Humoral Immunity in Pediatric Patients with Recurrent Infections: A Study in the Pediatric II Service of the “Ruíz y Páez” University Hospital Complex, Ciudad Bolívar, Bolívar State, Venezuela

Background: Infectious processes are the leading cause of pediatric consultation, and recurrent or severe infections may indicate primary immunodeficiencies (PIDs), which comprise more than 484 rare diseases affecting the immune response. The nature and severity of infections depend on the component of the immune system affected, with defects in humoral immunity being a frequent cause of severe respiratory infections. Evaluation of blood immunoglobulin (Ig) levels is essential for the identification of PIDs. However, the prevalence and specific immunoglobulin levels in this population still require further study in our region. Objective: To evaluate immunoglobulin levels (IgA, IgG, IgM) in pediatric patients with recurrent infections and to determine their relationship with possible primary immunodeficiencies (PID) in the Pediatrics Service II of the University Hospital Complex “Ruíz y Páez” of Ciudad Bolívar. Methods: A descriptive, prospective, cross-sectional study was performed on 30 pediatric patients with at least one alarm sign according to the Jeffrey Modell Foundation. Data included age, gender, type of infections, and serum immunoglobulin levels. Igs levels were analyzed and compared between groups. For the comparison of variables, an ANOVA was applied, considering as statistically significant those results with a confidence margin greater than 95% or a p-value less than 0.05. In addition, patients were classified into possible cases of PID, based on both immunoglobulin levels and clinical findings, following the diagnostic criteria established by the Society for Pediatric Immunology and clinical consensus. Diagnostic confirmation of PID was made by clinical evaluation, immunoglobulin analysis. Results: The most frequent infections were pneumonia (n = 6) 20.00% and cutaneous abscesses n = 6 (20.00%). The distribution by gender was females (n = 18) 60.00% and (n = 12) males 40.00% with a mean age of 4.2 ± 1.8 years. Immunoglobulin levels presented the following means (± SD): IgA. 45.6 ± 12.3 mg/dL, with 10% of patients showing low levels (<5.0 mg/dL); IgG, 950 ± 150 mg/dL, within normal range in most; and IgM, 88.4 ± 24.5 mg/dL, with 6.67% of elevated levels. Low IgA levels were observed in cases of pneumonia (n = 3) 10.00%, a and otitis (n = 3) 10.00%, and elevated IgM levels in patients with skin abscesses (n = 2) 6.67%. Statistical comparison of immunoglobulin levels between groups revealed no significant differences (p > 0.05). Diagnosis of possible PID: 21 patients were identified with profiles suggestive of PID, in particular, selective IgA deficiency (n = 8) 38.10% and common variable immunodeficiency (CVID) (n = 7) (33.33%) and hyper IgM (n = 6) 28.57%. The diagnostic classification was based on clinical and laboratory criteria, not only on immunoglobulin levels. Conclusions: Although no statistically significant differences in immunoglobulin levels were found between groups, the high percentage of patients with profiles suggestive of PID reinforces the importance of performing complete immunologic evaluations in pediatric patients with recurrent infections. Diagnostic confirmation requires clinical correlation and, in some cases, additional studies, so it is recommended to strengthen immunologic evaluation protocols in our context.