Diagnosis of Hematuria

Hematuria, with another name blood urine, is clinical divided to two types: microscopic hematuria and gross hematuria. Just as their name imply, microscopic hematuria refers to blood urine that need to be diagnosed with microscope and gross hematuria means blood urine that can be seen with the naked eye.

Hematuria is the presence of red blood cells in the urine. One the basis of origin of red blood cells in urine, hematuria can be classified into glomerular hematuria, nonglomerular hematuria and mixed hematuria. And the validity of differences between glomerular and nonglomerular erythrocytes and their clinical significance has been confirmed in a number of subsequent studies.

At present, the most common used method for distinguish glomerular and nonglomerular hematuria are phase-contrast urine microscopy and automated peripheral blood cell counter, through which we can know clearly whether hematuria occurs because of glomerular damages or others.

Through observing erythrocyte size, shape and hemoglobin pigmentation, we can find there are several different characteristics of glomerular and nonglomerular hematuria.

1. Compared with nonglomerular erythrocytes, glomerular erythrocytes are smaller. What is more, the red blood cells in glomerular hematuria vary greatly in both shape and size, whereas nonglomerular erythrocytes are uniform in size and shape.

In normal case, red blood cell can not go through glomerular filtration membrane. And when there is damages in membrane, only erythricytes with certain size are allowed to go through, but because of the small hole in membrane, shape of erythrocytes is changed. Generally speaking, in case of glomerular hematuria, more than 75% of red blood cells have their shape changed; however, in case of nonglomerular hematuria, less 50% of red blood cells have changed shape.

2. Glomerular erythrocytes look more pale than nonglomerular erythrocytes.

While going through glomerular filtration membrane, erythrocytes lose a large amount of their hemoglobin pigment easily, which makes their color light.

3. Glomerular hematuria is commonly accompanied by erythrophagocytes.

Lastly, in some cases, both misshapen red blood cells and normal red blood cell can be found. Under such a circumstance, mixes hematuria should be put into consideration.