CEMIC Medicine, Buenos Aires, Argentina Email: a.vilches{at}voyager.com.ar
Sir,
I read with interest the recent case of a 23-year-old nurse who presented with iron deficiency anaemia, as discussed in the Nephroquiz section of your journal [1].
I recently encountered a similar 28-year-old patient with 9 years of daily unremitting macroscopic haematuria of varying intensity. Renal function and blood pressure have remained normal throughout the disease course, but the patient developed microcytic, hypochromic anaemia over the years (haematocrit 32%, haemoglobin 10.3 g/dl, red blood cell count 4.37x103, and mean cell volume 73 µ3). Imaging studies, including an arteriogram, were normal at first presentation. A renal biopsy was performed and 14 glomeruli identified. Light microscopy showed a normal aspect of glomerular and tubular structures, insterstitium, and blood vessels. Immunofluorescence revealed four normal glomeruli with no deposits.
Electron microscopy showed a great variability in the width of the glomerular basement membrane (GBM) with segmental attenuation in the same capillary loop. GBM width oscillated between 134 and 365 nm. At different points, values of 160, 183, 228, and 286 nm were determined. In the same capillary loop next to the mesangial cells, isolated widenings of the GBM were observed while in other areas attenuation of the GBM was clearly visible. Podocyte foot processes were normal, as were endothelial cells. Taken together, these findings are indicative of thin-membrane nephropathy.
Although episodic gross haematuria has been reported in this condition previously, such episodes are very rare, and persistent and uninterrupted macroscopic haematuria has not been reported, to my knowledge. Hence, thin-membrane nephropathy should be included in the differential diagnosis of persistent macroscopic haematuria, particularly in young subjects.
References
Helios Klinikum Berlin, Franz Volhard Clinic, Medical Faculty Charité, Humboldt University of Berlin, Nephrology, Berlin, Germany Email: kettritz{at}fvk\|[hyphen]\|berlin.de
Sir,
Dr Vilches describes a patient similar to the young lady we presented in the Nephroquiz section. The patient developed microcytic, hypochromic anaemia and her biopsy was also consistent with thin-membrane disease, as the GBM showed areas of widening and thinning. Possibly, the presence of gross haematuria is not as rare as believed previously. In any event, we agree that the diagnosis should be considered in the differential diagnosis and further investigations, particularly in terms of possible genetic factors, should be vigorously pursued.