Erythrocytes (hematuria)

Hematuria is defined as a high urine red blood cell count sustained over three specimens taken on different days. In a normal urine, less than 1,5 million erythrocytes are found in a 24-hour specimen. This normal value represents a count of less than 5 RBC/hpf. Hematuria is normally associated with a urinary tract disease. Some cases of idiopathic hematuria have been reported in the literature. Red blood cells originating from an external source, like vaginal bleeding, is not a true hematuria.
Two types of hematuria can be seen in urine

Lower urinary tract hematuria In the first type hematuria, the red cells have their typical shape and color. This hematuria is usually associated with a lower urinary tract disease.

Dysmorphic hematuria The second type of hematuria is called dysmorphic or renal hematuria. This hematuria is characterized by: a great variation in the size of the cells (anisocytosis), many ghost cells, and by a high percentage of dysmorphocytosis (>20%). This hematuria is usualy related with a glomerular bleeding. Dysmorphocytosis is characterized by bizarre shapes and projections of the cell membrane called blebs. Schramek has demonstrated that the dysmorphocytosis can be reproduced in vitro, by osmotic shocks in a hemolytic media. This situation compares well with the travel of a red blood cell from the glomerule to the bladder. In glomerulonephritis, the dysmorphic cells can represent up to 80% of the erythrocytes. A value of 14% was proposed by Pillsworth, as a cut-off value for the differentiation of renal from non-renal hematuria. At room temperature, the specimen is stable for up to 5 hours . It is not rare to see, in a sediment, what seems to be two populations of erythrocytes. This situation could correspond to a mixed hematuria. Recently, a glomerular-specific morphological alteration of red cells has been described, G1 cells or doughnut-shaped erythrocytes (acanthocyte) with one or more blebs are considered to be reliable markers for glomerular diseases. Tomita et al Nagama et al have futher refined the dysmorphocytosis concept. . Dysmorphic G1 cells called D cells are subdivised under three groups called D1, D2, and D3. D1 cells showed a ring-like shape and severe loss of cytoplasmic color with protrusions or blebs D2 cells showed a doughnut-like shape and moderate cytoplasmic color loss with protrusions or blebs D3 cells showed a doughnut-like shape and mild cytoplasmic color loss without protrusions or blebs. The sensitivity of D3 cells and D1 and/or D2 cells (G1 cells) was 73% and 46%, respectively, for the detection of glomerular diseases and the specificity was 93% and 99%, respectively D3 cell is a sensitive marker for glomerular diseases, and that D1 and/or D2 cells are markers for severe glomerular diseases.