Thin basement membrane nephropathy as a cause of recurrent haematuria in childhood.

A survey of 69 children presenting with recurrent or persistent haematuria and submitted to percutaneous renal biopsy at this hospital over a 17-year period, was performed to establish the incidence of thin basement membrane nephropathy (TBMN). A diagnosis of primary glomerular disease was established in 44 (IgA nephropathy in 16, Alport's syndrome in 13 and other varieties of glomerulonephritis in 15). Of the remaining 25 patients in whom light microscopical and immunochemical examination revealed no abnormalities, material for electron microscopy was available in 11. In eight of these (five of whom had a family history), TBMN was diagnosed on the basis of ultrastructural morphometric evaluation of glomerular basement membrane thickness. Assuming a similar proportion of the remaining 14 patients with renal biopsy specimens normal by light microscopy had TBMN, the probable frequency of this abnormality in the whole series would be 26%, very similar to that of IgA nephropathy. In the eight TBMN patients the mean glomerular basement membrane thickness ranged between 181 and 236 nm, whilst in 'control' biopsies from children with 'minimal change' nephrotic syndrome or IgA nephropathy, the mean thickness ranged between 242 and 333 nm.