMI scores 0 and weight loss scores 1: a total of 1, medium risk. Their food intake should be recorded for three days.
Practical points
- Weigh people on calibrated scales, in light clothing.
- If height cannot be measured, use recalled height, the ulna length or knee height.
- Unplanned weight loss matters more than the absolute weight: a person with obesity can still be malnourished.
- Fluid retention, edema or amputation can hide weight changes.
Limits
MUST is a screening tool, not a diagnosis. A full nutritional assessment looks at diet, muscle mass, function and the underlying disease. Other tools exist for specific groups, such as the Mini Nutritional Assessment for older adults and the NRS-2002 for hospital patients.