Nutrition Assessment, Anthropometry, and Clinical Diagnosis
What this domain tests
This domain tests structured nutrition assessment, anthropometric interpretation, malnutrition diagnosis, and the limits of biochemical markers.
Core rules
- Use the ABCD framework: anthropometry, biochemical data, clinical findings, and dietary intake.
- Weight change percent = (usual weight − current weight) ÷ usual weight × 100. Loss over 5% in one month or over 10% in six months is clinically significant.
- BMI under 18.5 is underweight. Asian cutoffs for overweight and obesity are 23 and 27.5. South Asian waist thresholds are about 90 cm in men and 80 cm in women.
- GLIM requires at least one phenotypic criterion (weight loss, low BMI, low muscle mass) and one etiologic criterion (reduced intake, inflammation). It grades severity, not just presence.
- Screening tools include MUST, NRS-2002, and MNA. A screening tool is not a diagnostic tool.
- Albumin and prealbumin are acute-phase reactants and not reliable nutritional status markers.
- Dietary assessment methods: 24-hour recall, food frequency questionnaire, weighed food record. Each has different recall bias and portion-size error.
Worked example
A patient whose usual weight was 70 kg now weighs 64.4 kg after three months, with BMI 19 and CRP 12 mg/L. Weight loss = 5.6 ÷ 70 × 100 = 8%. GLIM: 5–10% weight loss is a phenotypic criterion; inflammation is etiologic. The diagnosis is malnutrition, moderate by the weight-loss criterion. The CRP supports inflammation but does not replace the phenotypic criterion.
Traps
Diagnosing malnutrition from albumin alone; calculating BMI in a patient with marked edema without commenting on fluid; using a single mid-upper arm circumference without age and sex reference; confusing sensitivity with specificity; treating a positive screen as a diagnosis.