Correspondence

Diagnostic Value of Dysmorphic Urinary Red Cells

N Engl J Med 1996; 335:1323October 24, 1996

Article

To the Editor:

Dr. Saad's photomicrographs of dysmorphic urinary erythrocytes (Images in Clinical Medicine, May 30 issue),1 although beautiful, are dangerously misleading. Dysmorphic cells do not represent glomerular bleeding, as the legend implies. They can be produced as a result of kidney biopsies2 and are therefore not necessarily of glomerular origin. Renal tumors can also be expected to produce dysmorphic hematuria. By assuming that a finding of dysmorphic red cells rules out all causes of hematuria other than glomerulonephritis, one could miss a renal tumor.

Akos Z. Györy, M.D., D.Sc.
Sydney University, Sydney, NSW 2006, Australia

2 References

1. 1

   Saad TF. Dysmorphic urinary erythrocytes. N Engl J Med 1996;334:1440-1440
   Full Text | Web of Science | Medline

2. 2

   Pollock C, Pei-Ling L, Gyory AZ, et al. Dysmorphism of urinary red blood cells -- value in diagnosis. Kidney Int 1989;36:1045-1049
   CrossRef | Web of Science | Medline

Author/Editor Response

Dr. Saad replies:

To the Editor: Dr. Györy correctly notes that dysmorphic urinary erythrocytes may have a nonglomerular origin. A wide variety of abnormal-appearing erythrocytes can be seen in the urine, most of them nonspecific with regard to origin. My photomicrographs show erythrocytes with discrete spheroidal protrusions, a morphologic abnormality highly specific for hematuria of glomerular origin.1,2 These cells were classified as acanthocytes by Köhler et al.1 with phase-contrast microscopy in a study of 351 patients with hematuria. When cells of this type made up more than 5 percent of urinary erythrocytes, the sensitivity and specificity for glomerular disease were 52 percent and 98 percent, respectively. By contrast, red-cell casts had 24 percent sensitivity and 97 percent specificity for glomerular disease. Two patients with tumor-associated hematuria had urinary acanthocytes whose proportion exceeded 5 percent, but glomerular disease could not be ruled out, because these patients did not undergo kidney biopsy. No other type of dysmorphic erythrocyte was useful in determining the source of the hematuria. Tomita et al.2 conducted a similar study with interference contrast microscopy. When intact and ghost forms of “doughnut-like cells with one or more blebs” made up more than 1 percent of urinary erythrocytes, the sensitivity and specificity for glomerular disease were 89 percent and 95 percent, respectively. Interference contrast microscopy may improve the sensitivity of these cells in the diagnosis of glomerulonephritis, but they are easily seen with the ordinary bright-field microscopy available to most physicians.

Theodore F. Saad, M.D.
University of Texas Health Science Center at San Antonio, San Antonio, TX 78284

2 References

1. 1

   Kohler H, Wandel E, Brunck B. Acanthocyturia -- a characteristic marker for glomerular bleeding. Kidney Int 1991;40:115-120
   CrossRef | Web of Science | Medline

2. 2

   Tomita M, Kitamoto Y, Nakayama M, Sato T. A new morphological classification of urinary erythrocytes for differential diagnosis of glomerular hematuria. Clin Nephrol 1992;37:84-89
   Web of Science | Medline

Citing Articles (1)

Citing Articles

1. 1

   Kore, Dow, Desai. (1999) A new automated system for urine analysis: a simple, cost-effective and reliable method for distinguishing between glomerular and nonglomerular sources of haematuria. BJU International 84:4, 454-460
   CrossRef