Nutritional Assessment
Preoperative nutritional assessment is the lab-and-bedside complement to the optimization protocols on the Perioperative Nutrition page. The reconstructive-urology and urogynecology audience meets this in every major elective case: a hypoalbuminemic patient walking into a radical cystectomy, ileal-conduit revision, augmentation cystoplasty, posterior urethroplasty, sacrocolpopexy with bowel involvement, or a free-flap reconstruction has a measurably higher complication risk that screening identifies and targeted intervention modifies.
This page collects the labs, screening tools, physical exams, and body-composition assessments that matter at the preoperative visit, organized by category. Individual labs link out to deep-dive pages.
Practice Guidance — When and What to Screen
The American College of Surgeons (ACS) NSQIP / AGS Best Practice Guidelines identify severe nutritional risk by any one of:[1]
- BMI < 18.5 kg/m²
- Serum albumin < 3.0 g/dL (without hepatic or renal dysfunction)
- Unintentional weight loss > 10–15% in 6 months
The ACS Strong for Surgery quality-improvement program adds:[1]
- BMI < 19, weight loss > 8 lbs in 3 months, poor appetite (< 2 meals/day or eating < ½ of meals), or inability to take food orally → refer to RD
- Screening albumin for everyone
- Immune-modulating supplementation for complex surgery
For the reconstructive practice this maps directly onto every patient on the radical cystectomy / urinary-diversion / augmentation / complex urethroplasty / free-flap track.
Laboratory Tests
Serum Proteins and Inflammatory Markers
| Lab | Half-life | Threshold | Reconstructive use | Deep dive |
|---|---|---|---|---|
| Serum albumin | ~ 20 days | < 3.5 g/dL abnormal; < 3.0 g/dL severe risk | Strongest preoperative predictor of complications across plastic / reconstructive populations (200k-pt analysis); ASPEN notes it reflects inflammation and nutritional status[2] | Serum Albumin |
| Prealbumin (transthyretin) | ~ 2 days | < 15 mg/dL | More responsive to acute change; useful for tracking response to nutrition support[2][3] | Prealbumin |
| Transferrin | ~ 8 days | < 200 mg/dL low | Historical adjunct; confounded by iron status and inflammation[2] | Transferrin |
| C-reactive protein (CRP) | hours | — | Anchors interpretation of low albumin / prealbumin: high CRP → inflammation-driven, not pure malnutrition. Part of the GLIM etiologic criterion.[4][5] | CRP |
Complete Blood Count and Related
- Hemoglobin / CBC — identifies anemia (iron, B12, folate deficiency) and provides general health status; preoperative anemia correction is part of every ERAS bundle.[6]
Micronutrient Panel
High-yield in post-bariatric, GLP-1 RA, oncologic, post–ileal-resection (conduit / neobladder / augmentation), and elderly patients.
| Lab | Biomarker | Deficiency cutoff | Reconstructive flag | Deep dive |
|---|---|---|---|---|
| Vitamin D | 25(OH)D | < 30 nmol/L severe; 25–50 nmol/L insufficient | Deficient in up to 100% of bariatric patients; bone and immune | Vitamin D |
| Iron | Ferritin (+ TIBC) | < 30 µg/L (< 10 = anemia risk) | Adjust for inflammation (acute-phase reactant) | Iron & Ferritin |
| Vitamin B12 | Cobalamin (+ MMA / homocysteine) | < 150 pmol/L deficient; 150–221 marginal | Universal after ileal-conduit / neobladder / RYGB / GLP-1 RA; cross-link to post-diversion surveillance | Vitamin B12 |
| Folate | RBC folate | < 400 nmol/L | Critical in reproductive-age women | Folate |
| Zinc | Plasma zinc | < 11 µmol/L (M); < 10.4 µmol/L (F) | Wound healing substrate; confounded by inflammation | Zinc |
| Vitamin A | Retinol | < 0.7 µmol/L | Post-BPD/DS surveillance | Vitamin A |
| Thiamine (B1) | ETK activity | > 25% increase = deficient | Alcoholism, prolonged NPO, refeeding-syndrome risk | Thiamine |
| Copper | Serum copper + ceruloplasmin | Low values | Annually post-RYGB / BPD-DS; deficiency mimics B12 myeloneuropathy | Copper |
Additional Labs
- HbA1c / glucose — glycemic control directly affects wound healing; perioperative target generally HbA1c < 7%.
- Serum creatinine — adjunctive marker of muscle mass if renal function is intact.
- IGF-1 — anabolic-activity marker, less inflammation-confounded than albumin; not in routine practice.
- Lipid panel — low cholesterol can be a malnutrition-and-inflammation signal.
Validated Screening Tools
A 2024 systematic review and network meta-analysis identified MUST as having the highest diagnostic accuracy for preoperative malnutrition (sensitivity 86%, specificity 89%), confirmed in a 2025 multicenter prospective surgical cohort.[7][8] Full comparison and deep dive on each tool: Nutritional Screening Tools.
| Tool | Strengths | Notes |
|---|---|---|
| MUST (Malnutrition Universal Screening Tool) | Highest pooled accuracy in surgical cohorts | BMI + weight loss + acute-illness-no-intake |
| NRS-2002 (Nutritional Risk Screening) | ESPEN standard | Stratifies nutritional status + disease severity |
| MNA-SF (Mini Nutritional Assessment — Short Form) | 6 items, < 5 min | Best in geriatric surgical populations |
| GLIM (Global Leadership Initiative on Malnutrition) | Consensus diagnostic framework (not a screen) | Phenotypic + etiologic two-step (see below) |
GLIM Diagnostic Criteria
The Global Leadership Initiative on Malnutrition is the current international consensus framework for diagnosing (not screening) malnutrition. Two-step:[4][6]
- Screen with a validated tool (MUST or NRS-2002).
- Diagnose when at least one phenotypic criterion AND at least one etiologic criterion are present:
| Phenotypic (any 1) | Etiologic (any 1) |
|---|---|
| Unintentional weight loss ≥ 5% in 6 months (or > 10% beyond 6 months) | Reduced food intake or assimilation |
| Low BMI (< 20 if age < 70; < 22 if ≥ 70) | Disease burden / inflammation (acute or chronic) |
| Reduced muscle mass | — |
Severity is graded on weight loss, low BMI, and muscle mass loss.
Physical and Functional Assessments
- Handgrip strength (dynamometry) — inexpensive bedside marker of muscle function. Grip strength below sex-specific cutoffs predicts postoperative complications, prolonged LOS, and delayed ambulation.[9][10] Deep dive: Handgrip Strength.
- Nutrition-focused physical exam — subcutaneous fat loss, temporal wasting, quadriceps / deltoid / interosseous wasting, dependent edema.[4][6]
- Anthropometrics — weight, height, BMI, mid-arm circumference, calf circumference (GLIM-endorsed when body-composition devices unavailable), skinfold thickness.[11]
Body Composition Assessment
GLIM-endorsed methods for quantifying muscle mass (order of preference):[11]
- CT-based skeletal muscle index (SMI) at L3 — gold standard; often available from staging scans in oncologic patients (e.g., bladder cancer pre-cystectomy).
- Bioelectrical impedance analysis (BIA) — portable, inexpensive, widely available.
- Dual-energy X-ray absorptiometry (DXA) — accurate but less routine preoperatively.
- Anthropometric measures + trained physical examination when imaging unavailable.
Deep dive: Body-Composition Assessment.
Bottom Line
A practical preoperative nutritional assessment for the reconstructive patient combines:
- Serum albumin (± prealbumin, CRP) as the lab anchor.
- A validated screening tool (MUST or NRS-2002).
- Targeted micronutrient labs by population — universal B12 / vitamin D / iron for any patient on ileal-bowel reconstruction, GLP-1 RA, post-bariatric, oncologic, or elderly.
- Handgrip strength as the bedside functional marker.
- GLIM when formal malnutrition diagnosis is needed for documentation, optimization, and downstream insurance / RD referral.
Positive screen → optimization protocol on the Perioperative Nutrition page (oral nutritional supplements, immunonutrition, prehabilitation, GLP-1 RA management).
References
1. American College of Surgeons. Geriatric Surgery Verification Program Standards. ACS; 2019.
2. 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
3. Keller U. Nutritional laboratory markers in malnutrition. J Clin Med. 2019;8(6):E775. doi:10.3390/jcm8060775
4. Cederholm T, Bosaeus I. Malnutrition in adults. N Engl J Med. 2024;391(2):155-165. doi:10.1056/NEJMra2212159
5. McClave SA, DiBaise JK, Mullin GE, Martindale RG. ACG clinical guideline: nutrition therapy in the adult hospitalized patient. Am J Gastroenterol. 2016;111(3):315-34. doi:10.1038/ajg.2016.28
6. Schuetz P, Seres D, Lobo DN, et al. Management of disease-related malnutrition for patients being treated in hospital. Lancet. 2021;398(10314):1927-1938. doi:10.1016/S0140-6736(21)01451-3
7. 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
8. 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
9. 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
10. Zhou J, Liu X, Guo X, et al. Grip strength is an important predictor for nutritional risk and early postoperative ambulation in gastrointestinal tumors undergoing laparoscopic surgery: a prospective multicenter clinical study. World J Surg Oncol. 2023;21(1):273. doi:10.1186/s12957-023-03163-x
11. 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