Malnutrition is surprisingly common in hospitals, care homes and the community, and not only in low-income settings. Studies in many countries suggest that a significant proportion of adults admitted to hospital are malnourished or at risk. Malnutrition slows wound healing, increases infections and pressure ulcers, weakens muscles (including breathing muscles), and lengthens hospital stays. Yet it is often missed because patients “don’t look thin”.
The Malnutrition Universal Screening Tool (MUST), developed by the British Association for Parenteral and Enteral Nutrition (BAPEN), is a simple, validated way for nurses to identify adults at risk. Even if your workplace uses a different tool, the principles are the same.
The five steps of MUST
Step 1: BMI score
Measure height and weight and calculate body mass index (BMI = weight in kg ÷ height in m²).
- BMI more than 20 (more than 30 is obese): score 0
- BMI 18.5 to 20: score 1
- BMI less than 18.5: score 2
If you can’t measure height or weight, MUST provides alternatives: recalled or documented height and weight, ulna length to estimate height, or mid-upper arm circumference (MUAC) to estimate BMI category. If none are possible, use subjective criteria (for example, the patient looks thin, clothes are loose).
Step 2: Weight loss score
Calculate unplanned weight loss in the past 3 to 6 months:
- Less than 5%: score 0
- 5 to 10%: score 1
- More than 10%: score 2
Percentage weight loss = (previous weight − current weight) ÷ previous weight × 100.
Step 3: Acute disease effect score
If the patient is acutely ill and has had, or is likely to have, no nutritional intake for more than 5 days: score 2. This is mostly relevant in hospital, for example with critical illness, swallowing problems after stroke or major gut surgery.
Step 4: Overall risk
Add the scores from steps 1, 2 and 3:
- 0 = low risk
- 1 = medium risk
- 2 or more = high risk
Step 5: Management
- Low risk (0): routine clinical care. Repeat screening weekly in hospital, monthly in care homes, annually in the community for specific groups (for example people over 75).
- Medium risk (1): observe. Document dietary intake for 3 days (food charts). If intake improves or is adequate, repeat screening. If not, follow local policy, which may include food fortification, snacks and oral supplements, and dietitian referral.
- High risk (2 or more): treat. Refer to a dietitian or nutrition support team, or follow local policy. Set goals, improve overall intake (food first, then oral nutritional supplements as prescribed), and monitor and review the care plan.
For all categories, treat the underlying condition, provide help with eating, record malnutrition risk and needs for special diets, and follow local policy.
Worked example
Mrs A is 78 and was admitted with pneumonia. She weighs 48 kg and is 1.60 m tall. Her daughter says she weighed about 54 kg three months ago. She has barely eaten for the past 4 days and is expected to start eating again with antibiotics.
- BMI: 48 ÷ (1.60 × 1.60) = 48 ÷ 2.56 = 18.75. That is 18.5 to 20, so score 1.
- Weight loss: (54 − 48) ÷ 54 × 100 = 11.1%. That’s more than 10%, so score 2.
- Acute disease effect: she’s ill, but intake hasn’t been absent for more than 5 days and is expected to resume, so score 0.
- Total MUST: 3 = high risk.
Action: refer to the dietitian, start a food chart, offer fortified foods and snacks, request oral nutritional supplements as per policy, assist with meals, check for refeeding risk, weigh weekly, and review her care plan regularly.
Practical tips for accurate screening
- Weigh, don’t guess. Visual estimates of weight are often wrong. Use calibrated scales, ideally at the same time of day and in similar clothing.
- Ask about weight loss. “Have your clothes or rings become loose? Has anyone said you look thinner?”
- Watch for fluid. Oedema or ascites can mask weight loss; plaster casts and amputations also affect weight. Use clinical judgement and document.
- Obesity doesn’t exclude malnutrition. An obese patient who has lost a lot of weight quickly may still be malnourished.
- Screen on admission and repeat as policy states. A patient’s risk can change quickly.
- Act on the result. A high score with no action is a common audit finding.
Practical ways nurses can improve intake
- Protected mealtimes: avoid non-urgent tasks and ward rounds during meals.
- Red tray or red jug systems to flag patients who need help.
- Help with eating: open packets, cut food, sit the patient upright, ensure dentures and glasses are in place.
- Food first: fortified meals, nourishing snacks and drinks between meals.
- Respect preferences: cultural and religious diets, and familiar foods brought by family where safe.
- Treat symptoms that reduce appetite: nausea, pain, constipation, mouth ulcers, depression.
- Accurate food charts: record what was actually eaten, not what was served.
Beyond MUST
MUST is for adults. Different tools are used for children (such as STAMP or PYMS) and in some settings the Mini Nutritional Assessment (MNA) for older people. In community programmes for children in Africa and Asia, mid-upper arm circumference (MUAC) tapes are widely used to detect acute malnutrition. Whatever the tool, the principle is the same: screen everyone, identify risk early and act.