Glomerular thin basement membrane disease, a case series of seven patients diagnosed by electron microscopy

Introduction: Thin basement membrane disease (TBMD) is common among children with asymptomatic hematuria. Any patient with microscopic persistent hematuria without significant clinical and Para clinical abnormality should be worked up for this disease. The disease is familial and mostly inherited as autosomal dominant with mutation of the COL4A3 and COL4A4 genes. Renal biopsies appear normal by light microscopy. The definite diagnosis is made by electron microscopy. Demonstration of a uniform thinning of the glomerular capillary basement membrane confirms the diagnosis. The prognosis is usually excellent, so definite diagnosis and differentiation from Alport syndrome or Ig A nephropathy is very important. Materials and method: A total of seven patients were diagnosed during 15 years in electron microscopic department of Shiraz University of medical sciences since 2000 to 2014. The biopsies were fixed in glutaraldehyde 3% and after routine processing for electron microscopy, the ultrathin sections with 90 nanometer thickness were stained by uranium acetate and lead citrate, then studied with electron microscope. Results: The ages ranged from 4 up to 13 years. 4 patients were male and other 3 of them were female. All of them had persistent microscopic hematuria as the only finding. The kidney biopsy of all patients reported normal by light microscopy. Also immunofluorescence studies were negative. Electron microscopy revealed normal cellularity and thinning of the lamina densa of the glomerular capillary wall basement membrane measuring 100 to 200 nanometers in diameter. (Normally 300 to 350 nanometers) so they were diagnosed as glomerular thin basement membrane disease. Conclusion: In patients with persistent microscopic hematuria without any significant clinical presentation, electron microscopic study of kidney biopsy is mandatory for diagnosis of TBMD and differentiate It (which has a good prognosis) with other kidney disease with hematuria such as Alport syndrome or Ig A nephropathy (which the prognosis is not always benign).

Keywords:

Thin basement membrane disease , electron microscopy , asymptomatic hematuria , glomeruli