Obesity and bariatric surgery are global challenges; however, long-term postoperative patients may develop disorders of iron and vitamin metabolism that culminate in anemia. Timely laboratory surveillance is essential to detect preclinical deficiencies.

The aim of the study: to evaluate changes in anemia panel indicators in patients after sleeve gastrectomy in the long-term postoperative period.

Materials and methods. A retrospective cohort of 114 adults with morbid obesity who underwent primary sleeve gastrectomy was analyzed. Preoperative anthropometry and anemia panel were within reference limits. Laboratory follow-up included hemoglobin, ferritin, serum iron, transferrin, and vitamin B12, assessed preoperatively and at 36 months after SG (overall observation period up to 60 months). Statistics: Kolmogorov–Smirnov, Levene, Wilcoxon for paired non-normal data, Pearson correlations, and multivariate linear regression (predictors: serum iron, ferritin, transferrin, vitamin B12); significance p < 0.05.

Results. At 36 months, anemia was present in 23.7 % (27/114). Compared with baseline, Hb decreased from 143 [136.0–150.0] to 136.7 [127.7–142.0] g/L (p = 0.001), serum iron from 20.8 [17.0–23.7] to 11.6 [3.9–18.8] μmol/L (p = 0.001), and ferritin from 126.2 [90.7–191.0] to 10.9 [9.4–95.5] ng/mL (p = 0.001); vitamin B12 showed no significant change (p = 0.053). Overall, anemia-panel disorders were frequent: latent iron deficiency 26.3 %, iron deficiency without anemia 15.8 %, iron-deficiency anemia 15.8 %, anemia without iron deficiency (likely B12/folate) 5.3 %, and combined deficiency 2.6 % (total 65.8 % with any disorder). Hemoglobin correlated with serum iron (r = 0.443; p = 0.001) and ferritin (r = 0.359; p = 0.001). In multivariate regression (F = 8.47; p < 0.001; R² = 0.237), independent predictors of hemoglobin were serum iron (β = 0.410; p = 0.001) and vitamin B12 (β = 0.180; p = 0.038); ferritin and transferrin were not independent predictors; no critical multicollinearity (VIF < 2.2).

Conclusions. Three years after sleeve gastrectomy, nearly one quarter of patients develop anemia and two thirds exhibit anemia-panel abnormalities, predominantly iron-related. Monitoring limited to hemoglobin misses a large burden of latent deficiency. A standardized follow-up that includes ferritin, serum iron, transferrin, and vitamin B12-alongside timely nutritional correction-should be routine to prevent progression to manifest anemia and its complications.