Polycystic kidney disease

  • Polycystic kidney disease is characterized by the presence of numerous cysts in the kidneys, with increased size and decreased functional capacity. 

There are two major forms of polycystic kidney disease: Autosomal dominant polycystic kidney disease (ADPKD) and Autosomal recessive polycystic kidney disease (ARPKD). ADPKD is the most common inherited disorder, occurring in about 1 in 400 to 1000 people. The autosomal dominant in genetics has two characteristics – there’s a 50% chance for an affected person to inherit the condition from an affected parent, and, moreover, the dominantly inherited diseases typically do not skip generations, since the disease is passed with the genetic variation from a parent to a child. However, some patients with ADPKD are not diagnosed during their lifetime due to the absence of symptoms, and as a result a family member may suffer from the disease without knowing it.

  • What is the kind of damage occurred in kidney tissue?

The damage in ADPKD causes abnormal growth of kidney cells, and thus kidney cysts are created. Then the kidney’s size is increased, usually due to the secretion of fluids therein. This often leads to progressive renal insufficiency mainly due to the ongoing bladder enlargement and the replacement of normal kidney tissue from the cysts. Other kidney problems, such as high blood pressure, kidney infection, blood in the urine (hematuria) and kidney stones, may also occur. Moreover, pain and abdominal pain are also common.

  • What are the clinical manifestations and complications of the disease?

Renal insufficiency - ADPKD is the third most common cause of end-stage renal failure apart from hypertension and diabetes but rarely leads to end-stage CKD in early childhood. It often appears in middle - aged people or later on. The probability of end-stage CKD in ADPKD individuals is estimated to be less than 2% in people under 40 years old, increases to 50 - 75% at the ages of 70 - 75 years. Not all patients with ADPKD suffer from kidney failure. The risk of developing renal insufficiency in ADPKD depends on various factors, with the increase in kidney size being the most reliable predictor of renal failure in patients with ADPKD. In addition, males and people with PKD1 disease who have episodes of visible blood or protein in the urine or high blood pressure (especially before the age of 35) seem to have an increased risk of developing renal failure. Larger kidneys due to the high number of cysts are associated with all these complications and seem to be the most important risk factor to kidney failure.

Arterial Hypertension - High blood pressure is a common feature of ADPKD, which occurs in 60-70% of patients with normal renal function up to the age of 30 years. Over 90% of patients will eventually have high blood pressure before they reach the end stage renal failure. Men have higher arterial pressures than women, and high blood pressure is associated with larger kidneys and faster kidney growth rates.

Infections - About 30-50% of people with ADPKD will have at least one infection in one of the cysts during their lifetime. The main symptoms are fever and back pain. Not all antibiotics are appropriate if the infection is in a bladder. The nephrologist should prescribe the appropriate antibiotics and the duration of treatment for a cyst or kidney infection is typically longer than with a routine kidney infection in someone without ADPKD.

Blood in the urine - Hematuria (blood in the urine) occurs in 35 - 50 percent of people with ADPKD and may be the first sign of the disease. It is usually macroscopic (visible) to the patient. Recurrent episodes of hematuria are common. Hematuria is associated with a faster rate of kidney size increase but also with a large kidney size. It can happen because of intense physical activity and can cause localized pain in the kidney. Hematuria in these patients can also be caused by stones in the polycystic kidney, another common complication. Hematuria associated with bleeding cysts generally stops within two to seven days. The usual treatment involves resting on the bed and raising the fluid until bleeding stops. If bleeding does not stop with bedtime and elevated fluid, a special procedure may be required to stop bleeding.

Nephrolithiasis (kidney stones) - It is a relatively common complication of ADPKD for nearly 25% of these patients. They can cause pain or sometimes can prevent urine flow without symptoms. In this case the treatment of the stones is extremely important. If blockage is not prevented, the function in the kidney can be lost.

Pain in kidney areas - Pain is the most common feature of ADPKD. People with ADPKD often have back and abdominal pain that is not associated with infection, bladder bleeding or renal stone. The pain cannot be accurately detected, it is often persistent and is caused by the stretching or the pressure of the bladder wall on other organs when the kidneys and / or the liver are too large. Instead, if pain suddenly begins, the most likely cause is bleeding or bladder or stone infection. Strenuous pain, especially if it is not minimized with common painkillers, should be examined by your nephrologist.

In addition to manifestations from the kidney, there are also extrarenal complications of the disease:

Intracranial aneurysm - The most serious possible complication of PKD is cerebral aneurysm (a swollen blood vessel with a thin-brittle wall). Aneurysms can break, causing bleeding in the brain (subarachnoid hemorrhage), and if bleeding is severe, it can lead to irreversible brain damage or death. Aneurysm rupture occurs more frequently in subjects with larger aneurysms (> 10 mm). About 3-7% of young adults with ADPKD may have brain aneurysm and the possibility of having brain aneurysm is increased to 12 - 15 percent if someone else in the patient's family has an intracranial aneurysm. Early detection (before the onset of symptoms) is recommended for people at high risk by performing a magnetic angiography (MRA).

Liver cysts - Liver cysts often appear in people with ADPKD. More than 85% of patients will have liver cysts up to the age of 30. As the patients grow older, liver cysts become larger and more numerous. In addition, women have larger liver cysts than men, especially women who have multiple pregnancies or take contraceptive pills or hormone replacement therapy for prolonged periods of time. Most people with liver cysts have no symptoms and have normal or almost normal liver function.

Valvular diseases - Cardiac valve abnormalities are detected to up to 25% of patients with ADPKD. Most patients with heart valve disease have no symptoms and do not need treatment. A number of patients with mitral valve prolapse may experience palpitations.

  • Mesogeios Dialysis Centers Group Scientific Team 
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  • Bibliography 
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