Nutritional Assessment
Assess nutrition early before major elective reconstruction, including urinary diversion, augmentation and flap surgery. Recent weight loss, reduced intake, impaired assimilation and loss of muscle require attention even when BMI or serum albumin is normal. Screening identifies patients who need a fuller assessment; the intervention depends on the findings and the time available before surgery.[1][2]
This is the assessment companion to Perioperative Nutrition, which covers treatment and perioperative feeding.
Screening and Referral
Use a validated screen and ask about weight trajectory, intake, gastrointestinal symptoms and functional decline. Refer patients with a positive screen or concerning clinical findings to a dietitian. The ACS Strong for Surgery checklist identifies low BMI, recent weight loss, poor intake and inability to eat as referral triggers. Its albumin testing item applies to inpatient surgery and not to every surgical patient.[3] The ACS Geriatric Surgery Verification standards cite the Strong for Surgery checklist as an example: BMI below 19, unintentional weight loss of more than 8 pounds in 3 months, eating less than half of meals or fewer than two meals a day, or inability to take food orally; the checklist calls for dietitian referral after a positive item.[10]
ESPEN 2025 defines high metabolic risk, a definition carried forward from 2017, by any of the following:[1]
- Weight loss > 10–15% in six months.
- BMI < 18.5 kg/m².
- NRS-2002 ≥ 5 or SGA grade C.[1]
- Albumin < 30 g/L (3.0 g/dL), without hepatic or renal dysfunction.
The albumin criterion identifies operative risk; it does not make albumin a diagnostic test for malnutrition. For severe malnutrition and/or high metabolic risk, ESPEN recommends preoperative nutrition therapy even if surgery must be postponed (grade A, strong consensus), and suggests considering 10–14 days (grade B). Balance this against the urgency of the underlying disease; oral or enteral feeding is preferred when possible.[1]
Laboratory Assessment
Serum Proteins and Inflammation
| Test | Appropriate interpretation | Deep dive |
|---|---|---|
| Albumin | Prognostic marker affected by inflammation, fluid balance, synthesis and losses; does not measure protein intake or muscle stores | Serum Albumin |
| Prealbumin | Shorter half-life does not establish it as a test of response to nutrition support | Prealbumin |
| Transferrin | Mainly useful within iron studies; iron status and inflammation confound nutritional interpretation | Transferrin |
| CRP | Can help assess uncertain inflammatory burden; not mandatory for GLIM and cannot separate malnutrition from inflammation by itself | CRP |
Albumin and prealbumin should not substitute for clinical nutritional assessment or be used to titrate nutritional therapy.[4] A normal CRP does not establish adequate nutrition; low albumin with high CRP does not exclude concurrent malnutrition.[2]
Targeted Tests
Select tests from the history, examination, planned operation and relevant disease-specific guidance.
| Clinical question | Assessment | Companion |
|---|---|---|
| Anemia before major surgery | CBC; investigate the cause, including iron status and other deficiencies when indicated | Preoperative Labs, Iron & Ferritin |
| Ileal reconstruction, bariatric surgery, restricted diet or neurologic symptoms | B12 testing according to anatomy and clinical context; follow the separate annual post-diversion surveillance guidance where applicable | B12, Diversion Surveillance |
| Suspected bone disease or relevant malabsorption | Selective 25-hydroxyvitamin D assessment | Vitamin D |
| Macrocytosis, restricted diet or malabsorption | B12 and folate evaluation, with assay-specific interpretation | Folate |
| Marked malabsorption, selected bariatric procedures or suggestive symptoms | Targeted trace element / fat-soluble vitamin testing | Zinc, Copper, Vitamin A |
| Prolonged poor intake, vomiting, alcohol-related risk or refeeding | Assess thiamine risk and electrolytes; suspected urgent deficiency requires treatment without waiting for a laboratory result | Thiamine |
For diabetes, ADA 2026 recommends a preoperative A1c goal of < 8% within 3 months before elective surgery, with individualized risk-benefit assessment (grade C); postponement on A1c or glucose management indicator alone is not recommended.[5]
Screening Tools and Diagnostic Assessment
| Tool | Role |
|---|---|
| MUST | Brief risk screen using BMI, weight loss and the acute-disease effect on intake |
| NRS-2002 | Hospital nutritional-risk screen incorporating nutritional impairment, disease severity and age |
| MNA-SF | Brief screen developed for older adults |
| SGA | Clinical assessment using history and examination |
| GLIM | Diagnostic framework after risk screening; requires phenotypic and etiologic findings |
In a 2024 review of 16 studies (5,695 adults scheduled for surgery), a nine-study MUST meta-analysis (3,394 patients) estimated 85% sensitivity and 89% specificity against SGA; 11 of the 16 studies had high risk of bias.[6] A 2025 cohort of 1,649 major abdominal surgery patients also supported MUST, although MNA-SF had a higher ordinal AUC. These findings support screening followed by assessment; they do not identify a single universally superior test or support automatic treatment from the screen alone.[6][7]
See Nutritional Screening Tools for application and scoring.
GLIM: Diagnosis After Screening
The 2025 update retains the requirement for at least one phenotypic and one etiologic criterion. Assess all five criteria where possible; missing measurements should not be mistaken for absence of malnutrition.[2]
| Phenotypic criteria | Etiologic criteria |
|---|---|
| Unintentional weight loss > 5% within six months or > 10% beyond six months | Intake ≤50% of energy requirements for >1 week, any reduction for >2 weeks, or a chronic gastrointestinal condition impairing assimilation or absorption |
| Low BMI: < 20 kg/m² before age 70, < 22 at age ≥ 70; for Asian populations, < 18.5 before age 70 or < 20 at age ≥ 70 | Disease burden / inflammation, judged clinically with laboratory support when needed |
| Reduced muscle mass using an appropriate validated method |
CRP is useful when inflammation is uncertain, but it is not required in every patient. Albumin and prealbumin are not diagnostic criteria. Grade severity using the phenotypic findings and the applicable GLIM guidance.[2]
Examination, Function and Body Composition
Assess fat and muscle loss (subcutaneous fat, temporal, quadriceps and deltoid wasting), dependent edema, weight history and dietary intake. Weight, height, BMI and calf or mid-arm circumference are recorded as part of the anthropometric assessment. Handgrip strength measures function; it is useful alongside the assessment but does not replace a muscle-mass measurement for GLIM.[8][2]
DXA, BIA, CT, ultrasound and other validated methods may quantify muscle mass according to availability and population-specific cutoffs. Use existing clinically indicated CT scans when appropriate; GLIM does not rank CT above every other method or require a new CT solely for nutritional screening. Trained examination or anthropometry can be used where instrumental assessment is unavailable.[9][2]
Practical Sequence
- Screen early and review weight loss, intake, disease burden and functional change.
- Assess a positive screen or clinical concern with dietetic input and an accepted diagnostic framework.
- Order tests that answer specific clinical questions, including anemia and anatomy-related deficiency risks.
- Agree on a nutrition plan and surgery timeline; monitor intake, tolerance, clinical recovery and function rather than aiming for a particular albumin or prealbumin concentration.
Treatment details are on Perioperative Nutrition.[1][4]
References
1. Weimann A, Bezmarevic M, Braga M, et al. ESPEN guideline on clinical nutrition in surgery — Update 2025. Clin Nutr. 2025;53:222–261. doi:10.1016/j.clnu.2025.08.029. Full guideline.
2. Jensen GL, Cederholm T, Correia MITD, et al. GLIM consensus approach to diagnosis of malnutrition: A 5-year update. JPEN J Parenter Enteral Nutr. 2025. doi:10.1002/jpen.2756.
3. American College of Surgeons. Strong for Surgery: Nutrition Checklist. 2024. Official checklist.
4. Evans DC, Corkins MR, Malone A, et al. The use of visceral proteins as nutrition markers: an ASPEN position paper. Nutr Clin Pract. 2021;36(1):22-28. doi:10.1002/ncp.10588
5. American Diabetes Association Professional Practice Committee for Diabetes. 16. Diabetes Care in the Hospital: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1). doi:10.2337/dc26-S016.
6. Cheung HHT, Joynt GM, Lee A. Diagnostic test accuracy of preoperative nutritional screening tools in adults for malnutrition: a systematic review and network meta-analysis. Int J Surg. 2024;110(2):1090-1098. doi:10.1097/JS9.0000000000000845
7. Petra G, Kritsotakis EI, Gouvas N, et al. Multicentre prospective study on the diagnostic and prognostic validity of malnutrition assessment tools in surgery. Br J Surg. 2025;112(2):znaf013. doi:10.1093/bjs/znaf013
8. Norman K, Stobäus N, Gonzalez MC, Schulzke JD, Pirlich M. Hand grip strength: outcome predictor and marker of nutritional status. Clin Nutr. 2011;30(2):135-42. doi:10.1016/j.clnu.2010.09.010
9. Barazzoni R, Jensen GL, Correia MITD, et al. Guidance for assessment of the muscle mass phenotypic criterion for the Global Leadership Initiative on Malnutrition (GLIM) diagnosis of malnutrition. Clin Nutr. 2022;41(6):1425-1433. doi:10.1016/j.clnu.2022.02.001
10. Coleman J, Finlayson E, Katlic M, et al. Geriatric Surgery Verification Program Standards. American College of Surgeons; 2019. Standard 5.6 and appendices.