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

• Delayed recovery

Suspect it in any adult with:

• A low weight

• Unintentional weight loss

• Reduced intake

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

• 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

• 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

• Whenever there is clinical concern

Repeat at least annually in the community, and more often in higher-risk groups.

Source: NICE CG32 · BAPEN