Testing-Yield Mismatch in Inpatient Micronutrient Assessment in Inflammatory Bowel Disease: A Real-World Implementation-Gap Analysis

Background/Objectives: Micronutrient deficiencies are common in inflammatory bowel disease (IBD) and contribute to anemia, impaired wound healing, neurologic injury, and adverse disease outcomes. Major societies, including ESPEN, ACG, and ECCO, recommend nutritional and micronutrient assessment in patients with IBD, yet few studies describe how comprehensively these recommendations are applied during hospitalization. This study aimed to characterize inpatient testing practices for vitamins B1, B6, B12, and zinc in hospitalized IBD patients, quantify deficiency frequency among those tested, and identify gaps between guideline-recommended and actual micronutrient assessment. Methods: A retrospective chart review was performed on adults with Crohn’s disease (CD) or ulcerative colitis (UC) hospitalized for an IBD flare at a tertiary care center. Demographics, comorbidities, and deficiency-associated clinical features were recorded. Yield was defined as the proportion of tested patients meeting institutional deficiency thresholds. Yield for each non-B12 micronutrient was compared with B12 as an internal benchmark. Results: Among 356 patients (285 CD, 71 UC), inpatient micronutrient testing was markedly imbalanced: B12 was tested in 97.2%, whereas B6, B1, and zinc were tested in only 34.8%, 30.6%, and 18.8%, respectively. Among those tested, deficiencies were common: B6 40.3%, zinc 32.8%, B1 22.9%, and B12 9.0%. Each non-B12 micronutrient yielded deficiency significantly more often per test than B12 (all p < 0.001), a testing-yield mismatch interpreted cautiously given selective testing of non-B12 nutrients. Deficiency frequencies did not differ significantly between CD and UC. Clinical contexts included tachycardia and edema (B1); elevated inflammatory markers and thromboembolism history (B6); anemia and neuropathy (B12); and diarrhea and hypoalbuminemia (zinc). Conclusions: Inpatient micronutrient assessment in IBD is heavily skewed toward B12, with B1, B6, and zinc under-tested despite a substantially higher yield of identified deficiency per test. This testing-yield mismatch represents a measurable implementation gap between guideline-recommended comprehensive assessment and actual inpatient practice; whether systematic panel-based assessment improves clinical outcomes warrants prospective evaluation.