Polycystic kidney disease

It is an inherited cystic disease of the kidney. There are two types:

1. Adult PKD (APKD): It is inherited as autosomal dominant, common type, males and females are equally affected. Gene on chromosome 16 (PKD1) and 4 (PKD2).
2. Infantile PKD (IPKD): It is inherited as autosomal recessive, rare, associated with cyst in other organs and hepatic fibrosis and fatal in first year due to hepatic or renal failure. Gene on chromosome 6.

*Long Cases in Clinical Medicine, ABM Abdullah

As follows:

• Simple cyst, usually congenital
• Acquired cyst, after dialysis (in chronic renal failure)
• Polycystic kidney disease
• Medullary sponge kidney: Cause is unknown, but not genetic. Cyst is confined to the papillary collecting ducts. Age 40 to 60 years, prognosis is good. Usually no hypertension or no renal failure.
• Medullary cystic disease: Small cysts in cortical area or corticomedullary junction. Renal failure is common, hypertension may occur. The patients usually have polyuria and increased thirst and are salt loser.

*Long Cases in Clinical Medicine, ABM Abdullah

Note: Remember the following points:

• Polycystic kidney disease is always bilateral (may be unilateral, if other kidney is absent)
• Polycystic kidney disease is a misnomer, cyst occurs in many other organs (liver, spleen)
• More common in sickle cell disease, cystic fibrosis, Huntington’s disease
• May be associated with mitral valve prolapse (25%), causing mitral regurgitation, and aortic
  regurgitation (rarely severe)
• Colonic diverticula may occur
• Abdominal wall hernia
• Polycystic kidney disease is not premalignant
• Hypertension is present in 75% cases
• Usually there is polycythemia due to high erythropoietin level. There may be anemia if there is chronic renal failure (however, hemoglobin level is higher than expected for the degree of renal failure).

*Long Cases in Clinical Medicine, ABM Abdullah

Mode of inheritance are:

• Adult polycystic kidney disease—Autosomal dominant
• Infantile polycystic kidney disease—Autosomal recessive.

Pain is due to:

• Acute hemorrhage in the cyst
• Infection in the cyst
• Renal stone
• Renal cell carcinoma rarely.

*Long Cases in Clinical Medicine, ABM Abdullah

As follows:

• May be asymptomatic (renal mass detected on routine examination)
• Vague discomfort, pain or heaviness in loin or abdomen due to increasing mass of renal tissue.
• Recurrent painful hematuria (due to rupture of cyst in renal pelvis or infection) (with little or no proteinuria)
• Recurrent UTI or cyst infection
• Acute loin pain or renal colic due to hemorrhage into a cyst
• Features of hypertension (usually after 20 years of age) and its complications
• Features of renal failure
• CVA (usually subarachnoid hemorrhage, due to rupture of berry aneurysm. Sometimes, may be cerebral hemorrhage as a complication of hypertension).

*Long Cases in Clinical Medicine, ABM Abdullah; Pre-exam preparation for medicine, HN Sarker

As follows:

• Cystic liver—30%, but hepatic dysfunction is rare. There may be cyst in spleen, ovary and pancreas
• Berry aneurysm in circle of Willis—10% (may rupture causing subarachnoid hemorrhage)
• Polycythemia (due to increased erythropoietin secretion)
• Renal stone—10% cases (usually calcium oxalate, urate)
• Renal neoplasm—rarely.

*Long Cases in Clinical Medicine, ABM Abdullah

As follows:

• Ultrasonography (always mention as the first investigation)
• Urine for R/E and C/S
• Full blood count (polycythemia may be found)
• Renal functions—urea, creatinine, serum electrolytes (some patients may be salt looser)
• High resolution CT-Scan or MRI of KUB
• IVU or retrograde pyelography
• Family screening.

*Long Cases in Clinical Medicine, ABM Abdullah

Figure: MRI images of the kidneys. A Normal kidneys. B Polycystic kidneys; although the kidney enlargement is extreme, this patient had only slightly reduced GFR.

Figure: Davidson’s Principles and Practice of Medicine, 22nd edition

Ultra sonogram of whole abdomen.

USG criteria are:

• Person below 30 years—presence of at least 2 renal cysts (unilateral/bilateral)
• Person between 30 to 59 years—presence of at least 2 renal cysts in each kidney
• Persons 60 years and above—at least 4 cyst in each kidney.

*Long Cases in Clinical Medicine, ABM Abdullah

IVU shows:

• Enlargement of both the kidneys
• Stretching, distortion and elongation of pelvicalyceal system (giving rise to spidery appearance).

*Long Cases in Clinical Medicine, ABM Abdullah

Bilateral hydronephrosis with hypertension.

*Long Cases in Clinical Medicine, ABM Abdullah

Subarachnoid hemorrhage due to rupture of berry aneurysm.

Other causes may be:

• Cerebral hemorrhage as a complication of hypertension
• Hyponatremia (salt losing nephropathy).

*Long Cases in Clinical Medicine, ABM Abdullah

As follows:

• Control of hypertension
• Control of urinary tract infection
• Plenty of fluid
• Salt (there may be salt looser in some cases)
• For renal pain or if large cyst, ultrasonic guided aspiration or laparoscopic cystectomy may be
  done
• Treatment of renal failure. Dialysis and even renal transplantation may be done
• Genetic counseling
• Family screening—USG of the abdomen should be done in all members of the family over 20
  years of age to detect cysts.
• MR angiography to detect berry aneurysm may be considered in some cases, where other members
  having history of subarachnoid hemorrhage.

*Long Cases in Clinical Medicine, ABM Abdullah

Death may be due to:

• Chronic renal failure (in one third cases)
• Intracerebral hemorrhage (SAH)
• Myocardial infarction.

*Long Cases in Clinical Medicine, ABM Abdullah