The Transition from Thin Basement Membranes to Typical Alport Syndrome Morphology in Children.

Some children with thin basement membranes (TBM) turn out to have Alport syndrome (AS). In our population of 58 children initially diagnosed with TBM, three were eventually diagnosed with AS. As a group, these three were first biopsied at a younger age, and had gross rather than microscopic hematuria. Only one had lamellations initially. Seven others had some degree of basement membrane lamellations at initial biopsy, but none of these have developed other features of AS. We concluded that at least 5% of children initially demonstrating TBM go on to manifest the classical electron-microscopic findings of AS during childhood. Episodes of gross hematuria with TBM can be a significant clue of AS. Genetic and/or immunofluorescent studies for type IV collagen, and continued long-term follow-up should be done in all children with TBM.