Polycystic Kidney Disease

Question 1

Types of PKD?

Answer 1

There are two types of polycystic kidney disease (PKD). This section focuses on autosomal recessive polycystic kidney disease (ARPKD). Autosomal dominant, known as ADPKD, presents later in life, usually in adults.

Question 2

How does ARPKD present?

Caused by?

Answer 2

Autosomal recessive polycystic kidney disease (ARPKD) presents in neonates and is usually picked up on antenatal ultrasound scans. It is the result of a mutation in the polycystic kidney and hepatic disease 1 (PKHD1) gene on chromosome 6. This gene codes for the fibrocystin/polyductin protein complex (FPC), which is responsible for the creation of tubules and the maintenance of healthy epithelial tissue in the kidneys, liver and pancreas.

Question 3

Features of ARPKD?

Answer 3

The underlying pathology causes:

Cystic enlargement of the renal collecting ducts
Oligohydramnios, pulmonary hypoplasia and Potter syndrome
Congenital liver fibrosis

ARPKD usually presents in the antenatal period with oligohydramnios and polycystic kidneys seen on antenatal scans. Oligohydramnios is a lack of amniotic fluid caused by reduced urine production by the fetus. A lack of amniotic fluid leads to Potter syndrome, which is characterised by dysmorphic features such as underdeveloped ear cartilage, low set ears, a flat nasal bridge and abnormalities of the skeleton. The oligohydramnios leads to underdeveloped fetal lungs (pulmonary hypoplasia), resulting in respiratory failure shortly after birth. Additionally, large cystic kidneys can take up so much space in the abdomen it becomes hard for the neonate to breath adequately. Patients may require renal dialysis within the first few days of life. Most patients develop end stage renal failure before reaching adulthood.

Question 4

Complications of ARPKD?

Answer 4

Patients with polycystic kidney disease have a number of ongoing problems throughout life:

Liver failure due to liver fibrosis
Portal hypertension leading to oesophageal varices
Progressive renal failure
Hypertension due to renal failure
Chronic lung disease

Question 5

Prognosis of ARPKD?

Answer 5

The prognosis is poor. Survival depends of very extensive interventions from a number of different specialties both in the neonatal period and throughout life. Around 1/3 will die in the neonatal period. Around 1/3 will survive to adulthood.

Question 6

What is multicystic dysplastic kidney?

Answer 6

Multicystic dysplastic kidney (MCDK) is a separate condition to PKD, where one of the baby’s kidneys is made up of many cysts while the other kidney is normal. In rare cases it can be bilateral, which inevitably leads to death in infancy. MCDK is normally diagnosed on antenatal ultrasound scans.

Question 7

Consequences of MCDK?

Answer 7

Usually the single healthy kidney is sufficient to lead a normal life. Often the cystic kidney will atrophy and disappear before 5 years of age. Having a single kidney can put the person at risk of urinary tract infections, hypertension and chronic kidney disease later in life.

Question 8

Management of MCDK?

Answer 8

No treatment is required for MCDK. Followup renal ultrasound scans can be used to monitor the abnormal kidney. Prophylactic antibiotics are occasionally used to prevent urinary infections that may affect the working kidney.