Iron deficiency anemia (IDA) continues to be a global public health concern, mostly in the developing countries. However, precise epidemiological data on childhood IDA in Croatia are lacking. In order to establish its frequency, underlying etiologies, the rationale for tertiary care visits, diagnostic practices, and current treatment regimens of IDA, medical records of children referred to pediatric hematologists for iron deficiency in a five-year period at tertiary institutions (Zagreb, Rijeka, Split, Osijek) throughout Croatia were retrospectively analyzed. Eight hundred and sixty-four children, predominately of preschool age, were referred mainly by the primary care pediatricians, who, in general, performed basic diagnostics but failed to initiate oral iron therapy in half of the patients. Approximately one-third of patients were symptomatic, with inadequate nutrition prevailing as underlying etiology. Dextriferron was the preferred iron formulation among hematologists, with a median dose of 5 mg/kg, with acceptable compliance rates (63.5–93.2%). Hospital admission rates varied among the centers (9.4–35%), and so did transfusion policies (6.4–22.9%). The greatest difference was observed in the frequency of parenteral iron administration (0.3–21.5%). In conclusion, the burden of childhood IDA, even in a high-income country, remains substantial, necessitating consistent implementation of national guidelines and additional education of primary health care providers.

Background/Objectives: Wilms’ tumor (WT) is the most common malignant renal tumor in childhood, and although survival rates are high, a subset of patients with high-risk disease remain prone to treatment resistance and relapse. Increasing evidence suggests that the tumor microenvironment, particularly tumor-associated macrophages (TAMs), may influence tumor behavior and therapeutic response. This study aimed to characterize M1 and M2 macrophage infiltration in WT treated with neoadjuvant chemotherapy according to the International Society of Pediatric Oncology (SIOP) protocol and to evaluate their association with clinicopathological features. Methods: Tumor tissue samples from 46 pediatric patients were analyzed using double immunohistochemical staining for CD80 (M1) and CD163 (M2) macrophages. TAM density and M1/M2 ratios were quantified in viable tumor areas and correlated with clinical, laboratory, and pathohistological parameters. Results: Total TAM counts were significantly higher in tumors with a volume ≥ 500 mL and in unifocal tumors. Both M1 and M2 macrophages were more abundant in larger tumors; however, M2 macrophages predominated overall. The M1/M2 ratio was positively associated with total TAM counts and was significantly higher in tumors with larger volume, elevated serum neuron-specific enolase, and increased creatinine levels. Regressive histological subtypes exhibited a higher M1/M2 ratio compared with other subtypes. No significant associations were observed between macrophage infiltration and tumor stage or risk group. Conclusions: WT treated with neoadjuvant chemotherapy demonstrates low overall macrophage infiltration with a predominance of M2 macrophages. TAM polarization appears to be associated with tumor burden and selected biochemical parameters, highlighting the potential relevance of macrophages as biomarkers and therapeutic targets in WT.

Background/Objectives: The prevalence of allergic diseases has markedly increased in developed countries, with environmental and dietary factors considered important contributors. Folic acid is an essential micronutrient involved in one-carbon metabolism and DNA methylation, playing a key role in epigenetic regulation of immune function. Both high and low folate exposure have been associated with allergic outcomes, but the data on postnatal folate status in paediatric populations remain limited. This study aimed at assessing serum folate status in children with atopic diseases compared with children without chronic allergic disease in Croatia. Methods: This cross-sectional study included 292 paediatric patients from the University Hospital in Split and a paediatric primary care practice between January 2024 and January 2025. Serum folic acid concentrations were measured using electrochemiluminescence immunoassay. Additional laboratory parameters included vitamin B12, total IgE levels, and eosinophil counts. Demographic and clinical data were obtained from medical records. Statistical analyses included Chi-square tests, Mann–Whitney U tests, linear regression modelling, and analysis of covariance with statistical significance set at p < 0.05. Results: Folic acid deficiency was present in 66.4% of all participants. Children with atopic diseases were significantly more likely to have folate deficiency and had lower mean serum folate concentrations compared to children without allergic disease. There were no significant differences in folate levels between children with and without asthma. Lower folate levels were associated with higher IgE levels, higher eosinophil counts, and older age. When controlling for the effects of age on folic acid levels, the differences between participants with and without atopic diseases remained significant. Conclusions: Folic acid deficiency is highly prevalent among children in the Mediterranean region of Croatia and is significantly associated with atopic diseases and markers of allergic inflammation. These findings highlight a potential role of folate status in paediatric allergic disease and support the need for longitudinal studies to clarify causality and potential clinical implications.