About urinary erythrocyte dysmorphism

Massimo Gai, Giorgina B. Piccoli, Alberto Jeantet, Giuseppe P. Segoloni and Giacomo Lanfranco

Chair of Nephrology, University of Torino, A.S.O. San Giovanni Battista di Torino, Italy Email: massimogai{at}katamail.com

Sir,

In the last few years many laboratories have been making efforts to standardize methods of handling and analysing urinary sediments [1]. Some questions remain open, however, and are as yet unsolved, creating a source of discussion.

First, we think that it is necessary to standardize the terminology used to interpret urinary sediment analysis. Terms such as ‘glomerular haematuria’ and ‘non-glomerular haematuria’ should be replaced with ‘renal haematuria’ and ‘post-renal haematuria’, since mechanical damage to the glomerular basement membrane and osmotic injury in tubules may cause red blood cell deformity [24].

A second point concerns the terms ‘dysmorphic’ and ‘isomorphic’ erythrocytes, which would be better defined as ‘dysmorphic’ and ‘normal’ erythrocytes. In fact, the term ‘isomorphic’ may cause confusion and allow different interpretation in different laboratories [5]. In this regard, if the main forms of dysmorphic erythrocytes have been well classified and universally recognized (Figure 1Go), a more accurate definition is called for, in which erythrocytes should surely be considered ‘normal’, even if deformed [6,7] (Figure 2Go). Further studies are therefore needed to clarify whether erythrocyte size is a useful criterion for evaluation of cell dysmorphism.



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Fig. 1.  Dysmorphic haematuria: phase contrast microscopy showing a typical acanthocyte with vesicle-shaped protrusions (arrow). Magnification: x400.

 


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Fig. 2.  Renal bleeding. Phase contrast microscopy showing dysmorphic (A) and normal (B) erythrocytes. Magnification: x400.

 
There remains an issue regarding the uncertainty of the percentage of dysmorphism for the diagnosis of renal haematuria, which varies in the international literature from 40% to 80% [8].

References

  1. ECLM–European urinalysis group. European urinalysis guidelines. Scand J Clin Lab Invest2000; 60: 1–96[Medline]
  2. Lettgen B, Wohlmuth A. Validity of G1 cells in the differentiation between glomerular and non-glomerular haematuria in children. Pediatr Nephrol1995; 9: 435–437[ISI][Medline]
  3. Lye WC, Leong SO, Lee EJC. Rhabdomyolysis with acute tubular necrosis—a nonglomerular cause of dysmorphic hematuria. N Engl J Med1992; 327: 570–571[ISI][Medline]
  4. Serra A, Torguet P, Romero R, Bonal J, Caralps A. Normal urinary red blood cell morphology in segmental necrotizing glomerulonephritis. Nephron1991; 59: 351–352[ISI][Medline]
  5. Rath B, Turner C, Hartley B, Chantler C. What makes red cells dysmorphic in glomerular haematuria? Pediatr Nephrol1992; 6: 424–427[ISI][Medline]
  6. Kohler H, Wandel E, Brunck B. Acanthocyturia—A characteristic marker for glomerular bleeding. Kidney Int1991; 40: 115–120[ISI][Medline]
  7. Kitamoto Y, Tomita M, Akamine M et al. Differentiation of hematuria using a uniquely shaped red cell. Nephron1993; 64: 32–36[ISI][Medline]
  8. Dinda AK, Saxena S, Guleria S et al. Diagnosis of glomerular haematuria: role of dysmorphic red cell, G1 cell and bright-field microscopy. Scand J Clin Lab Invest1997; 57: 203–208[ISI][Medline]




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