Patient presents with recurrent infections, suggesting possible hypogammaglobulinemia.  Symptoms include sinusitis, bronchitis, pneumonia, otitis media, and gastrointestinal infections.  The patient reports increased frequency and severity of infections, often requiring antibiotic treatment.  Physical examination may reveal lymphadenopathy or hepatosplenomegaly.  Differential diagnoses include common variable immunodeficiency (CVID), X-linked agammaglobulinemia (XLA), and other primary immunodeficiencies.  Laboratory evaluation reveals decreased immunoglobulin levels (IgG, IgA, andor IgM) confirmed by quantitative immunoglobulin measurement.  Specific antibody responses to vaccines (e.g., pneumococcal, tetanus) may also be assessed.  Further testing, such as B cell counts and lymphocyte subset analysis, may be indicated to determine the underlying cause of hypogammaglobulinemia.  Diagnosis of hypogammaglobulinemia is based on clinical presentation, history of recurrent infections, and laboratory confirmation of low immunoglobulin levels.  Treatment typically involves immunoglobulin replacement therapy (IVIG or SCIG) to prevent infections and improve quality of life.  Patient education on infection prevention strategies is crucial.  Regular monitoring of immunoglobulin levels and response to treatment is essential.  ICD-10 coding for hypogammaglobulinemia will be based on the specific type and underlying cause, potentially including D80.  Medical billing for immunoglobulin therapy and associated laboratory tests will be documented accordingly.  The patient will require ongoing follow-up care with an immunologist to manage this chronic condition.