Reliability of Malnutrition Assessment Based on Selected Laboratory Parameters in Heart Transplant Recipients—A Retrospective Single-Centre Pilot Study from Poland

<b>Background:</b> Malnutrition is a common yet often underestimated risk factor for adverse outcomes in hospitalized patients, including heart transplant recipients. Assessing nutritional status in this population is challenging due to comorbidities, pharmacotherapy, and the urgent nature of surgery. This study aimed to evaluate the reliability of routinely measured laboratory and anthropometric parameters in diagnosing malnutrition in heart transplant patients. <b>Methods:</b> This retrospective study included 53 adult patients who underwent orthotopic heart transplantation between 2021 and 2024 at the Silesian Center for Heart Diseases in Zabrze, Poland. Anthropometric data (gender, age, BMI) and laboratory parameters-albumin, total protein, hemoglobin, cholesterol, <i>C</i>-reactive protein (CRP), and neutrophil-to-lymphocyte ratio (NLR)-were analyzed. Malnutrition was defined as BMI < 22 kg/m². Cut-off points were based on literature data. Correlations between laboratory parameters and nutritional status were assessed, and concordance in malnutrition classification was evaluated. <b>Results:</b> Malnutrition criteria were met by 15% of patients. Only CRP predicted malnutrition risk, though its values did not differ significantly between BMI groups (<i>p</i> = 0.106). Negative correlations were found between CRP and total protein (-0.342; <i>p</i> = 0.012), albumin (-0.666; <i>p</i> < 0.0001), cholesterol (-0.287; <i>p</i> = 0.037), and hemoglobin (-0.383; <i>p</i> = 0.0046). A positive correlation was observed between CRP and NLR (0.333; <i>p</i> = 0.014). <b>Conclusions:</b> Malnutrition assessment in heart transplant recipients should not rely solely on individual laboratory parameters. A multifactorial approach integrating biochemical, anthropometric, and clinical data is necessary. Further research is needed to identify novel biomarkers to improve malnutrition risk evaluation and guide nutritional interventions in this population.