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Printed on 7/20/2026
For informational purposes only. This is not medical advice.
The Nutritional Risk Index (NRI) is a nutrition-related risk score used to stratify risk of complications and adverse outcomes associated with undernutrition. It is applied in hospitalized and chronic-disease settings, including older populations.
Formula: NRI is a composite nutrition-risk index where lower totals indicate higher risk.
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Collect serum albumin (g/dL), current weight (kg), and usual weight (kg) from the patient's history. Usual weight is the patient's stable pre-illness weight—typically the weight 3-6 months prior to the current illness or hospitalization. These values are required for the NRI formula.
NRI = 1.519 × albumin (g/dL) × 100 + 0.417 × (current weight / usual weight) × 100. The formula was originally developed by Buzby and colleagues for nutritional risk assessment in gastrointestinal surgical patients. The weight ratio reflects recent weight change as a marker of nutritional decline.
Classify: above 100 = not at nutritional risk; 97.5-100 = mild risk; 83.5-97.4 = moderate risk; below 83.5 = severe risk. Moderate to severe NRI risk should trigger dietary assessment, dietitian referral, consideration of oral nutritional supplements, and monitoring for complications associated with malnutrition.
Surgical Teams & Anesthesiologists
NRI was originally validated in gastrointestinal surgical populations. Pre-operative NRI identifies patients at moderate to severe nutritional risk who benefit from 7-14 days of pre-operative nutritional supplementation to reduce post-operative complications including infection, wound dehiscence, and anastomotic failure.
Dietitians & Nutritionists
Use NRI at hospital admission to rapidly stratify nutritional risk using standard laboratory data. Patients with NRI below 97.5 should receive early dietitian assessment to develop individualized nutrition care plans before complications of malnutrition develop.
Oncologists & Oncology Dietitians
Cancer-related malnutrition is prevalent (30-70% of patients) and worsens treatment tolerance and survival. NRI provides an objective lab and weight-based nutritional risk score at cancer diagnosis and before chemotherapy cycles to guide nutritional intervention intensity.
Clinical Researchers
NRI is used as a baseline nutrition stratification variable in surgical and medical trials examining the relationship between nutritional status and clinical outcomes. Its reproducibility and long track record support its use as a validated historical comparator in research.
Internists & Chronic Disease Teams
NRI scores predict complication risk and mortality in hospitalized patients with heart failure, chronic kidney disease, and liver cirrhosis. Serial monitoring in these high-risk populations identifies progressive nutritional deterioration requiring intervention before overt malnutrition develops.
The current-to-usual weight ratio in NRI is only meaningful if usual weight is accurately determined. Patients may not recall their stable weight accurately. Use pre-illness weight documented in medical records, pharmacy dispensing records (for weight-adjusted medications), or carer-reported weight where available.
Serum albumin is a negative acute-phase reactant that falls with systemic inflammation independently of nutritional intake. Interpret NRI cautiously in acutely ill patients or those with active inflammatory conditions—albumin-based nutritional indices will overestimate nutritional risk in the setting of acute-phase response.
The original NRI (Buzby formula) uses current weight versus usual weight and was developed for surgical adults. GNRI (Bouillanne formula) uses current weight versus ideal body weight and was developed for hospitalized older adults. Use GNRI when the Geriatric Nutritional Risk Index is appropriate for your specific patient population.
When calculating NRI, document in the clinical notes where the usual weight value came from (patient self-report, medical records, carer history, etc.). This provides an audit trail and allows future clinicians to assess the reliability of the NRI calculation.
Fluid retention from heart failure, liver disease, or renal disease adds body weight that does not reflect nutritional status. In edematous patients, current body weight will overestimate true tissue weight, inflating NRI and underestimating malnutrition risk. Clinical assessment of fluid status is essential.
NRI uses only two data points. Combine with a brief dietary intake history, functional assessment, and anthropometric measurements (mid-arm circumference, handgrip strength) for comprehensive nutritional characterization. NRI flags risk; comprehensive assessment identifies cause and guides specific intervention.
For patients with NRI below 83.5 awaiting elective surgery, guidelines support delaying non-urgent surgery by 7-10 days to allow pre-operative nutritional optimization. This window allows significant improvements in albumin, immune function, and muscle protein synthesis that reduce surgical complication risk.
NRI weight ratio captures extent of weight loss from usual weight. A patient who has lost 15% of body weight has an NRI weight ratio of 0.85. Combine with time course of weight loss—rapid weight loss over weeks to months is more clinically significant than the same loss over years.
NRI has longstanding validation in hospitalized and chronic-care populations for nutrition-related risk prediction.
Lower NRI scores indicate greater nutrition-related risk and support intensified nutrition care planning.
Use for nutrition-risk stratification when clinicians need a standardized prognostic nutrition index.
Biomarker and weight-related components can be influenced by fluid status and non-nutritional illness factors.
For related assessments, see GNRI, CONUT and MUST Score.
Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.
April 21, 2026 · trust-baseline
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Open