The Kidney: From Normal Development to Congenital Disease

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This is a defect where the vertebrae in the lumbosacral area are not properly fused all the way around the spinal cord, and so a sac protrudes from the spinal cord with a mass of nerves all tangled together. In these nerves are those to the bladder, so that it has no functional nerve supply. The bladder then tends to fill and fill and only empty by overflow when it is quite full. There is often backpressure to the kidneys.

This can lead to vesicoureteral reflux explained later in this treatise and chronic infection and scarring of the kidneys, with eventual renal failure. Hydronephrosis without obstruction, including vesicoureteral reflux. Hydronephrosis without obstruction means dilatation of the ureter and collecting system of the kidney but not because of backup above an area of narrowing and obstruction, rather primary dilatation of the collecting system and ureter. The conditions causing this that I will discuss are: Prune belly syndrome occurs almost exclusively in boys; there is a controversy whether there is a variant in girls.

It consists of a group of findings including: Frequently the dilated ureters come with vesicoureteral reflux VUR; see below. The boys are sterile and unable to make sperm, even if the testicles are surgically brought down, but they function normally sexually. The bladder may be large and floppy and not contract and empty like it should, or it may be fine. High-grade reflux is common, but reimplantation of the ureters surgically into the large, floppy bladder may be difficult.

The Kidney: From Normal Development to Congenital Disease

With the renal dysplasia, renal failure may be a problem. The renal dysplasia may be of any degree of severity.

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Some of these boys progress to needing transplantation; others do not. In boys with prune belly syndrome the abdomen is protuberant because of the decreased or absent abdominal muscles and the lower part of the rib cage in front may flare out a little, causing an abnormal profile. The absence of the muscles of the abdomen causes surprisingly little functional problem. Some boys as they get older wear an elastic support garment around the abdomen to hold it in so that it looks better and clothes fit better. It also offers some protection to the abdominal organs.

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Vesicoureteral reflux VUR involves the two-way flow of the urine up and down the ureters, and they should be a one-way down system. The ureter inserts into the bladder down near its base such that the muscle of the bladder wall does not allow the urine to flow out of the bladder and back up the ureter towards the kidney. This insertion can be abnormal and allow different degrees of back flow, which are graded I to V, depending on severity. When grades I to III happen in an infant or young child, the likelihood is that with time and increasing maturity the problem will resolve itself.

Grade IV reflux occasionally spontaneously resolves, and grade V reflux virtually never resolves spontaneously. Grades IV and V usually need surgical correction. Megaureter and megacystis are two problems that often occur together.

The Kidney: From Normal Development to Congenital Disease - Google Books

Megaureter is the congenital dilatation of all or a portion of the ureter without obstruction. Megacystis means enlargement of the bladder, which may affect function in that the bladder may be slow to empty, and in some cases this may mean that intermittent catheterization is needed to empty the bladder. Both megaureter and megacystis are frequently associated with renal dysplasia. Most of the cystic diseases occur in both kidneys, but in the great majority of cases a multicystic dysplastic kidney is confined to one kidney.

In this disorder, the kidney is worthless and without any functioning filters and the ureter is atretic, meaning that it stops part way down to the bladder, so is incomplete. The "kidney", and I put it in parentheses since it is not really a kidney, as we know it, since something went awry very early in its development and it became a group of cysts rather than a kidney. A cyst is a fluid filled round bag-like structure. In most cases the other kidney is normal and grows larger than a normal kidney to make up for the fact that there is only one functioning kidney.

Two defects do occur in the functioning kidney with enough frequency to be of concern. The first is vesicoureteral reflux discussed previously in this article so every infant found to have a multicystic dysplastic kidney should have a VCUG, a voiding cystourethrogram to look for reflux.

The second is ureteropelvic junction obstruction, also discussed previously, which, if present, will have been noted on the ultrasound examination that was done to pick up the multicystic dysplastic kidney. A multicystic dysplastic kidney is often picked up on prenatal ultrasound, then confirmed on ultrasound after the baby is born. Since the bags of cysts can be confused with severe dilatation of the kidney related to a severe ureteropelvic junction obstruction, the doctor may want to look at the kidneys with a nuclear renal scan to differentiate between the two.

To do this scan, the infant is given an IV injection of a radioactive substance that shows blood flow into the kidney and is filtered by the kidney. The multicystic dysplastic kidney has no blood flow and no function, but the kidney with obstruction has blood flowing through it. The amount of radioactivity given is no more than one receives getting a standard X-ray. So the infant felt to have a multicystic dysplastic kidney generally has two tests done, a VCUG and a nuclear renal scan. If an associated problem such as reflux or UPJ obstruction is found, they are treated as noted above, with the need for treatment being related to the severity of the problem.

The multicystic dysplastic kidney itself is followed with serial ultrasound examinations at intervals over time. Most of the time when cystic kidney disease is mentioned, polycystic kidney disease PKD comes to mind. There are two types of polycystic kidney disease are: Let me give you a mini-genetics lesson to help explain the two diseases. Each of us has a set of genes from each parent, so we have a double of every gene.

In diseases where the trait is dominant, getting an abnormal gene from either parent gives you the disease. So in the typical case of a parent with a dominant disease, the parent got one normal gene from one parent who was healthy and an abnormal gene from a parent with the disease. So the child of that parent has a chance of getting the disease, depending on whether he got the diseased gene or the healthy one. Having one gene with the disease means you have the disease. In the case of parents of a child with a recessive disease, both parents have one normal and one abnormal gene, and the normal, rather than the abnormal gene, predominates.

A child of such parents has a one out of two chance of getting the abnormal gene from each parent, or a one out of four chance of getting an abnormal gene from both parents. Having both genes of the set abnormal gives the disease. So parents of the child with ARPKD are healthy and do not know that they carry the disease until they have a child with the disease.

A parent who has ADPKD knows that there is a chance, one out of two of each child born to that parent having the disease. ADPKD is a fairly common cause of kidney failure in adults. The cysts of the disease may be seen on a prenatal ultrasound of the developing fetus, but in most cases, the number of cysts in the kidneys increases slowly and kidney function is normal for most or all of childhood and into adulthood. The cysts can start to form in the kidneys in the fetus, or the kidneys may be normal without cysts until as late as 30 years of age.

At some age cysts start to form and more and more cysts progressively form in both kidneys. There is a tendency of the pattern of development of cysts to be the same in members of a family, but it is a tendency and not a rule.

As more and more cysts form often hypertension becomes a problem, and then after hypertension, gradual decrease in kidney function. The age at which kidney failure occurs and dialysis and transplantation are needed varies from infancy to old age. A few people die in old age with cysts in the kidneys but with the kidneys working well enough that they do not need dialysis or transplantation.

The average age of kidney failure is about 50 years old. ARPKD is a very uncommon disease. The baby with ARPKD has many small cysts all throughout the kidneys right from the time that they form in utero. The kidneys are larger than normal because of the cysts, sometimes very large.

In the most severely affected children the kidneys never work and never make urine. This leads to a lack of normal lung development, since lung development is dependent on breathing amniotic fluid, and amniotic fluid comes from baby urine. Without lung development the baby dies of lack of oxygen soon after birth.

In a few cases, fluid has been successfully injected into the uterus around the baby every few days for many weeks during pregnancy, resulting in lung development. This is tricky and may also result in stimulating labor, so that the baby is born quite prematurely with poor lung function and dies. Among the infants with the disease who survive, the severity of the kidney disease and the age at which dialysis and transplantation are needed varies between infancy and adolescence. Most children with ARPKD also have a condition known as congenital hepatic fibrosis, which means that there are threads of scar tissue through the liver.

This usually doesn't interfere with liver function but may obstruct the flow of blood to the liver through the portal vein from the intestines. This leads to back up of blood in the spleen and in veins of the esophagus and can cause serious problems, too. Backup of blood in the spleen means that platelets get trapped in the spleen and so are not in the general blood circulation.

Platelets are important in the circulation as agents of clotting. Meanwhile the blood in the veins of the esophagus is under increased pressure, so that the veins often burst and bleed. With low platelets, the esophagus may bleed and bleed if the veins burst. To prevent this kind of bleeding, some children with ARPKD need surgery to shunt blood flow away from the esophagus while those with a more severe form of hepatic fibrosis also need a liver transplant as well as a kidney transplant.

Another very rare form of bilateral renal cystic disease isglomerulocystic disease, where the cysts are in the glomeruli, the filters of the kidneys. This usually leads to kidney failure early in life. Other diseases which include bilateral both kidneys cystic kidney disease in addition to other health problems include: Metabolic diseases are those diseases where there is a chemical problem in certain or all cells of the body.

Most commonly they happen when an enzyme protein that breaks down a specific chemical is missing.

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That can result in the accumulation of that substance in cells, causing all sorts of problems. In some types of metabolic disease a substance accumulates in cells for unknown reasons. In others, an important cellular biochemical process is abnormal. Cystinosis is a rare disease where cysteine, an amino acid amino acids are the building blocks of proteins accumulates in the cells of the body and causes lots of problems, including kidney failure.

These children clearly are ill as infants, since they grow poorly, are easily and frequently dehydrated, and develop rickets. The problem with the kidneys early in life is that they leak multiple substances potassium, bicarbonate, sodium, phosphorus, glucose and amino acids from the blood into the urine that should stay in the blood. Don't have an account? Your Web browser is not enabled for JavaScript.

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In recent years advances in molecular techniques have not only made great inroads into exploring the genetic regulation of this complex process but also began to unravel the molecular basis of many forms of congenital kidney disease. This book is a comprehensive study on these findings and the only book available with such in depth coverage of the kidney. Allow this favorite library to be seen by others Keep this favorite library private. Find a copy in the library Finding libraries that hold this item Electronic books Additional Physical Format: Document, Internet resource Document Type: Organogenesis of the kidney has been intensely studied.

Advances in molecular techniques have not only made great inroads into exploring the genetic regulation of this complex process but also began to unravel the molecular basis of many forms of congenital kidney disease. This book presents a study on these findings. Publisher Synopsis "well organized and well written User-contributed reviews Add a review and share your thoughts with other readers.

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