Symptom >> Internal Medicine >> Urology

Cast proteinuria

Introduction
Cause
Examine
Diagnosis

Introduction

Introduction Tubular urine is a kind of cylinder formed by the aggregation of proteins in the renal tubules. Normal people should have less than 5,000 urinary tube types in 12 hours, 2 to 5 in each milliliter of urine, or less than 1 in each low-power field. There may be a small amount of transparent and cell granules in the urine of normal people. If there is an increase in the type of tube in the urine, it is called tube type urine.

Cause

Cause

Protein secreted by renal tubular epithelial cells forms a transparent cast due to concentration and coagulation in an acidic environment. If accompanied by red and white blood cell agglomeration, it is called cell tube type. If there is degenerative cell debris, a granular cast is formed. A fat tube type is formed if the tubular matrix contains fat droplets or is embedded in epithelial cells containing fatty degeneration.

The tube type is an important component in urine sediment, and its appearance often indicates substantial damage to the kidney. It is a cylindrical structure formed by solidification of proteins in the urine in the renal tubules and collecting ducts. The formation of the casts requires proteinuria, and the matrix formed is a TH glycoprotein. In 1966, Mcqueen further confirmed by fluorescent antibody method that various proteins of different molecular weights in plasma can be aggregated in a transparent tubular matrix (TH glycoprotein) in the form of particles. In the pathological condition, due to the increased permeability of the glomerular basement membrane, a large amount of protein enters the renal tubule from the glomerulus, and in the renal distal convoluted tubule and collecting duct, acidification (increased acidity) and cartilage due to concentration (water absorption) In the presence of sulphate, the protein condenses and precipitates in the renal tubules to form a cast.

Examine

an examination

Related inspection

Urine sediment urine routine

Increased granules in the urine often indicate damage to the renal parenchyma. In patients with chronic renal failure, large and long granular casts are found in the urine, and the prognosis is better with the combination of traditional Chinese medicine and western medicine.

The clinical significance of various tube types is as follows:

(1) Cellular type: 1 The red blood cell cast is pathological, indicating that the source of hematuria is in the renal tubule or glomerulus, which is common in acute glomerulonephritis, acute pyelonephritis or acute renal failure. 2 white blood cell cast is pathological, is an important evidence for the diagnosis of pyelonephritis and interstitial nephritis. If there are more such tube types in the urine, it has more diagnostic value and can be used as a basis for distinguishing pyelonephritis and lower urinary tract infection. 3 Epithelial cell casts appear in large amounts in the urine, indicating that the renal tubules have active lesions. This condition can occur in glomerulonephritis, often coexisting with granules, clear or red, and white blood cell casts.

(2) Granular tube type: The granular tube type is derived from the epithelial cell cast type or formed by the protoplasmic adhesion of the disintegrated epithelial cells. The granular tube type means that there is degeneration and necrosis of renal tubular epithelial cells at the same time as proteinuria, which is more common in various glomerular diseases and toxic damage of renal tubules. Sometimes it can also occur in normal human urine, especially after strenuous exercise, if it is repeated frequently, it is abnormal.

(3) Wax-like and fat-tube type: wax-like and fat-tube type are formed after the cell granules are degraded again, often reflecting the atrophy and expansion of the renal tubules. More common in chronic kidney disease with reduced urine output, or in the presence of fatty disease in nephrotic syndrome.

(4) Transparent tube type: The transparent tube type can appear in normal urine, and the transparent tube type will increase when there is proteinuria, which is found in various glomerular diseases.

Diagnosis

Differential diagnosis

In some cases cells or particles tend to pile up together, similar to a tube shape. It is characterized by short length, wide and narrow width, and irregular edges.

(1) Red cell cast (red cell cast): The red blood cells are the main body of the tube type, and the appearance is slightly yellowish brown. It can be seen that the red blood cells are intact, clear or abnormal, and easy to identify. But sometimes red blood cells often stick to each other without obvious boundaries, sometimes even incomplete, and morphologically intact red blood cells can be seen at the edge of the tubular shape; sometimes only red blood cell light shadows or broken red blood cells can be seen due to hemolysis. If the tube type stays in the renal tubule for a long time, the red blood cells in the tube type can be broken into granular samples to form a granular tube type, and blood tube type and hemoglobin tube type can also be formed by hemolysis or homogenization.

S staining: the tubular matrix was stained light blue, the red blood cells in the tubular form were stained red to red; SM staining: the tubular matrix was stained light red, and the red blood cells in the tubular type were stained red to purple.

(2) white cell cast (white cell cast): tubular contents are mainly white blood cells, sometimes containing degeneration and necrosis of white blood cells (or pus cells), usually mostly neutrophils. The white blood cells in the tube type are mostly round, sometimes clustered and overlap each other; the white blood cells in the tube type are sometimes broken due to destruction. Under ordinary light microscopy, non-stained specimens are sometimes confused with renal tubular epithelial cells, making it difficult to identify. The nucleus can be displayed by adding dilute acid. The neutrophils are mostly lobular nucleus, while the renal tubular epithelial cells are generally a large round nucleus; after oxidase staining, neutrophils are positive, renal tubular epithelium The cells were negative. The staining method can more closely observe the morphology and characteristics of the nucleus and cytoplasm, which is easier to identify. When the leukocyte tube type stays in the kidney for too long, it will disintegrate and break down, forming a coarse-grained tube type and a fine-grained tube type, which can be changed into a wax-like tube type after homogenization.

S staining: the tubular matrix was stained light blue, the neutrophil nucleus in the cast tube was lobulated, the lymphocytes were mononuclear, stained dark blue, the cytoplasm of leukocytes stained reddish-red; SM stained: tubular matrix Dye reddish, the cytoplasm of leukocytes in the tube type is colorless-light blue, and the nuclear stain is purple-blue.

(3) renal epithelial cell cast (renal epithelial cast): also known as renal epithelial cell cast. Since the cast is formed in the renal tubule, the contained epithelial cells are tubular epithelial cells that fall off the renal tubular wall. It can be divided into two categories: one is composed of exfoliated renal tubular epithelial cells and TH protein, the epithelial cells are separated from the basement membrane, and the exfoliated renal tubular epithelial cells are stuck together; the other is acute tubular necrosis. At the time, the cell body is large and variable, and the typical epithelial cells are arranged in a tile shape, filled with tube type, the cell size is different, the nucleus is blurred, and sometimes the light yellow color. This type of tube is often difficult to distinguish from leukocyte tube type, but the tubular type of tubular epithelial cells are slightly larger than white blood cells, which can be polygonal, and the morphological changes are more complex than white blood cells. They contain a large cell nucleus, and the nucleus can be presented by acid addition. Esterase staining was positive and peroxidase staining was negative, which allowed differentiation with leukocyte casts.

(4) Composite cell tube type: If the tube type contains more than two kinds of cells at the same time, it can be called a composite cell tube type, and the various cells overlap and overlap each other, and the edge boundaries are blurred, especially in unstained, ordinary light. Under the mirror condition, it cannot be accurately identified, and can be collectively referred to as a cell tube type.