Department of Neprhology University Hospital Nijmegen Nijmegem The Netherlands
Patients with haematuria are usually referred to the urologist. When the haematuria is isolated, without other signs or symptoms, one should first try to distinguish between a glomerular and a non-glomerular source in order to decide which further investigations will be necessary. Although gross haematuria is more frequently the presenting symptom in non-glomerular haematuria, this is by no means a one hundred percent reliable, diagnostic criterion, since haematuria of glomerular origin can also present as macroscopic haematuria. To make the distinction, an individual with sufficient expertise in this field should examine the urinary sediment. In the University Hospital of Nijmegen we have therefore made an arrangement with the urology clinic to avoid unnecessary urological examinations in patients with glomerular haematuria. When a patient with unexplained, microscopic or macroscopic haematuria is referred to the urologist, the nephrologist is asked to examine the urinary sediment before invasive examinations are undertaken.
Patient A, whose urinary sediment is shown in Figure 1, is a 56-year-old male who had macroscopic haematuria without other symptoms. Semiquantitative examination of the urine showed 3+ protein. You are the nephrologist who is asked to examine the urinary sediment and to give advice to the urologist which further actions have to be taken.
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The morphology of the erythrocytes in the urine can give information on the source of the bleeding [13]. Erythrocytes that have leaked through the glomerulus and have passed through the tubulus can become distorted during their passage along the nephron (dysmorphic or polymorphic erythrocytes). Erythrocytes originating from other sources in the urinary tract, for instance the bladder show much less signs of damage. They look more like the erythrocytes in the peripheral blood (isomorphic or monomorphic erythrocytes).
At first glance, the erythrocytes in Figure 1 look dysmorphic. On closer examination it appears, however, that there are only two types of erythrocytes present: normal erythrocytes and crenated cells. The extent of the crenation of the cells differs and this gives the false impression that they are dysmorphic. The inexperienced examiner often makes such a mistake. One should keep in mind that more than two different forms of erythrocytes have to be present to allow for a diagnosis of dysmorphic erythrocytes, suggestive of a glomerular origin of the haematuria. Figure 2
shows a different field in the same preparation where all erythrocytes are crenated. Here, the picture appears isomorphic which is consistent with a non-glomerular cause of the haematuria in this patient. Erythrocyte casts were not found on extensive screening. The proteinuria, that was also present, does not necessarily point to glomerular leakage of protein, but is commonly present in patients who have lost enough whole blood in their urine to cause gross haematuria. Your advice should be that a primarily urological investigation of the patient's haematuria is indicated.
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