Nutrition Assessment and Nutrient Requirements
Core concepts
Assessment begins with identifying risk, then confirming and quantifying it. Know the validated screening tools (MUST, NRS-2002, MST, NUTRIC for ICU) and when each applies; screening is not the same as a full assessment. A complete assessment integrates history (intake, weight trajectory, GI symptoms, functional status), anthropometrics (current and usual weight, percent weight change, BMI, and for some patients mid-arm circumference), biochemical data interpreted with caveats (albumin and prealbumin are acute-phase reactants, not pure nutrition markers), and clinical exam for micronutrient deficiency signs.
Estimating requirements
Calorie needs: use indirect calorimetry when available; otherwise 25-30 kcal/kg/day for most stable adults, adjusting for obesity (hypocaloric high-protein approaches) and critical illness (avoid overfeeding early). Protein: 1.2-2.0 g/kg/day in critical illness, 1.2-1.5 g/kg in many hospitalized patients, higher in burns or major wounds, lower in untreated hepatic encephalopathy or severe renal failure without dialysis. Fluid and electrolytes follow maintenance and losses. Micronutrients deserve attention in prolonged illness, bariatric surgery, and malabsorption.
Traps
Questions often test the difference between screening and assessment, misuse of albumin as a nutrition marker, ideal vs actual body weight in obesity, and the harm of overfeeding (hyperglycemia, azotemia, increased CO2). Watch units: percent weight loss over time matters more than absolute weight.
Worked rule of thumb
Percent weight change = (usual weight − current weight) ÷ usual weight × 100. A 70 kg patient now at 63 kg has lost 10% - clinically significant if recent and unintentional, warranting aggressive nutrition planning.