Kidney (Renal) Dysplasia and Cystic Disease
Most kidneys work efficiently in cleaning the blood of its impurities while keeping the body in balance. But some conditions, often present at birth, do incredible damage to this sophisticated filtering system. What are renal dysplasia and cystic diseases and can they be cured? The following information will help you talk to your urologist when your condition, or that of your child, belongs to this family of diseases.
What happens under normal conditions?
The kidneys are fist-sized organs responsible for the fluid and acid-base balances of your body. Located on either side of the spine behind the liver, stomach, pancreas and intestines, these two organs are protected by the lower ribs and muscles of the back and sides.
When healthy, your kidneys cleanse the blood of waste products by producing urine. They also balance essential elements, such as sodium and potassium, while providing hormones necessary to regulate blood pressure and red blood cell production.
What are the symptoms of renal dysplasia and cystic disease?
Many conditions linked to renal dysplasia and cystic disease cause no problems at all. But for those that do, discovering the precise cause requires varied steps. For instance, congenital problems may be identified during pregnancy, leading to further evaluation following birth. Other cystic diseases can be found when imaging tests are performed for another problem. They are identified because of symptoms — pain, blood in the urine (hematuria), high blood pressure (hypertension) or urinary tract infections.
What are the different types of renal conditions and diseases?
Renal agenesis: Most people are born with two kidneys. But one in 4,000 infants (more boys than girls) come into the world with only one organ, the characteristic signal of renal agenesis. It is frequently identified because of pregnancy screening, often to evaluate another problem. On occasion, imaging tests will pick up a very small kidney, located in an abnormal position. Your physician may recommend another special imaging test on your infant to determine whether there is a small amount of kidney tissue missed by the initial study.
Renal dysplasia: An abnormal tissue development in the kidney that can be confined to a small portion of one (unilateral) or both (bilateral) kidneys arranged in a specific pattern within the kidney or randomly present throughout one or both kidneys.
Renal hypoplasia: Small kidneys which are otherwise normal. This condition may involve one or both sides. Renal hypoplasia does not appear to be an inherited condition nor does it occur more often in boys than girls. In fact, while the true incidence is unknown, it has been reported in as high as 2.5 percent of the population. The size of the kidney determines potential problems in the future. If a child's kidneys are extremely small, their function may decrease as the child enters their teens. Although a rarity, kidney failure may occur which would require supportive measures.
Renal hyposplasia may also be associated with abnormalities of the ureter, the tube that connects the kidney to the bladder. This condition is marked by either a backflow of urine from the bladder into the kidney or an obstruction of the ureter at the juncture where it abnormally enters the kidney.
Autosomal recessive polycystic kidney disease (ARPK): Most commonly noted in infants, ARPK also has been described as "infantile polycystic kidney disease." It occurs in one in 5,000 to one in 40,000 births, even though the condition may also first appear during adolescence or young adulthood. There is a spectrum of severity with this disease, appearing at an early age, progressing to variable degrees of kidney failure. ARPK is also linked to fibrosis, an abnormal overgrowth of connective tissue, in the liver.
ARPK in a fetus is often identified during a fetal sonogram at the time of pregnancy. The urologist bases a diagnosis on kidneys that are misshaped and considerably larger than normal. At birth, you can expect symptoms such as abdominal lumps on both sides and/or kidney failure. While kidneys vary in size, the characteristic cysts of this disorder are very small and are spread randomly throughout the kidneys.
Autosomal dominant polycystic kidney disease (ADPK): ADPK is one of the most common causes of kidney failure, present in 10 percent of patients on hemodialysis. The incidence rate is one in 500 to one in 1,000, with approximately 500,000 Americans suffering from a condition that results in an enlarged cyst-filled kidney. Previously identified as "adult polycystic kidney disease," most patients are diagnosed between ages 30 and 50 but the disease can appear in all age groups. Because of the disease, 50 percent of children born to individuals with this disease will also inherit it.
In terms of symptoms, infants usually experience serious kidney failure and respiratory problems. Children older than age one have high blood pressure or enlarged kidneys. If you are an adult, you may experience visible or microscopic blood (hematuria) in your urine along with flank pain, high blood pressure or occasional gastrointestinal symptoms, due to enlarged kidneys or associated colonic diverticula. Both kidneys will have varying-sized cysts, which may also appear in the liver. Approximately 10 to 40 percent of individuals also experience an abnormality of the blood vessels in the brain, which can lead to sudden bleeding and risk of aneurysm. While ADPK can be debilitating, the good news is that the risk of a kidney tumor is no greater with this disease than the risk in the general population.
Juvenile nephronophthisis and medullary cystic disease complex: Occurring in one in 50,000 to one in 100,000 births, juvenile nephronophthisis is found in 10 to 20 percent of children with kidney failure. Sufferers of this rare condition complain of great thirst and urinate excessively. They may also have eye problems, skeletal abnormalities and liver fibrosis. Less than half of those diagnosed as children have cysts on their kidneys. Kidney failure usually occurs in the early teens as part of juvenile nephronophthisis. With medullary cystic disease, kidney failure usually occurs in adults between the ages of 20 to 40. Symptoms of the latter condition include cysts of varying size, usually less than one centimeter.
Renal cystic disease syndromes: Renal cystic disease is common in individuals with a variety of other serious maladies. For instance:
Tuberous sclerosis (TS): Consisting of three characteristic components — epilepsy, mental retardation and fleshy nodules beneath the skin — tuberous sclerosis occurs in one in 9,000 to one in 70,000 newborns. Renal cysts develop in 20 percent of individuals, most often in childhood. The incidence of kidney tumors is greater in patients with tuberous sclerosis than in the normal population.
Von Hippel-Lindau disease: An inherited condition that occurs in 50 percent of children with an affected parent. Manifested by blood vessel abnormalities of the brain and eye, this disease also produces cysts of the pancreas, kidney and epididymis. With this condition, benign fatty tumors are interspersed between the cysts. Tumors of the adrenal gland (pheochromocytoma) are also present. While renal cysts occur in approximately 80 percent of patients with Von Hippel-Lindau disease, kidney cancer is present in just under 40 percent of individuals. The cysts and tumors usually do not produce symptoms unless they become very large, triggering pain or bleeding due to ruptures.
Multicystic dysplastic kidney (MCDK): The most common type of pediatric renal cystic disease, MCDK is also the most common abdominal mass, which can be felt as a lump in an infant. MCDK is often identified during a fetal sonogram at the time of pregnancy. On sonography, the kidney appears like a bunch of grapes with very little kidney tissue, rather than an organ with normal contours. The kidney usually has no function. In 10 percent of sufferers, an obstruction at the ureteropelvic junction may occur in the opposite organ; in 20 percent of cases, there is also abnormal urine backflow from the bladder into the ureter. When MCDK occurs on both sides, the result is a spontaneous abortion of the fetus. High blood pressure and renal tumors may be associated with this condition in children, but are exceedingly rare.
Simple renal cyst: Simple renal cysts occur in approximately one in 500 individuals between birth and age 18, appearing similarly in both genders. (Autopsy reports have shown the incidence to be approximately 50 percent at age 50.) Most simple cysts do not cause problems but are usually found when an individual is undergoing tests for other problems. Large renal cysts may produce abdominal pain, blood in the urine (hematuria) or, in rare incidents, high blood pressure. Simple renal cysts are not associated with kidney cancer. But the risk of malignancy increases if the cyst is identified as complex (with multiple chambers or irregularities in the wall) and/or contains calcium.
Medullary sponge kidney: Characterized by multiple, small cysts in the tubules that collect urine, medullary sponge kidney is estimated to be present in one of 5,000 to one of 20,000 individuals. Patients may exhibit kidney pain, blood in the urine and/or higher calcium output in their urine.
Acquired renal cystic disease: Acquired renal cystic disease occurs in individuals who have long-standing renal failure, particularly those undergoing dialysis. The risk of kidney cancer is significantly increased with this disease. Patients usually complain of back pain or blood in the urine.
How are these different types of renal conditions and diseases treated?
Renal agenesis: There is no specific treatment for renal agenesis. Dietary precautions are likely to have a limited influence on the remaining single kidney and are not practical to be maintained long term. Restriction in contact sports is recommended, along with avoiding activity that places the individual at substantial risk due to injury (e.g., motorcycle riding, all-terrain vehicles and trampolines). Your doctor should discuss with you appropriate restrictions and limitations.
Renal hypoplasia: There is no treatment for renal hypoplasia. Any associated ureteral problems should be treated to reduce the risk of infection and rapid decrease in kidney function. Unfortunately, this will not reverse the process of hypoplasia. Therapy consists of maintaining fluid and electrolyte balance and correcting abnormal acidity levels in the blood.
Autosomal recessive polycystic kidney disease (ARPK): There is no cure for ARPK. Treatment for this childhood illness focuses on supportive measures — such as dialysis — for kidney failure. If the organs are enlarged, some children benefit from removing them, especially if the size is causing difficulty with breathing, feeding or peritoneal dialysis.
Autosomal dominant polycystic kidney disease (ADPK): Since there is also no cure for ADPK, treatment centers on controlling symptoms. Approximately 60 percent of patients with this disease have high blood pressure that, if left untreated, can lead to heart disease and brain hemorrhages or stroke. More than half of these patients will have pain that can be very intense, occur suddenly and persist for a long time. Pain can be due to the presence of stones, blood clots or infection. Also, individuals (particularly women) with ADPK are at high risk for urinary tract infections. But treating these infections can be difficult, given the limited concentration of antibiotics within the cyst fluid.
When such an infection does not respond to medication, your doctor may recommend draining the cyst by needle aspiration, laparoscopy or an open surgical procedure. While draining the cysts connected to this disease can be beneficial, the fluid is likely to accumulate again. In any case, you will be followed closely over time since the disease is progressive and renal failure can occur, which will require supportive measures.
Juvenile nephronophthisis and medullary cystic disease complex: Because patients with either juvenile nephronophthisis or medullary cystic disease complex experience excessive thirst and water loss, they will need to replace salt in their diets. Since medical researchers have not found a cause for either of these conditions, the likely outcome is kidney failure, which will require supportive measures.
Tuberous sclerosis (TS): Unfortunately there is no cure for TS but there is treatment for a number of its symptoms and patients should be monitored regularly so they can be treated appropriately. Anti-epileptic drugs may be used to control seizures, and medications may be prescribed for behavior problems.
Von Hippel-Lindau disease: There is no cure for this disease and the treatment is symptomatic support. If a urologist suspects a cyst is actually a tumor, they will remove the growth and a portion of the kidney. When lesions are larger than four centimeters, a more aggressive approach — such as a removal of the organ (nephrectomy) — might be required.
Multicystic dysplastic kidney (MCDK): The treatment for a multicystic kidney varies. Some pediatric urologists favor early renal tumor removal that can often be done as an outpatient procedure. Others favor observation since long-term problems associated with unilateral MCDK are rare and the kidneys will often become smaller.
Renal cyst: Observation is the treatment for a simple renal cyst. Only when symptoms develop, do urologists drain or remove it.
Medullary sponge kidney: There is no cure for medullary sponge kidney. Instead, treatment centers on management of stone formation and urinary infections. Water pills may be effective in decreasing the calcium output and limiting stone formation. Patients who have recurrent urinary infections may benefit from long-term, low-dose antibiotics.
Acquired renal cystic disease: Individuals who exhibit symptoms may benefit from removal of the kidney, particularly if they are already undergoing dialysis.
Frequently asked questions:
How do I know if my cystic kidney disease is getting worse?
Flank pain, blood in the urine or urinary tract infections could be an indicator that cystic kidney disease has progressed. But the disease may also progress silently with no obvious signs or symptoms. The status of your kidney will influence any follow-up studies your urologist orders. Since there are no cures for these problems, long-term care is required. In any case, it is essential to follow your doctor's recommendation regarding management over time.
What makes a disorder "autosomal dominant" or "autosomal recessive"?
Both of these terms suggest a genetic disorder, caused either wholly or in part by a fault in genetic material (DNA) within an individual's cells. Autosomal dominant refers to disorders in which only a single defective gene from one parent is needed to cause the abnormality. Each child then has a 50 percent chance of inheriting the defective gene and of being affected. Autosomal recessive means both parents must pass along the faulty gene, even though they often do not manifest the problem but are merely carriers. Each child has a one in four chances of being affected and one in two chances of being just the carrier.
I've been diagnosed with kidney cystic disease. Should my children be evaluated?
Many kidney cystic diseases are inherited. The specific disorder will determine whether your urologist recommends that your children be evaluated. Even though kidney disease cannot be cured, early evaluation in children to decrease possible symptomatic problems can be helpful.
My child has been diagnosed with renal cystic disease. Should I be evaluated?
Some of the cystic kidney diseases that children have are hereditary, so one parent may also be affected. For the majority of patients, however, there is already a known family history of a similar renal cystic condition. While identifying an adult with such problems can help in making long-term management decisions, identifying renal cystic disease in someone who is otherwise normal may cause future health insurance problems. Since treatment is based on symptoms, it is helpful for any parent to discuss the pros and cons of early diagnosis with a urologist.
Reviewed: January 2011