Polycystic Kidney Disease

Patient presentation:
Thirty year old Caucasian male presents to his general practitioner for increasing back pain, which he states has become increasingly worse over the past several months. He describes the pain as “sharp and crampy,” and indicates to his mid back as the location of the pain.  Pt denies fever, chills, frequent urination, pain on urination or recent trauma.  Past medical history is significant only for moderate hypertension, which is well controlled on current medication regimen.  Family history is unobtainable.  Routine labs were drawn, including CBC, CMP and urinalysis.  Upon physical examination pt is found to have CVA tenderness. Deep palpation of the abdomen elicits pain bilaterally and evidences enlarged kidneys.  Based on physical findings pt is sent for a CT scan.

Differential list:
Pyelonephritis, Nephrolithiasis, Polycystic Kidney Disease/Cystic Kidneys (PKD), and Renal Carcinoma

Diagnosis:
Significant lab results: Urinalysis revealed hematuria and proteinuria; BUN= 40 (normal 7-18) Creatinine 2.7 (normal 0.6-1.2); CT scan revealed diffuse renal cysts bilaterally; genetic testing indicates Autosomal Dominant PKD, due to mutations on either gene PKD-1 or PKD-2.

Polycystic Kidney Disease is a genetic disorder characterized by multiple cyst development on the kidneys.  It accounts for 4% of kidney disease worldwide.  There are two types: Autosomal Dominant PKD and Autosomal Recessive PKD.  The recessive version is significantly less common.  ADPKD is a late-onset disorder involving multiple cyst development and enlarged kidneys bilaterally.  It arises from mutations on PKD-1, located on chromosome 16, or PKD-2, located on chromosome 4.  These genes regulate the growth of tubular epithelium and defects in the gene cause cysts to form, resulting in damage to the kidney, loss of functional nephrons, and eventual ESRD.   The cysts in ADPKD occur slowly and symptoms generally do not begin until early adulthood.  The most common symptoms include back or flank pain, gross hematuria and renal stones.  Individuals can have infections occur within the cysts.  On initial presentation affected individuals will often have hypertension and decreasing renal function.  Diagnosis is usually aided with a family history and CT, or renal ultrasound, which reveal the cystic lesions.  Diagnosed patients must be followed by a nephrologist for common complications including pyelonephritis, nephrolithiasis and decreased renal function.

Treatment:
Treatment is largely supportive.  There is no cure for PKD and progression of the disease to ESRD may require kidney transplant.  Blood pressure control is crucial to slowing the decline in kidney function.  A multi-drug approach, including ACE inhibitors, is usually adopted to control blood pressure.  This pt was monitored closely by nephrologist and was informed that he would likely be placed on the transplant list in the future as he would probably eventually meet the criteria for full end-stage renal disease.

Outcome:
As expected, the patient's disease progressed, but prior to being placed on dialysis he received a living donor transplant from his wife.  The transplant was successful and the patient is followed closely by his transplant team and nephrologist.  Shortly after transplantation the patient's kidney function was restored to normal levels.  The patient will remain on anti-rejection medication for life.
Case created by Nadine Zakhour Diliberto, 2010.