The red blood cell morphology of fresh urine is related to diseases of the urinary system and is of great value in identifying glomerular versus non-glomerular hematuria. However, the erythrocyte morphology of urine is also closely related to the acidity and osmolality of urine, therefore, attention must be paid to the differentiation.
(A) Red blood cell morphology
Since the late 1970s, the morphological classification of urine erythrocytes has been studied more using staining and non-staining methods, using phase contrast microscopy, dark field microscopy, etc.
1, normal erythrocytes: the morphology of unstained erythrocytes in urine is biconcave disc-shaped, light yellow, and about 8 um in diameter.
2, abnormal red blood cells: the common morphology of abnormal red blood cells in urine are.
① large red blood cells: red blood cells with a diameter > 8um.
②Small red blood cells: red blood cells with a diameter of <8um.
③Spiny erythrocytes: cytoplasm often protrudes and protrudes to one or more sides, such as raw bud-like.
④Ring-shaped erythrocytes (doughnut-shaped erythrocytes): due to intracellular hemoglobin loss or cytoplasmic aggregation, shaped like a doughnut-like hollow ring.
⑤ Crescent-shaped erythrocytes: erythrocytes like half-moon shaped.
⑥Granular-shaped erythrocytes: granular interrupted deposits in the cytoplasm with loss of hemoglobin.
(7) Crinkled erythrocytes: more common in high renal urine.
(viii) Shadow red blood cells: more common in low renal urine.
⑨ Red blood cell fragments.
(ii) Hematuria
The red blood cells in normal urine are very few and do not exceed 3/HPF. Microscopic red blood cells >3/HPF are called microscopic hematuria. When the naked eye sees different degrees of red turbidity such as washing water or blood clots, it is called hematuria of the naked eye, at this time, the amount of blood contained in each 1L of urine is more than 1ml.
According to the morphology of red blood cells in urine, hematuria can be divided into 3 types, namely homogeneous red blood cell urine (non-glomerular source hematuria), non-homogeneous red blood cell hematuria (glomerular hematuria) and mixed hematuria.
1. Homogeneous erythrocyte hematuria: The shape and size of red blood cells are mostly seen to be normal, and the morphology is more consistent, similar to the morphology of red blood cells on unstained blood films of peripheral blood. In a few cases, shadow red blood cells with lost hemoglobin or spiny red blood cells with slightly altered shape can be seen. No more than two erythrocyte morphologies are seen in the entire urine specimen. It has been reported that the diagnostic compliance rate of homogeneous red blood cells with renal biopsy is 92.6%.
2, non-homogeneous red blood cell hematuria: that is, deformed red blood cell hematuria, the size of red blood cells varies, the volume can vary 3-4 times, and more than 2 morphology of polymorphic changes of red blood cells can be seen in the urine, such as large red blood cells, small red blood cells, spiny red blood cells, crinkled red blood cells, etc. The diagnostic conformity rate of non-homogeneous red blood cell hematuria with renal biopsy can reach 96.6%.
3. Mixed hematuria: It refers to urine containing both homogeneous and non-homogeneous red blood cells. According to which type of red blood cells exceeds 50%, it can be divided into two groups, mainly homogeneous red blood cells and mainly non-homogeneous red blood cells.
In non-glomerular hematuria, the red blood cells in the urine are >8000/ml, but most of them (>70%) are normal red blood cells or monotypic red blood cells; in glomerular hematuria, the red blood cells in the urine are >8000/ml, and most of them (>70%) are more than 2 types of deformed red blood cells. There are still no uniform criteria for distinguishing non-renal and renal erythrocytic hematuria. Most believe that: non-glomerular hematuria, deformed red blood cells ≤ 50%, most of the red blood cells are normal red blood cells (or homogeneous red blood cells); glomerular hematuria, deformed red blood cells ≥ 80%.
Recently, new methods to distinguish non-glomerular and glomerular hematuria include.
①Echinocyte percentage method: that is, erythrocytes with one or more cytoplasmic protrusions of fried noodle circle-like erythrocytes ≥ 5% as a criterion for evaluating glomerular hematuria, which is considered to have 100% sensitivity and specificity.
②Red cell volume curve method: for renal glomerular hematuria, an asymmetric curve is presented, and the mean volume of urine red blood cells (MCV) is smaller than that of venous blood MCV; for non-glomerular hematuria, the red cell volume curve method presents a symmetric curve, and the MCV of urine red blood cells is larger than that of venous blood red blood cells; it is reported that if the MCV of urine red blood cells <72fl is used as a criterion for the diagnosis of glomerular hematuria, the specificity of the diagnosis is 100%.
(iii) Flow cytometry: a new test that measures anti-hemoglobin antibody or anti-Tamm-Horsfall protein antibody-stained red blood cells to identify the source of hematuria.
Methods
Non-glomerular hematuria
Glomerular hematuria
Urinalysis
Anisocytic red blood cells
-
+
G-1 cells
<5 %
>=5%
Cell tube type
-
+
Brown or tea-colored urine
+
++
Clear red
++
+
Clots
+
-
crystallization
+
-
Protein
-
+
Medical history
Family history of renal failure
-
+
with systemic lesions
-
+
Kidney stones
+
-
Trauma
+ – Trauma
-
Irritation symptoms
+
-
Clinical manifestations
Systemic indications
-
+
Hypertension
+
++
Edema
-
+
Abdominal masses
+
-
Urinary tract trauma
+
-
(iii) Mechanisms of morphological changes in hematuric red blood cells
The role of the glomerular basement membrane: It is currently believed that
① Non-nephrogenic hematuria: mainly bleeding from capillary rupture in the subglomerular area and urinary tract, red blood cells are not damaged by extrusion of the glomerular basement membrane and thus have normal morphology. Although the red blood cells from the renal tubules can also be affected by changes in acidity and osmotic pressure, they are homogeneous hematuria because of the short duration and slight changes.
(2) Glomerular hematuria: The mechanism of morphological changes in red blood cells may be due to extrusion damage when red blood cells pass through the pathologically altered glomerular basement membrane; and in the process of passing through each segment of the renal tubule, red blood cells are affected by different urinary acidity and changing osmotic pressure, together with the tension of the medium and the action of various metabolites (fatty acids, lysolecithin, bile acids, etc.), resulting in red blood cell size The changes in erythrocyte size, morphology and hemoglobin content.
When identifying urine red blood cell morphology, attention should also be paid to.
① The effect of urine osmolality and urine acidity on urine erythrocytes. In acidic urine, the volume of red blood cells becomes smaller; in alkaline urine, the red blood cells swell and easily dissolve and rupture with irregular edges; in hypotonic urine, the red blood cells become larger, swollen and easily ruptured, and due to the overflow of hemoglobin, the red blood cells become empty shadows of different sizes; in hypertonic urine, due to the concentration of urine, the red blood cells are crumpled and smaller, resembling star-shaped or mulberry-shaped.
② identify with fungal spore morphology, if necessary, can do the fragmentation test to identify: take the urine sediment, add 1% saponin solution 1 drop, mix, a few minutes after microscopic examination, such as red blood cells, the red blood cells are completely broken and disappeared, such as fungal spores, is still intact form. (③) closely combined with clinical: to make a reasonable diagnosis.
(iv) Clinical significance
The increase of red blood cells in urine is a sign of disease, while the identification of red blood cell morphology helps to determine whether hematuria is non-glomerular or glomerular disease.
1. Non-glomerular hematuria: seen in.
① Temporary microscopic hematuria, such as normal people, especially adolescents after strenuous exercise, rapid marching, cold bath, long standing or heavy physical labor. In female patients, attention should also be paid to the presence of menstrual blood contaminating the urine, which should be differentiated by dynamic observation.
②Urological system own diseases: such as inflammation, tumor, tuberculosis, stone, trauma, kidney transplant rejection, congenital malformation in various parts of the urinary system can cause different degrees of hematuria.
③ Other diseases: seen in bleeding diseases caused by various reasons, such as idiopathic thrombocytopenic purpura, hemophilia, aplastic anemia and leukemia combined with thrombocytopenia, DIC, hypertension, atherosclerosis, hyperthermia; certain immune diseases such as systemic lupus erythematosus; diseases of organs near the urinary system such as prostatitis, vesiculitis, pelvic inflammatory disease, etc. Non-nephrogenic hematuria is characterized by an increase in urinary red blood cells, while protein does not increase or does not increase significantly.
2, glomerular hematuria: seen in acute or chronic glomerulonephritis, pyelonephritis, lupus erythematosus nephritis, nephrotic syndrome. In nephrogenic hematuria, it is mostly accompanied by an increase in urine protein obviously, while the increase in red blood cells is not obvious. It is also often accompanied by tubular pattern, such as granular tubular pattern, red blood cell tubular pattern, tubular pattern of renal tubular epithelial cells, etc.