Peripheral Hematological and Immune-Endocrine Markers in Children with Specific Learning Disorder: An Exploratory Retrospective Case–Control Study

Background: Specific learning disorder (SLD), termed “specific learning disability” in the Human Phenotype Ontology (HP:0001328), is a heterogeneous neurodevelopmental disorder, and the association between peripheral biological changes and cognitive function remains not well understood. Peripheral hematological and immune-endocrine biomarkers and their relationships with neuropsychological evaluations were evaluated in children with SLD. Methods: In this retrospective case–control study, we evaluated the peripheral biomarkers of a complete blood count and biochemical panel in 103 children with SLD and 102 well-child outpatient controls. Within the SLD group, we examined the association of systemic inflammatory indices with cognitive domains as assessed by the Wechsler Intelligence Scale for Children—Revised. Results: Group comparisons revealed modest peripheral changes, including reduced mean platelet volume (MPV) and increased eosinophil counts, that persisted after false discovery rate correction. Both differences remained significant after adjustment for age and sex. Inflammatory indices from complete blood count showed poor discriminative validity and were not strongly related to the global intelligence quotient. Exploratory analyses revealed only nominal, domain-specific associations between systemic inflammation indices and particular Wechsler subtests for verbal abstraction and visuospatial organization that did not survive multiple-comparison correction. Conclusions: The findings indicate a selective peripheral hematological pattern in SLD rather than evidence of generalized systemic inflammation. The evaluated indices showed limited discriminative utility and were not independently associated with global cognitive performance after multiple-testing correction. They should not be considered screening or diagnostic biomarkers for SLD. The selective pattern of lower MPV and higher eosinophil count observed in children with SLD appears to be novel but should be considered preliminary and requires independent confirmation in larger, prospectively recruited groups.