What is Polycystic kidney disease (PKD)

Polycystic kidney disease (PKD) is an inherited kidney disease (with autosomal dominant inheritance — if one parent carries the gene, statistically 50% of the children will develop kidney disease) with formation of multiple clusters of cysts on the kidneys. The exact mechanism that triggers kidney cyst formation is known.

Statistics on Polycystic kidney disease (PKD)

There are two types of adult polycystic kidney disease:

1. Autosomal Dominant Polycystic Kidney Disease (ADPKD): This condition has a prevalence of 1:300 – 1:1,000, accounting for approximately 10% of end stage renal failure in the United States.

2. Autosomal Recessive Polycystic Kidney Disease (ARPKD): This condition is rare with a prevalence of 1:10,000 – 1:40,000. The progression to end stage renal failure in the condition is less likely as there is more variablity in the severity and course of disease.

Risk Factors for Polycystic kidney disease (PKD)

The only predisposing factor for the development of polycystic kidney disease is a family history of kidney disease. Although some cases occur from spontaneous mutations, such events occur at random and there is little known about risk factors for these mutations.

Progression of Polycystic kidney disease (PKD)

ADPKD:

Kidney disease is usually present at birth but manifests clinically by the third or fourth decade of life. As the cysts enlarge, kidney function will inevitably decline.

High blood pressure is found in 20-30% of children and is present in the overwhelming majority of adults with kidney disease. If the blood pressure remains high, it may result in the accelerated development of end stage renal failure. UIrinary tract infections are also common to this condition.

Kidney disease complications such as calcium deposition in the kidneys and urinary stone (kidney stones) formation may also occur.

ARPKD:

Kidney disease is usually diagnosed in early life with the development of bilateral abdominal masses. The development of end stage renal failure is more variable in this condition, with many sustaining good renal function for many years. As this condition features cystic disease of other organs including the liver, patients with this condition may also suffer from liver disease with the expansion of liver cysts.

How is Polycystic kidney disease (PKD) Diagnosed?

If a kidney disease patient is suspected to carry polycystic kidney disease, the overall function of their kidneys should be assessed. Blood samples will be taken to identify any changes in kidney function.

Prognosis of Polycystic kidney disease (PKD)

ADPKD:

Patients with Adult Polycystic Kidney Disease will expereience a steady decline in renal function throughout their lives. This deterioration is accelerated by recurrent urinary tract infection and high blood pressure, occurring more commonly in males and patients diagnosed at an early age.

ARPKD:

Again, a steady decline in renal function over time can be expected in this condition, accelerated by urinary tract infection and high blood pressure. The rate of decline in renal funcion, however, is more variable in recessive form of disease.

How is Polycystic kidney disease (PKD) Treated?

The two aims of treatment in polycystic kidney disease is to slow the progression of renal failure and reduce symptoms caused by the condition. To slow the progression of renal failure, hypertension and urinary tract infection are treated vigorously. This will also serve to reduce the severity and duration of symptoms associated with urinary tract infection. Chronic abdominal pain may be treated with simple pain relief medications but if the cause is known to be a pyocyst, then pain may be relieved effectively with fine needle aspiration of the cyst contents.

Polycystic kidney disease (PKD) References

[1] Braunwald, Fauci, Kasper, Hauser, Longo, Jameson. Harrison’s Principles of Internal Medicine. 15th Edition. McGraw-Hill. 2001.
[2] Cotran, Kumar, Collins 6th edition. Robbins Pathologic Basis of Disease. WB Saunders Company. 1999.
[3] Kumar P, Clark M. CLINICAL MEDICINE. WB Saunders 2002 Pg 545-549.
[4] Longmore M, Wilkinson I, Torok E. OXFORD HANDBOOK OF CLINICAL MEDICINE. Oxford University Press. 2001.