Failure to Thrive in Adults: Diagnostic Components
Failure to thrive in adults is a clinical syndrome characterized by insufficient weight gain, weight loss, decreased appetite, poor nutrition, and functional decline, typically occurring in the context of multiple concurrent chronic diseases and impairments. 1, 2
Core Diagnostic Features
The diagnosis encompasses four key syndromes that are individually predictive of adverse outcomes and frequently coexist 2, 3:
- Impaired physical functioning - decline in activities of daily living and self-care abilities beyond normal age-related changes 2, 4
- Malnutrition - weight loss, decreased appetite, and poor nutritional status 3, 5
- Depression - loss of interest in social activities, social withdrawal, and mood disturbances 2, 6
- Cognitive impairment - decline in mental function, which may include dementia or delirium 3, 4
Clinical Presentation
Adult failure to thrive manifests as an insidious deterioration across multiple domains 5, 6:
- Weight loss and nutritional decline - progressive loss of body mass and decreased subcutaneous fat 3, 5
- Functional deterioration - gradual decline in physical abilities and increased dependency on caregivers 2, 6
- Inactivity and social withdrawal - reduced engagement in previously enjoyed activities 3, 6
- Lack of obvious single explanation - the condition results from combined effects rather than one identifiable cause 5
Important Diagnostic Considerations
A critical pitfall is that "failure to thrive" can reinforce fatalism and intellectual laziness rather than prompting systematic evaluation of each contributing syndrome. 2 The term has had its own ICD-9 code since 1979, but this can create barriers to proper evaluation by suggesting a unified diagnosis when actually multiple concurrent problems require individual assessment 2.
The differential diagnosis is complex because each of the four core syndromes can contribute to the others - for example, depression can cause malnutrition, which worsens physical function, which may worsen cognitive impairment 2, 3. Depression is particularly important to identify early, as failure to diagnose depression (rather than failure to diagnose "FTT") is often the actual clinical problem leading to delayed treatment 6.
Essential Evaluation Components
Initial assessment must systematically address 3, 4:
- Physical and psychological health status - including chronic disease burden and medication review to identify drug side effects or interactions 3
- Functional ability assessment - specific evaluation of activities of daily living and self-care capacity 2, 4
- Nutritional status - documentation of weight trajectory, appetite, and dietary intake 3, 5
- Socioenvironmental factors - social isolation, caregiver availability, and living situation 3, 5
- Cognitive function and mood - formal screening for dementia, delirium, and depression 3, 4
The most common etiologies are dementia, depression, delirium, drug reactions, and chronic diseases - these should be the primary focus of diagnostic efforts 4.