Abstract Knowingthe clinical warning signs of immunode - Knowingthe clinical warning signs of immunode - Knowing ciency (ID) in adulthood is crucial forearly detection forearly detection for of the over 200 forms of primary ID known to date. Many of these congenital diseases with a genetic background already manifest in childhood. Anti-body de ciency diseases represent an important ex-ception, with common variable immunode ciency (CVID)being the most common form of ID.  e me-dian age of onset of CVIDis 24 years. Unfortunately, the delay in diagnosis is still in excess of 4 years. Gen-eral practitioners as well as allergists play a particu-larly important role in early detection. ID patients
who present primarily withsigns of immune dysreg-ulation pose an even greater diagnostic challenge.  us, autoimmune cytopenia, in ammatory bowel diseases, or sarcoid-like granulomatous in amma-tion can bethe  rst manifestationin up to 20% of ID patients. Secondary forms of ID [e.g., due to long-term corticosteroid treatment, HIV- term corticosteroid treatment, HIV- term corticosteroid treatment, HIVinfection, leuke-mia, lymphoma, nephrotic syndrome, malabsorption syndrome] need to be di erentiated from primary antibody de ciency.