Malnutrition - A Clinical Overview

Malnutrition: A Clinical Overview

Definition

Malnutrition is a state resulting from inadequate intake, impaired absorption, or increased nutritional requirements, leading to altered body composition and reduced physical and clinical function.

It includes:

• Undernutrition (energy and/or protein deficiency)
• Micronutrient deficiency (e.g. iron, B12, vitamin D)
• Disease-related malnutrition (with or without inflammation)

Malnutrition is often subclinical and multifactorial

Common indicators include:

Anthropometric / Physical

• Unintentional weight loss (>5% in 3 months or >10% in 6 months)
• Reduced muscle mass or strength (sarcopenia)
• Low BMI or significant weight change at any BMI
• Oedema (in some cases)

Functional

• Fatigue, reduced exercise tolerance
• Decline in activities of daily living
• Increased falls risk (particularly in older adults)

Clinical / Biochemical

• Recurrent infections, poor wound healing
• Iron deficiency ± anaemia
• Low vitamin D, B12, folate
• Delayed recovery from illness or surgery

Dietary / Behavioural

• Reduced appetite or early satiety
• Restrictive eating patterns
• Limited dietary variety

At-Risk Populations

• Older adults
• People with chronic disease (e.g. GI disorders, cancer, COPD)
• Individuals on restrictive diets or with eating disorders
• Post-surgical patients (especially GI surgery)
• Socially isolated individuals or those with limited food access

Contributing Factors

• Inadequate intake (intentional or unintentional)
• Increased requirements (infection, inflammation, recovery)
• Malabsorption (e.g. coeliac disease, IBD, pancreatic insufficiency)
• Medication effects (appetite suppression, nutrient depletion)
• Functional decline (reduced ability to shop, cook, or eat)

Assessment (Brief Clinical Approach)

1. Screening tools

• MUST (Malnutrition Universal Screening Tool)
• MST (Malnutrition Screening Tool)

2. Key questions

• Recent weight change?
• Appetite and intake?
• GI symptoms or dietary restrictions?
• Functional changes (strength, fatigue)?

3. Physical assessment

• Muscle wasting (temporal, clavicular, quadriceps)
• Subcutaneous fat loss
• Fluid status

4. Biochemistry (supportive, not diagnostic)

• Iron studies, B12, folate
• Vitamin D
• CRP (inflammation context)

Management Principles

• Address underlying cause (medical, social, behavioural)
• Optimise energy and protein intake
• Correct micronutrient deficiencies
• Consider oral nutrition supplements where appropriate
• Support meal structure and access
• Monitor weight, intake, and functional outcomes

Key Clinical Message

Malnutrition is not defined by body size.
It is defined by function, intake, and physiological demand.

Early identification improves:

• Recovery outcomes
• Strength and independence
• Quality of life