In case of kidney diseases, protein accumulates in the renal tubules, leukocytes, erythrocytes, exfoliated epithelial cells and other particles “stick” to it. This plastic mass envelops the tubules, cylindrical in shape, from the inside, and thus makes, as it were, their cast. When urinating, these cylindrical casts are washed out and determined by the laboratory assistant during analysis.
Since protein and other elements are excreted in the urine only in a pathological condition of the kidneys, then in a healthy person there should be no cylinders in the sample, only hyaline cylinders and no more than 1-2 in the field of view, an increased content of this species or the presence of others (granular , waxy, erythrocyte, leukocyte, epithelial) is possible only with various renal diseases.