- Select albumin unit (g/dL or g/L) and enter serum albumin. If reported in g/dL, the calculator converts automatically — or select g/L to enter directly.
- For the Standard NRI: enter current weight (kg) and usual (pre-illness) weight (kg). The NRI score and risk category display instantly.
- If usual weight is unknown, use the Geriatric NRI (GNRI) section: enter current weight, height, and sex to derive IBW (BMI-22) as the reference.
- Interpretation thresholds are shown below each result — use alongside CRP, prealbumin, and dietary intake for a complete nutritional assessment.
All computation runs in your browser; no values are stored or transmitted.
When to Use
Use the Nutritional Risk Index (NRI) — Buzby et al. 1988 — to quantify malnutrition risk in any patient where serum albumin and weight data are available:
Validated populations
- Pre-operative assessment — validated in the VA Total Parenteral Nutrition trial (perioperative outcomes)
- Hemodialysis patients — NRI correlates with mortality and hospitalization rates
- CKD stages 3–5 — albumin <3.5 g/dL (35 g/L) is a KDOQI red flag for protein-energy wasting
- Peritoneal dialysis patients — hypoalbuminemia is more prevalent due to protein losses in dialysate
- Serial monitoring — track response to nutritional intervention (reassess monthly in HD)
Limitations
Albumin is a negative acute-phase reactant — inflammation independently lowers albumin regardless of nutritional status. In AKI or acute illness, NRI may underestimate true nutritional status. Always interpret alongside CRP, prealbumin, and clinical context. When usual body weight is unavailable, use the GNRI (section B below).
Pearls & Pitfalls
Albumin interpretation in CKD
In CKD patients, both malnutrition and chronic inflammation coexist (protein-energy wasting, PEW). Use NRI alongside serum CRP and prealbumin (transthyretin) for a complete picture. Prealbumin has a shorter half-life (~2 days) and responds faster to nutritional repletion than albumin (~20 days), making it better for monitoring short-term response.
Usual body weight: use stable pre-illness weight
Usual body weight (UBW) should be the patient's stable weight before the current illness episode — not a weight from 6+ months ago if there has been significant interval change. Document the source of UBW (patient report, medical records, clinic weight log). If uncertain, use the GNRI (BMI-22 reference) instead.
Pitfalls
(1) Albumin unit confusion: verify whether your lab reports in g/dL or g/L — the formula requires g/L. (2) Edema and ascites falsely elevate weight, making the weight ratio appear better than it is — note fluid status when interpreting. (3) Do not use NRI as the only nutritional assessment tool; KDOQI 2020 recommends a composite approach including dietary intake, body composition, and muscle function. (4) GNRI assumes BMI of 22 as ideal — not appropriate for patients with significant obesity at baseline.
Why Use It
Malnutrition in CKD and dialysis patients is independently associated with mortality, hospitalization, and cardiovascular events. The NRI provides a simple, objective, validated assessment from two readily available measurements — serum albumin and body weight — without requiring detailed dietary recall or complex body composition testing. It is one of the most widely cited nutritional assessment tools in surgical and nephrology literature, and is explicitly referenced in KDOQI 2020 nutrition guidelines as part of the PEW (protein-energy wasting) diagnostic framework. The GNRI variant extends its utility to patients in whom usual weight is unavailable, a common scenario in frail elderly and dialysis-dependent patients.
Nutritional Risk Index Calculator
Section A uses the standard NRI formula (requires usual weight). Section B uses the Geriatric NRI (GNRI) when usual weight is unknown.
A. Standard NRI (usual weight known)
NRI = (1.519 × albumin g/L) + (41.7 × current wt / usual wt) · Buzby GP et al. Am J Surg 1980; VA TPN Study NEJM 1991.
B. Geriatric NRI (GNRI) (usual weight unknown)
GNRI = (1.489 × albumin g/L) + (41.7 × min(current wt / IBW, 1)) · IBW = 22 × height² (m²) · GNRI cutoffs: ≥98 no risk · 92–<98 low · 82–<92 moderate · <82 major risk.
Next Steps
Use the NRI / GNRI result to guide nutritional intervention:
- NRI >100 / GNRI ≥98 (Well-nourished / No risk): No significant nutritional risk by NRI. Continue routine dietary monitoring. Reassess at next scheduled visit.
- NRI 97.5–100 / GNRI 92–<98 (Mild / Low risk): Dietary counseling. Optimize protein-energy intake (0.8–1.0 g/kg/day protein for non-dialysis CKD, 1.2 g/kg/day for HD). Reassess in 1–3 months.
- NRI 83.5–<97.5 / GNRI 82–<92 (Moderate risk): Protein-energy wasting (PEW) likely. Renal dietitian referral. Oral nutritional supplements (ONS). Check CRP to quantify inflammatory contribution. Reassess monthly.
- NRI <83.5 / GNRI <82 (Severe / Major risk): Urgent dietitian referral. Initiate oral nutritional supplements; consider intradialytic parenteral nutrition (IDPN) if on HD. Address underlying inflammation. Serial albumin and prealbumin monthly. Consider multidisciplinary PEW care plan per KDOQI 2020.
Evidence & References
NRI Formula & Interpretation
| NRI Score | Nutritional Risk Category |
|---|---|
| >100 | Well-nourished (no nutritional risk) |
| 97.5–100 | Mild nutritional risk |
| 83.5–<97.5 | Moderate nutritional risk |
| <83.5 | Severe nutritional risk |
GNRI Cutoffs
| GNRI Score | Nutritional Risk Category |
|---|---|
| ≥98 | No nutritional risk |
| 92–<98 | Low nutritional risk |
| 82–<92 | Moderate nutritional risk |
| <82 | Major nutritional risk |
References
- Buzby GP, Mullen JL, Matthews DC, et al. Prognostic nutritional index in gastrointestinal surgery. Am J Surg. 1980;139(1):160–167.
- The Veterans Affairs Total Parenteral Nutrition Cooperative Study Group. Perioperative total parenteral nutrition in surgical patients. N Engl J Med. 1991;325(8):525–532.
- Yamada K, Furuya R, Takita T, et al. Nutritional risk index as a predictor of mortality in patients on maintenance hemodialysis. Clin Exp Nephrol. 2008.
- Ikizler TA, Burrowes JD, Byham-Gray LD, et al. KDOQI Clinical Practice Guidelines for Nutrition in CKD: 2020 Update. Am J Kidney Dis. 2020;76(3)(Suppl 1):S1–S107.
