Polycystic Kidney Disease (PKD) – Causes, Symptoms, and Treatment.

Definition

Polycystic kidney disease is the inherited kidney disease that affects the kidney and other organs. The fluid-filled sacs are developed in the kidney and that disrupts the kidney filtering function and their ability to filter waste products from the blood. The cyst formation causes the kidney to become enlarge and may lead to kidney failure. The cyst may also develop in other organs such as the liver. PKD severity and complications vary based on the cyst size.

Epidemiology

• Autosomal-dominant PKD (ADPKD) occurs worldwide and in all races. Prevalence in the US is estimated to be between 1 in 400 (including observed and estimated autopsy cases) and 1 in 1000 (clinically diagnosed cases only). Approximately 600,000 Americans are affected by the disease, with over 2000 patients starting renal replacement therapy reported due to cystic kidney disease every year.
• In Copenhagen, prevalence is estimated to be 1 in 1000; however, lower figures have been reported in France (1 per 1111), Wales (1 per 2459), and Japan (1 per 4033). In Seychelles, the prevalence in the white population was found to be 1 in 544, but the disease was rare in black people.
• ESRD due to ADPKD is less common among black people than among white people because of the higher incidence of ESRD from other causes in black people.
• Annual US incidence rates for ESRD caused by ADPKD (1998-2001) was 8.7 million in men and 6.9 million for women; in Europe (1998-1999) the rates for men were 7.8 million and 6 million for women; and in Japan, 5.6 million for men (1999-2000) and 4 million women. Autosomal recessive PKD is far less common with an incidence of 1 in 10,000 to 1 in 40,000

Pathophysiology of polycystic kidney disease

• The primary abnormalities lead to cyst formation in both the types recessive and autosomal dominant forms of PKD.
• It is related to the defects in cilia-mediated signaling activity and mainly due to the defect in the primary cilium an immotile, hair-like cellular organelle present on the surface of most cells in the body, anchored in the cell body by the basal body.
• In the kidney, primary cilia have been found to be present in most cells of the nephron, projecting from the apical surface of the renal epithelium into the tubule lumen.
• In response to fluid flow over the renal epithelium, the primary cilium is bent, resulting in a flow-induced increase in intracellular calcium.
• Polycystin-1, Polycystin-2, and fibrocystin, the proteins associated with ADPKD and ARPKD, within the primary cilia and basal body of renal tubular epithelia, suggesting that defects in these proteins and subsequent cilia formation may lead to PKD

Types

There are three main types of PKD

Autosomal Dominant PKD (ADPKD): This type of PKD occurs is passed from parents to the child by dominant inheritance. The one copy of the abnormal gene is needed to cause the disease. Symptoms occur usually between 30 to 40 ages. Sometimes it may begin in the early childhood days; it is the most common forms of PKD which about 90% of the PKD cases are ADPKD

Infantile or Autosomal Recessive PKD (ARPKD): This type occurs by recessive inheritance passed from parent to child. It may arise in the early beginning days of childhood or it starts when the baby inside the mother womb. It will be very serious and tend to progress rapidly. It is more often fatal in the first few months of life. This type of ARPKD is rare since it occurs 1 in 25000 people.

Acquired Cystic Kidney Disease (ACKD): It may happen in the kidney with long-term damage and serves to scar. Thus it leads to kidney failures and dialysis. Symptoms occur such as blood in urine, it is because the cyst bleeds into the urinary system and it discolors the urine. About 90 percent of people on dialysis for 5 years develop ACKD.

Risk factors of polycystic kidney disease

• Diverticular disease of colon
• Chronic Peritoneal Dialysis
• Family history of disorder
• Kidney Stones
• Liver Cyst
• Pancreatic Cyst
• Cyst of testes
• Parental Carrier of Gene

Causes

The abnormal gene causes the polycystic kidney disease. Mostly it runs in the families and sometimes it occurs by single gene mutation so that neither parent has a copy of the mutated gene.

Symptoms

Usually, the most common symptoms associated with kidney diseases are the pain in the back and sides of the ribs, and headache. The symptoms can be mild or severe and occur intermittently or persistently as follows:

• Swollen and tender abdomens
• A lump on either side of the tummy
• Enlarged kidney
• Kidney stones
• High blood pressure
• Blood in the urine or haematuria
• Urinary tract infections
• Liver and pancreatic cysts
• Feeling fullness or indigestion due to the impact of pressure by the enlarged kidneys

Complications of polycystic kidney disease

• A hernia
• Abnormal heart valves such as an aneurysm
• Kidney infection
• Diverticulosis (small pouches in the bowel)
• Loss of kidney function
• Colon problems
• Chronic pain
• Inability to lie still in one position
• Renal failure
• Sclerosis of the renal arterioles and capillaries
• Destruction of the nephrons by expanding cysts

Diagnosis and Test

Imaging studies

The major and foremost diagnosing parameter is the size of the kidney. There are certain imaging techniques to visualize and measure the kidney size as follows.

• MRI scan.
• CT -scan.
• Ultrasound

Genetic testing

A genetic test is done to screen the mutations of PKD1 or PKD2, although it is limited by their cost and the test’s inability to make a diagnosis. The genetic test is performed only for the following reasons.

• A young adult with the family history of PKD.
• A person whose imaging results are not certain information on PKD.
• Pregnant women with family history of PKD.

Pre-implantation screening: For the families who decide to have IVF (in vitro fertilization) procedures, can be screened for PKD mutation to ensure no PKD with the developing embryo.

Polycystic kidney disease treatment

PKD treatment focuses mainly on reducing the progression of kidney failure and to treat the associated effects such as kidney infections, kidney stones, and abdominal pain.

High blood pressure: high BP can be slowed down to control the progression of kidney failure. Medications such as angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs) can be used to control high blood pressure

Dietary restriction: Consuming a low-sodium, low-fat diet that’s moderate in protein and calorie content with not smoking, increasing exercise and reducing stress may help control high blood pressure.

Kidney failure: Kidney transplantation can help for the survival of the PKD patient.

Blood in the urine: To reduce such problem drink plain water to dilute the urine as soon as you noticed blood in the urine.

Bladder or kidney infections: Use appropriate antibiotics with prompt concentrations and doses.

Aneurysms: Controlling high BP automatically will reduce the damaged blood vessels. In the severe cases please inform get a help from a doctor.

Pain: Pain relief tablets can be given to get rid of from the vigorous pain in the back and sides of the kidney.

Tolvaptan: Tolvaptan is taken orally (as a tablet). It can slow the rate at which your kidneys become enlarged by cysts and can help to slow the speed at which your kidney function declines. Tolvaptan does not alter the growth of liver cysts.

Prevention of polycystic kidney disease

• Following strict diet without lipid, avoiding sports, and BP control are all initial options.
• Smoking cessation, regular exercise.
• Low sodium, restricted protein, and a low-cholesterol diet should be followed yearly.
• Patients suspected of PKD should avoid caffeine. Minimize daily caffeinated beverage intake and avoid caffeine-containing foods or related drugs, such as theophylline as they increase levels of cAMP in vitro, which exhibits exacerbate cyst enlargement.