Renal: HUS, Polycystic Kidney & Wilms Tumour Flashcards
What is haemolytic uraemic syndrome (HUS)?
Involves thrombosis in small blood vessels throughout the body, usually triggered by Shiga toxins from either E. coli O157 or Shigella.
What is HUS most common caused by?
Infection with certain strains of E. coli –> classically Shiga toxin-producing E.coli coli 0157
i.e. following gastroenteritis
What age group dpoes HUS typically affect?
<5 y/o
Give 3 causes of HUS
1) E. coli 0157 producing Shigella toxin
2) pneumococcal infection
3) HIV
What triad of features is seen in HUS?
1) AKI
2) microangiopathic haemolytic anaemia
3) thrombocytopenia
What increases the risk of HUS in gastroenteritis?
Use of antibiotics and anti-motility medication (e.g., loperamide) increases the risk.
What is microangiopathic haemolytic anaemia (MAHA)?
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.
What will a FBC show in HUS?
Anaemia & thrombocytopenia
What will a blood film show in HUS?
Fragmented blood film
Investigations in HUS?
1) FBC
2) Blood film
3) U&Es: will show AKI
4) Stool culture
What causes thrombocytopenia in HUS?
The formation of blood clots consumes platelets, leading to thrombocytopenia.
What causes AKI in HUS?
The blood flow through the kidney is affected by thrombi and damaged RBCs.
What is typically the first symptom of HUS?
Diarrhoea that turns bloody within 3 days.
Features of HUS?
- Blood diarrhoea
- Fever
- Abdominal pain
- Lethargy
- Pallor
- Oliguria
- Haematuria
- Hypertension
- Bruising
- Jaundice (due to haemolysis)
- Confusion
Purpose of stool culture in HUS?
To establish the causative organism.
Management of HUS?
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)
Prognosis of HUS?
It is self-limiting, and most patients fully recover with good supportive care.
What are the 2 types of polycystic kidney disease (PKD)?
1) Autosomal recessive polycystic kidney disease (ARPKD)
2) Autosomal dominant (ADPKD)
Which type of PKD usually affects adults and which affects children?
Autosomal dominant - adults (presents later in life).
Autosomal recessive - presents in neonates and is usually picked up on antenatal ultrasound scans.
What mutation is the cause of ARPKD?
Polycystic kidney and hepatic disease 1 (PKHD1) gene on chromosome 6
What does the PKHD1 gene code for?
Fibrocystin/polyductin protein complex (FPC)
What is fibrocystin/polyductin protein complex (FPC) responsible for?
Creation of tubules and the maintenance of healthy epithelial tissue in the kidneys, liver and pancreas.
How does ARPKD present?
1) Cystic enlargement of the renal collecting ducts
2) Oligohydramnios
3) Pulmonary hypoplasia
4) Potter syndrome
5) Congenital liver fibrosis
How is ARPKD usually picked up?
By oligohydramnios and polycystic kidneys seen on antenatal scans.
What is oligohydramnios?
A lack of amniotic fluid caused by reduced urine production by the fetus.
What is Potter syndrome?
What is it caused by?
A group of findings associated with a lack of amniotic fluid and kidney failure in an unborn infant.
Cause –> oligohydramnios
What are the features of Potter syndrome?
Characterised by dysmorphic features such as underdeveloped ear cartilage, low set ears, a flat nasal bridge and abnormalities of the skeleton.
What causes pulmonary hypoplasia (underdeveloped fetal lungs) in ARPKD?
The oligohydramnios leads to pulmonary hypoplasia, resulting in respiratory failure shortly after birth.
Prognosis of ARPKD?
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.
Patients with polycystic kidney disease have a number of ongoing problems throughout life.
What are some of these problems?
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
What is multicystic dysplastic kidney (MCDK)?
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.
How is MCDK normally diagnosed?
On antenatal US scans
Prognosis of MCDK?
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.
What are some complications of having a single kidney?
Can put the person at risk of:
- urinary tract infections
- hypertension
- chronic kidney disease later in life.
Management of MCDK?
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.
What is Wilms’ tumour?
Wilms’ nephroblastoma is one of the most common childhood malignancies.
Tumour affecting the kidneys mainly in children <5.
What age does Wilm’s tumour typically affect?
<5 y/o
Clinical features of Wilms’ tumour?
1) abdominal mass (most common presenting feature)
2) painless haematuria
3) flank pain
4) anorexia & weight loss
5) fever
6) lethargy
7) weight loss
Are Wilms’ tumours unilateral or bilateral?
Unilateral (95%)
Metastases are found in 20% of patients with Wilms’ tumour. Where is the most common site of metastases?
Lung
What is the criteria for a very urgent referral (for an appointment within 48 hours) in regard to Wilms’ tumour?
In children with any of the following:
1) a palpable abdominal mass
2) an unexplained enlarged abdominal organ
3) unexplained visible haematuria
What is the initial investigation in Wilms’ tumour?
US of the abdomen to visualise the kidneys.
What 3 investigations are indicated in Wilms’ tumour?
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.
Management of Wilms’ tumour?
1) Nephrectomy: surgical excision of the tumour along with the affected kidney
2) Adjuvant treatment: chemo or radiotherapy
Prognosis of Wilms’ tumour?
Early stage tumours with favourable histology hold a good chance of cure (up to 90%).
Metastatic disease has a poorer prognosis.
