Malnutrition

🧭 When to suspect

Malnutrition (undernutrition) is a state in which a deficiency of energy, protein and micronutrients produces measurable adverse effects on body composition, on physical and mental function, and on clinical outcome. It is common, under-recognised, and overwhelmingly a community problem – around 93% of those affected live in their own homes, not in hospital. It is both a cause and a consequence of illness, and it drives infection, poor wound healing, falls, frailty and delayed recovery.

Suspect it in any adult with a low weight, unintentional weight loss, or reduced intake, and screen actively rather than waiting for it to declare itself. The strongest pointers are a Body Mass Index (BMI) below 18.5 kg/m², unintentional weight loss of more than 10% over 3–6 months, or a BMI below 20 kg/m² with unintentional weight loss of more than 5% over the same period.

Be especially vigilant in the frail elderly and in those with chronic disease (cancer, Chronic Obstructive Pulmonary Disease (COPD), heart failure, chronic kidney disease, inflammatory bowel disease, dementia, or neurological conditions causing dysphagia), recent illness or hospital admission, alcohol dependence, or adverse social circumstances. The structured tool used across UK primary care is the Malnutrition Universal Screening Tool (MUST), which combines three components into a single risk score.

Add the three scores: 0 = low risk, 1 = medium risk, 2 or more = high risk. The total drives the management plan (see Management). Screen at registration, opportunistically (health checks, vaccinations), on admission to a new care setting, and whenever there is clinical concern; repeat at least annually in the community, and more often in higher-risk groups.

Source: NICE CG32 · BAPEN