How Is Polycystic Kidney Disease Caused?

Causes of polycystic kidney disease

The cause of polycystic kidney disease is a genetic deletion. Among them, adult polycystic kidney disease is often caused by the gene deletion of chromosome 16 and occasionally caused by the gene deletion of chromosome 4, which is a dominant inheritance with a penetrance rate of 100%. Therefore, the chromosomal deletion of a single parent will make its children 50%. possibility of inheriting the disease. Infantile polycystic kidney disease is an autosomal recessive inheritance. Both parents have the genetic change of the disease to make their children develop the disease. The incidence rate is 25%.

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There is evidence that the disease is related to heredity. Bucket al. reported a family of 8 siblings, 6 of whom had kidney cysts, their father and uncle also died of uremia, and 5 of their next-generation had kidney disease; Bracket al. Et was reported that polycystic kidney disease was found in all 4 generations of one family; Reason et al. reported that all twins suffered from the disease; Crawford reported that polycystic kidney disease was found in 17 people in a family of 40 people.

70% to 90% of the disease is bilateral. Among the 62 cases reported by Lejars, only 3 cases were unilateral; Dickinson reported that the ratio of unilateral to bilateral was 1∶26; the volume of the polycystic kidney was seen in gross specimen examination It is more than 2 to 3 times larger than the normal kidney. It has been reported that a case of bilateral polycystic kidney weighed 14436g, and Schacht reported that a cystic kidney weighed 7248g. The appearance of polycystic kidneys is mostly irregular cystic nodules, and there are numerous cysts of varying sizes in the shape of a honeycomb on the cut surface.

The cystic cavity of infantile type (Potter type I) polycystic kidney is the size of a pinhead, and there is very little kidney tissue between the cysts. When the cyst enlarges, the kidney parenchyma shrinks due to being compressed, so the medulla and cortex are underdeveloped, and the cystic cavity is not fully developed. It contains yellow-brown mucous, purulent or blood-like fluid, etc., and there is no communication between the cyst and the kidney pelvis; the normal kidney tissue between the adult-type cysts is extremely rich, and it can communicate with the kidney pelvis (the adult type is Potter III). Kasper et al. have reported that Potter type II polycystic kidney disease is mostly in the left kidney and generally has no clinical symptoms. It may also have kidney pelvis and ureter obstruction or atresia, while the other two types of kidney pelvis and ureter are often narrowed due to compression, but not obstructed. The arterial branches between the lobules also have signs of significant compression. The cyst wall is composed of cuboidal epithelial cells with secretory functions. There are many small arteries under it. These blood vessels can cause hematuria due to increased pressure and rupture.

Pathogenesis of polycystic kidney disease

The pathogenesis of this disease is unknown. Hilde-brand et al believed that polycystic kidneys may be formed by the expansion of Bowman's capsule, or by the expansion of kidney convoluted tubules, which are developed from the glomeruli, kidney convoluted tubules, and Wolffian ducts developed from the metanephric embryo. Communication between the collecting ducts is impaired; Bialestack suggests that some cysts are abnormally enlarged nephrons called meganephrons. It is also believed that some cysts have an excretory function; Bricker et al. carried out a chemical analysis of the fluid in the cyst and proved that the composition contained in the cyst was similar to that of urine; Norris et al. believed that because many temporary metanephroi could not atrophy normally, some nephrons occurred. Local constriction and segmentation, resulting in the formation of cysts of different sizes; Hepler et al believed that the abnormal distribution of blood circulation in the kidney resulted in the degeneration of the kidney parenchyma; Hidd-brant believed that the secretory part (the kidney convoluted tubule derived from the kidney tissue) and part of the glomerulus) and the excretory part (collecting duct, kidney pelvis, etc. from the ureteral bud) lose contact with each other during the developmental period, the secretory part becomes a blind end, and its secretions cannot be discharged, so most cysts are formed; Sexual factors such as local inflammation in the fetal period cause fibrous obstruction of the excretory duct, or due to the blockage of casts and insoluble calcium salts, the result of poor urine flow and kidney tubule enlargement.

There are two theories that can explain some clinical phenomena:

1. Lambert studied in detail the cystic kidneys of infants and adults through serial sections of the kidneys and pointed out that polycystic kidney cysts have three types and origins: ① glomerular cysts; ② kidney tubular cysts; ③ excretory duct cysts. The cyst wall is lined with cuboidal or flat cells, the interstitium is rich in fibrous connective tissue, the medulla and cortex are hypoplastic, and most of the normal nephrons disappear; he found that all cysts connected to the kidney tubules in the cystic kidney of the infant were associated with The functional convoluted tubules are not connected, and the nephrons with cysts have no function; in the adult diseased kidney, in addition to the above types of cysts, some cysts grow on their own functional kidney tubules and kidney pelvis, and normal kidneys between cysts. The tissue is extremely rich and has functional activities, so there may be no clinical symptoms in the early stage, and even when the adjacent kidney tissue is compressed and atrophied, the function can be maintained until the cyst continues to grow, and when compressive kidney atrophy occurs, the kidney function declines and died, but there is still no proper explanation for the cause.

2. Dammin believes that the glandular system has too many glandular epithelial cells formed during normal embryonic development, and in the continuing development stage, glandular epithelial cells generally degenerate, digest, and disappear, and the initial stage of degeneration is to complete the division of epithelial ducts. If the segment is isolated and not retracted, the cyst will form, that is, the segmental expansion formed at the proximal end of the kidney tubule in the kidney cyst, which is still in communication with the filtrate of the glomerulus. The theory that cannot be connected is contrary and can explain the phenomenon that polycystic kidneys can have multiple cystic diseases of the liver, spleen, pancreas, and even ovary, uterus, and bladder.

The disease is usually bilateral kidney involvement, rarely unilateral involvement. A normal adult kidney weighs about 150g. In asymptomatic adult patients with polycystic kidney disease, the average weight of a single polycystic kidney is 256 g; in symptomatic adult patients with polycystic kidney disease, the average weight of a single polycystic kidney is 465 g. In adult polycystic kidney disease, diffuse cysts are common in the kidneys, and both the kidney cortex and medulla are covered with cysts of varying sizes, resembling a bunch of grapes. Cyst wall epithelial cells have limited proliferation, forming polypoid, abnormal proliferation of extracellular matrix, cyst formed by bulging of the proximal tubule, cyst fluid composition similar to plasma; cyst formed by distal tubule, the content of sodium and chloride in cyst fluid is low, while the urea and creatinine concentrations were higher. In patients with symptomatic polycystic kidney disease, with the increase of age, the number of cysts increases, and the cyst cavity enlarges, with a diameter of 2 to 3 cm. Common cysts >3cm in diameter often contain bloody fluid or blood clots.

Sections of the polycystic kidney showed that the cysts were uniformly distributed in the cortex and medulla, and the kidney pelvis and calyces were often significantly deformed. In severe cases, there is little visible residual kidney tissue. However, in patients with mild symptoms, the disease is often confused with multiple simple cysts (such as simple kidney cysts, and solitary multilocular cysts).

Microscopic observation showed that normal kidney tissue was compressed by adjacent cysts, and glomerulosclerosis, tubular atrophy, and interstitial fibrosis were secondary to vascular sclerosis or pyelonephritis. Identification of the tissue source of a cyst is difficult unless the cyst retains the normal location of the original tissue and morphological features of the epithelium. Cysts from the kidney capsule sometimes contain deformed small looped glomerular vascular plexuses; cysts from the deep collecting system are often thin-walled; cysts from the subcapsular collecting system have thicker walls and are often surrounded by dense fibers connective tissue. Specific lectin binding assays can be used to help identify the cyst's tissue source as proximal tubules, collecting ducts, or others.

Cistanche is the best herb for polycystic kidney

Cistanche is the most commonly prescribed herb in traditional Chinese medicine to prevent, relieve and even treat kidney disease. Modern medical research has also shown that many compounds in Cistanche have a good curative effect on kidney disease. Including, kidney damage caused by acute kidney disease, chronic kidney disease, nephritis, kidney failure, polycystic kidney disease, etc., The main active ingredients in Cistanche are phenylethanoid glycosides, echinacoside, acteoside, and flavonoids. Taking cistanche can increase the proliferation of kidney cells by 8-10 times.

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