Polycystic kidney disease

Question 1

What are the 2 types of PKD?

Answer 1

1. Autosomal recessive polycystic kidney disease - childhood
2. Autosomal dominant polycystic kidney disease - presents later in life, usually in adults

Question 2

What is autosomal recessive polycystic kidney disease (ARPKD)?

Answer 2

Presents in neonates and is usually picked up on antenatal USS

Question 3

What is the cause of ARPKD?

Answer 3

• 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

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 4

What are the features of ARPKD?

Answer 4

The underlying pathology causes:
1. Cystic enlargement of the renal collecting ducts
2. Oligohydraminos, pulmonary hypoplasia, and Potter syndrome
3. Congenital liver fibrosis

Question 5

how is it diagnosed?

Answer 5

in the neonatal period with oligohydraminos and polycystic kidneys seen on antenatal scan

Question 6

How does ARPKD present?

Answer 6

• oligohydraminos 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 an underdeveloped ear cartilage, low set ears, a flat nasal bridge and abnormalities of the skeleton
• the oligohydraminos leads to underdeveloped fetal lungs (pulmonary hypoplasia), ⇒ respiratory failure shortly after birth
• also, large cystic kidneys can take up so much space in the abdomen that is becomes hard for the neonate to breathe adequately
• patients may need renal dialysis within the first few days of life
• most patients develop end stage renal failure before reaching adulthood

Oligohydraminos is a lack of amniotic fluid caused by reduced urine production by the fetus, leading to Potter syndrome, characterized by dysmorphic features such as underdeveloped ear cartilage, low set ears, a flat nasal bridge, and abnormalities of the skeleton.

Question 7

What is Potter syndrome?

Answer 7

Caused by a lack of amniotic fluid and characterized by dysmorphic features such as:
1. Underdeveloped ear cartilage
2. Low set ears
3. Flat nasal bridge
4. Abnormalities of the skeleton

Question 8

What are some ongoing problems associated with PKD?

Answer 8

1. Liver failure due to liver fibrosis
2. Portal hypertension leading to oesophageal varices
3. Progressive renal failure
4. Hypertension due to renal failure
5. Chronic lung disease

Question 9

What is multi-cystic dysplastic kidney (MCDK)?

Answer 9

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.

Question 10

How is MCDK diagnosed?

Answer 10

Usually on antenatal USS

Question 11

What is the prognosis for MCDK?

Answer 11

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.

Question 12

What are the risks of a single kidney?

Answer 12

1. UTI
2. Hypertension
3. CKD later in life

Question 13

What is the management for MCDK?

Answer 13

No treatment is needed. Follow up renal USS can be used to monitor the abnormal kidney. Prophylactic antibiotics are occasionally used to prevent urinary infections that may affect the working kidney.