Inanition

Definition. Inanition is a state of profound exhaustion and wasting resulting from prolonged inadequate intake, absorption or utilisation of food — the advanced end-stage of starvation, with loss of both fat and muscle mass, weakness and multi-organ dysfunction. In geriatric practice it overlaps closely with the "failure to thrive" syndrome of the elderly.

Distinction from related states (very high yield). Inanition/starvation — pure nutrient deficiency, largely reversible with feeding. Cachexia — inflammation-driven, cytokine-mediated (TNF-α, IL-1, IL-6) loss of muscle in cancer, heart failure, COPD or CKD, not fully reversible by nutrition alone. Sarcopenia — age-related loss of muscle mass and strength. Anorexia of ageing — the physiological decline in appetite with early satiety, delayed gastric emptying and altered gut hormones.

Causes in the elderly — the "9 Ds". Dementia, Depression, Dysphagia, Dentition, Drugs, Disease (malignancy, infection, hyperthyroidism, heart failure), Diarrhoea/malabsorption, Dysgeusia and Destitution (poverty and social isolation). Also immobility, alcohol misuse, restrictive therapeutic diets, and elder abuse or neglect.

Clinical features and consequences. Severe weight loss with temporal and interosseous muscle wasting, hypothermia, bradycardia and hypotension, sarcopenia with falls and fractures, pressure ulcers, impaired cell-mediated immunity with infection, delayed wound healing, oedema from hypoalbuminaemia, apathy, depression and cognitive slowing, and greatly increased mortality and rates of institutionalisation.

Assessment. Screen with the MNA-SF (or MUST); document weight, BMI, percentage unintentional weight loss and calf circumference. Apply the GLIM criteria — at least one phenotypic criterion (weight loss, low BMI, reduced muscle mass) plus one aetiologic criterion (reduced intake or absorption, or disease burden with inflammation). Measure hand-grip strength. Investigate with haemoglobin, electrolytes, calcium, vitamin D, B , 12 thyroid function, CRP and albumin, and screen for malignancy, depression, dysphagia and oral disease. A comprehensive geriatric assessment with medication review is mandatory.

Management. Treat reversible causes first — dental repair, dysphagia therapy with texture modification and speech therapist input, treatment of depression (mirtazapine is useful where weight gain is desirable), and withdrawal of appetite-suppressing drugs (digoxin, SSRIs, metformin, opioids, anticholinergics). Then apply a "food-first" approach — food fortification, small frequent energy-dense meals, protein 1.2–1.5 g/kg/day, feeding assistance, improved mealtime environment and social eating; add oral nutritional supplements between (not with) meals. Combine with resistance exercise to convert intake into muscle, correct vitamin D and micronutrient deficiency, and consider tube feeding only after explicit goal-setting — it should be avoided in advanced dementia.

Two changes that reverse older teaching. First, megestrol acetate and other appetite stimulants are now to be avoided in older adults (AGS Beers Criteria 2023) — they produce minimal weight gain with no benefit on function or survival, and carry risks of thrombosis, adrenal suppression, fluid retention and death. Second, under the GLIM framework and current ESPEN geriatric guidance, serum albumin is no longer accepted as a nutritional marker and has been reclassified as an inflammatory marker; the diagnosis of malnutrition must be made on phenotypic and aetiologic criteria with objective assessment of muscle mass.