Kidney cysts are common and can be part of a congenital or inherited disease or simply present as a single or multiple cysts unrelated to any disease with no long-term problems. Decisions on the treatment of cystic disease of the kidney should be made with the help of a qualified and experienced doctor.
There are several genetic and inheritable kidney diseases and polycystic kidney disease (PKD) is the most common of them all. It affects several thousand Nigerians and others around the world as well. Approximately 2 to 3 of every 20 cases of kidney failure requiring dialysis or transplant is due to polycystic kidney disease. In Nigeria, while there is no strong evidence, some studies suggest the likelihood of having PKD is higher among men than women.
To read first hand, some of the literature published on polycystic kidney disease in Nigeria, click on the links at the bottom of this post.
There are 2 forms of polycystic kidney disease
1) Autosomal dominant polycystic kidney disease (ADPKD).
This is the most common form of the disease seen in patients in Nigeria. In this form of polycystic kidney disease, there is usually a family history although new mutations in the genes can occur leading to the occurrence in a person with no prior family history. New mutations are the cause of about 10% of cases of PKD and once a mutation occurs in a family, it there is a 50% chance of transmission to each child.
ADPKD results from a mutation in one of two genes. 85% of mutations occur in chromosome 16 (PKD1 gene) and makes a protein called polycystin-1; 15% of mutations occur in chromosome 4 (PKD2 gene) and makes a protein called polycystin-2. Remember that each cell contains pairs of chromosomes (one from either parent) and only one mutated gene of a chromosome pair is required for the disease to occur. The mutated gene can come from either parent. Every child carrying one mutated gene will have ADPKD. Every conception has a 50% chance of the child inheriting the mutated gene and having ADPKD. The disease does not present in childhood but begins to develop in the mid 20-s to 30’s. Half of the people with PKD between the age of 57 and 73 will develop end stage kidney disease. However, some patients may present much earlier or later than the age of 50 years.
2) Autosomal recessive polycystic kidney disease (ARPKD)
Autosomal recessive polycystic kidney disease (ARPKD) is a relatively rare form of PKD, affecting approximately 1 in 20,000 children. ARPKD results from a mutation in chromosome 6 (PKHD gene). This gene pair makes a protein called fibrocystin or polyductin. Both genes of the chromosome pair must carry the mutation for the disease to occur. There is no family history of the disease in affected children because each parent carries only one mutated gene. Each conception carries a 25% chance of the child inheriting both mutated genes and having ARPKD. ARPKD often causes death in the first month of life. For ARPKD children who survive the newborn period (about 70 percent), approximately one-third will need dialysis or transplantation by age 10. Previously thought to be a fatal condition, the prognosis for children with ARPKD has improved dramatically in countries where sufficient medical care and technology exists.
As the name suggests, PKD is a disease where there is an abnormal formation of many fluid filled sacs in the main tissue of the kidney and occasionally in other organs such as the liver. These fluid filled sacs are not cancerous but in regions where these sacs or cysts exists, the normal organ tissue there is destroyed. These fluid filled sacs increase in size and further damage nearby normal tissue causing a worsening of organ function. The enlargement and increase in number of the cysts often leads eventually to kidney failure and only very rarely does the disease lead to liver failure. Enlargement of the cysts often occurs over years but once established, the cysts are not reversible. Research is ongoing to identify treatments to reduce the rate of growth of the cysts but no successes have been made yet.
The signs and symptoms of polycystic kidney disease can range from having no symptoms in the early stages of the disease to having many signs and symptoms such as
- High blood pressure (hypertension)
- Frequent urinary tract infections
- Blood in urine (hematuria)
- Protein in urine (proteinura)
- Urinary tract and cyst infection
- Mitral valve prolapse- abnormal functioning of an important valve in the heart
- Back/flank pain due to enlargement or rupture of kidney or liver cysts
- Kidney stones. There is an increased risk of kidney stones in patients with PKD.
- Enlarged kidneys with effects on breathing and amount of food a person can eat because of the size of the kidney occupying a lot of the belly space.
- Depression and anxiety (due to stress and emotional impact)
- Aneurysms (bulging of the blood vessel walls) in the brain that could burst and cause stroke
- Diverticulosis (pouches in the intestines) that could burst or get infected and cause a lot of belly pain
How do I know if I have PKD?
Unless a patient has any of the symptoms listed above, ultrasound is the only way to determine if PKD is present. People less than 20 years of age without symptoms do not need to be tested. For those above the age of 20 years with a family history of PKD with or without symptoms there are specific criteria bAsed on age and the number of cysts seen on ultrasound. For instance, a person under the age of 30 with a family history of PKD must have 2 cysts in one or both kidneys while a person over the age of 60 years with a family history of PKD needs to have 4 cysts in each kidney. Genetic testing of family members may also be useful in determining presence of PKD.
Treatment of PKD
- Back/flank pain: testing needs to be performed to ensure that there is no kidney stone, cancer, bleeding or infection all of which can cause pain. Sometimes in the absence of stone, bleeding cancer or infection, the large size of the cysts can cause pain. Treatment of infection, removal of fluid from very large cysts to help reduce pressure and pain are options for treatment. Less frequently surgical removal of the affected kidney is required.
- Treatment of urinary tract and cyst infection: These infections are often frequent and can be severe and may involve infection of the kidney cysts or the liver cysts. Treatment with antibiotics after testing for the kind of bacteria causing the infection sometimes for long periods of time or continuously may be necessary.
- Treatment of kidney stones: treatment of kidney stones in patients with PKD are no different from treatment of kidney stones without PKD.
- Treatment of hypertension: Very good control of high blood pressure is very important because high blood pressure speeds up the rate of progression to kidney failure.
- Treatment of kidney failure: Dialysis or kidney transplantation is effective in treating cases of advanced PKD.
- Treatment of brain aneurysms: stroke is a complication of PKD in some patients who develop aneurysms in the brain. Effective blood pressure control and in some cases surgery to clip the aneurysm is needed.