Renal: HUS, Polycystic Kidney & Wilms Tumour

Question 1

What is haemolytic uraemic syndrome (HUS)?

Answer 1

Involves thrombosis in small blood vessels throughout the body, usually triggered by Shiga toxins from either E. coli O157 or Shigella.

Question 2

What is HUS most common caused by?

Answer 2

Infection with certain strains of E. coli –> classically Shiga toxin-producing E.coli coli 0157

i.e. following gastroenteritis

Question 3

What age group dpoes HUS typically affect?

Answer 3

<5 y/o

Question 4

Give 3 causes of HUS

Answer 4

1) E. coli 0157 producing Shigella toxin

2) pneumococcal infection

3) HIV

Question 5

What triad of features is seen in HUS?

Answer 5

1) AKI

2) microangiopathic haemolytic anaemia

3) thrombocytopenia

Question 6

What increases the risk of HUS in gastroenteritis?

Answer 6

Use of antibiotics and anti-motility medication (e.g., loperamide) increases the risk.

Question 7

What is microangiopathic haemolytic anaemia (MAHA)?

Answer 7

Involves haemolysis (destruction of RBCs) due to pathology in small vessels (microangiopathy).

Tiny blood clots (thrombi) partially obstruct the small blood vessels and churn the red blood cells as they pass through, causing them to rupture.

Question 8

What will a FBC show in HUS?

Answer 8

Anaemia & thrombocytopenia

Question 9

What will a blood film show in HUS?

Answer 9

Fragmented blood film

Question 10

Investigations in HUS?

Answer 10

1) FBC
2) Blood film
3) U&Es: will show AKI
4) Stool culture

Question 11

What causes thrombocytopenia in HUS?

Answer 11

The formation of blood clots consumes platelets, leading to thrombocytopenia.

Question 12

What causes AKI in HUS?

Answer 12

The blood flow through the kidney is affected by thrombi and damaged RBCs.

Question 13

What is typically the first symptom of HUS?

Answer 13

Diarrhoea that turns bloody within 3 days.

Question 14

Features of HUS?

Answer 14

• Blood diarrhoea
• Fever
• Abdominal pain
• Lethargy
• Pallor
• Oliguria
• Haematuria
• Hypertension
• Bruising
• Jaundice (due to haemolysis)
• Confusion

Question 15

Purpose of stool culture in HUS?

Answer 15

To establish the causative organism.

Question 16

Management of HUS?

Answer 16

HUS is a medical emergency and requires hospital admission and supportive management with treatment of:

1) Hypovolaemia (e.g., IV fluids)

2) Hypertension

3) Severe anaemia (e.g., blood transfusions)

4) Severe renal failure (e.g., haemodialysis)

Question 17

Prognosis of HUS?

Answer 17

It is self-limiting, and most patients fully recover with good supportive care.

Question 18

What are the 2 types of polycystic kidney disease (PKD)?

Answer 18

1) Autosomal recessive polycystic kidney disease (ARPKD)

2) Autosomal dominant (ADPKD)

Question 19

Which type of PKD usually affects adults and which affects children?

Answer 19

Autosomal dominant - adults (presents later in life).

Autosomal recessive - presents in neonates and is usually picked up on antenatal ultrasound scans.

Question 20

What mutation is the cause of ARPKD?

Answer 20

Polycystic kidney and hepatic disease 1 (PKHD1) gene on chromosome 6

Question 21

What does the PKHD1 gene code for?

Answer 21

Fibrocystin/polyductin protein complex (FPC)

Question 22

What is fibrocystin/polyductin protein complex (FPC) responsible for?

Answer 22

Creation of tubules and the maintenance of healthy epithelial tissue in the kidneys, liver and pancreas.

Question 23

How does ARPKD present?

Answer 23

1) Cystic enlargement of the renal collecting ducts

2) Oligohydramnios

3) Pulmonary hypoplasia

4) Potter syndrome

5) Congenital liver fibrosis

Question 24

How is ARPKD usually picked up?

Answer 24

By oligohydramnios and polycystic kidneys seen on antenatal scans.

Question 25

What is oligohydramnios?

Answer 25

A lack of amniotic fluid caused by reduced urine production by the fetus.

Question 26

What is Potter syndrome? What is it caused by?

Answer 26

A group of findings associated with a lack of amniotic fluid and kidney failure in an unborn infant. Cause --> oligohydramnios

Question 27

What are the features of Potter syndrome?

Answer 27

Characterised by dysmorphic features such as underdeveloped ear cartilage, low set ears, a flat nasal bridge and abnormalities of the skeleton.

Question 28

What causes pulmonary hypoplasia (underdeveloped fetal lungs) in ARPKD?

Answer 28

The oligohydramnios leads to pulmonary hypoplasia, resulting in respiratory failure shortly after birth.

Question 29

Prognosis of ARPKD?

Answer 29

Patients may require renal dialysis within the first few days of life. Most patients develop end stage renal failure before reaching adulthood. Around 1/3 will die in the neonatal period. Around 1/3 will survive to adulthood.

Question 30

Patients with polycystic kidney disease have a number of ongoing problems throughout life. What are some of these problems?

Answer 30

1) Liver cirrhosis due to fibrosis 2) Portal HTN leading to oesophageal varices 3) Progressive renal failure 4) HTN due to renal failure 5) Chronic lung disease

Question 31

What is multicystic dysplastic kidney (MCDK)?

Answer 31

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.

Question 32

How is MCDK normally diagnosed?

Answer 32

On antenatal US scans

Question 33

Prognosis of MCDK?

Answer 33

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 34

What are some complications of having a single kidney?

Answer 34

Can put the person at risk of: - urinary tract infections - hypertension - chronic kidney disease later in life.

Question 35

Management of MCDK?

Answer 35

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.

Question 36

What is Wilms' tumour?

Answer 36

Wilms' nephroblastoma is one of the most common childhood malignancies. Tumour affecting the kidneys mainly in children <5.

Question 37

What age does Wilm's tumour typically affect?

Answer 37

<5 y/o

Question 38

Clinical features of Wilms' tumour?

Answer 38

1) abdominal mass (most common presenting feature) 2) painless haematuria 3) flank pain 4) anorexia & weight loss 5) fever 6) lethargy 7) weight loss

Question 39

Are Wilms' tumours unilateral or bilateral?

Answer 39

Unilateral (95%)

Question 40

Metastases are found in 20% of patients with Wilms' tumour. Where is the most common site of metastases?

Answer 40

Lung

Question 41

What is the criteria for a very urgent referral (for an appointment within 48 hours) in regard to Wilms' tumour?

Answer 41

In children with any of the following: 1) a palpable abdominal mass 2) an unexplained enlarged abdominal organ 3) unexplained visible haematuria

Question 42

What is the initial investigation in Wilms' tumour?

Answer 42

US of the abdomen to visualise the kidneys.

Question 43

What 3 investigations are indicated in Wilms' tumour?

Answer 43

1) US abdo --> initially, to visualise the kidneys 2) CT or MRI --> to stage tumour 3) Biopsy --> identify the histology is required to make a definitive diagnosis.

Question 44

Management of Wilms' tumour?

Answer 44

1) Nephrectomy: surgical excision of the tumour along with the affected kidney 2) Adjuvant treatment: chemo or radiotherapy

Question 45

Prognosis of Wilms' tumour?

Answer 45

Early stage tumours with favourable histology hold a good chance of cure (up to 90%). Metastatic disease has a poorer prognosis.