Guidelines for the management and investigation of

Haemolytic Uraemic Syndrome (HUS)

Children’s Kidney Centre University Hospital of Wales Cardiff CF14 4XW DISCLAIMER: These guidelines were produced in good faith by the author(s) in conjunction with the paediatric nephrology team at the University Hospital of Wales, Cardiff reviewing available evidence/opinion. They were designed for use by paediatric nephrologists at the University Hospital of Wales, Cardiff for children under their care. They are neither policies nor protocols but are intended to serve only as guidelines. They are not intended to replace clinical judgment or dictate care of individual patients. Responsibility and decision-making (including checking drug doses) for a specific patient lie with the physician and staff caring for that particular patient.

Dr Graham Smith

June 2017

Summary These guidelines are aimed at providing the doctors presented with a child with suspected HUS with information to guide the investigation and management of the problem. Introduction HUS is the commonest cause of acute renal failure in children in the UK and in the majority of cases it follows infection with verotoxin producing E. coli, the commonest subtype being 0157:H7. There is usually a preceding history of diarrhoea which is frequently bloody. The diagnosis is based on the findings of:

Microangiopathic haemolytic anaemia

Red cell fragmentation on a blood Film

Acute Kidney Injury (AKI) These features whilst most commonly following a diarrhoeal prodrome may also occur after infections with other organisms, drugs, pregnancy or may be familial. It is important to distinguish these forms of the disease as management varies. Initial assessment and management Standard assessment of airway, breathing and circulation and a full history and examination should be undertaken. Attention should be paid to the possibility of contact with farm animals and the presence of diarrhoea in other family members. It is possible that the patient will pre renal failure secondary to hypovolaemia and intravascular volume status should be assessed:

Thirst, restlessness, confusion

Skin Turgor

Fontanelle

Heart Rate

Capillary refill

JVP

Oliguria

Blood Pressure

Evidence of oedema Hypovolaemia should be treated by volume expansion with 0.9% Saline, 4.5% Human Albumin Solution or Packed Red Blood cells depending on clinical status. Initial Investigations

FBC with film and differential

U&E’s and LFT’s

Amylase

LDH

Haptoglobin (requirement for use of eculizumab; speak to haematology)

CRP

Glucose

Coagulation Screen

Group and Save

X match if indicated

E. coli serology (clotted sample to microbiology). Anti-LPS antibody.

Stool culture

Stool for PCR for STEC virulence genes (Colindale)

Urinalysis Fluid management This will depend on the fluid status of the patient and the degree of renal impairment. Hypovolaemia

Boluses of isotonic fluid. This may be 0.9% NaCl, HAS or packed cells depending on clinical status. Give boluses of 10 ml/kg and repeat as necessary.

Euvolaemia

Treatment is aimed at maintaining the patient in a euvolaemic or slightly fluid overloaded state in order to ensure adequate renal perfusion.

Oral fluids if patient drinking

Otherwise intravenous fluids – type of crystalloid dependent on serum [Na+] and need for blood products. If serum [Na+] normal then use 0.45% NaCl + 5% dextrose.

Fluid input: Input = Output (urine + insensible losses + other losses e.g. diarrhoea)

Hypervolaemia

Usually the result of renal dysfunction and oliguria

May be associated with hyponatraemia (see specific guidelines)

Institute fluid restriction. Stop intravenous crystalloid.

If urine output present then trial of furosemide. If renal impairment then can give doses up to 5 mg/kg by slow infusion. Furosemide unlikely to be effective if anuric.

If oliguria / anuria unresponsive to diuretics then need to consider dialysis. Insensible loss = 300 - 400 ml/m2/day. Electrolyte disturbances See Guidelines for the management of Acute Kidney Injury in Children. Hypertension Usually due to fluid overload in acute setting. Therefore manage fluid overload. If persists consider a calcium channel blocker. Nutrition If supplemental nutrition is deemed necessary a nasogastric tube should be inserted at the time dialysis access is obtained. Feeds should be commenced as continuous infusion initially at a slow rate. If enteral feeds not tolerated then use total parenteral nutrition.

See Guidelines for dietary management of children with renal diseases. Dialysis Dialysis is indicated for the management of:

Fluid overload resistant to diuretic therapy

Hyperkalaemia

Intractable Acidosis

Symptoms of uraemia

Likely progression to one of the above The options are peritoneal dialysis or haemodialysis. We favour the use of haemodialysis because of the greater reliability of treatment. An internal jugular line will need to be placed. This can be a temporary or tunnelled line. Given the uncertainty as to how long dialysis may be required a tunnelled line is preferred. This will need to be sited by the on call paediatric surgeon. See Guidelines for Vascular access for haemodialysis. Eculizumab A trial of eculizumab in diarrhoea associated HUS is in place and the trial protocol should be consulted. This trial is planned to start in the latter half of 2017.

Atypical Haemolytic Uraemic Syndrome (aHUS) HUS may follow infection with other serotypes of E. coli and serology for these should be specifically requested if indicated. Similarly other infectious agents have been identified including Strep pneumoniae, Klebsiella and Shigella therefore other potential infectious agents should be sought. Familial cases of HUS are also recognised and a detailed family must therefore be obtained and the parents directly questioned regarding the possibility of consanguinity. Other potential causes

Idiopathic

Drug Toxicity

Chemotherapy, Mitomycin-C, Tacrolimus, Ciclosporin, oral contraceptives, valacyclovir, OKT3, Quinine, Ticlodipine, Clopidorgel

Conditioning for Bone Marrow Transplantation

Solid organ transplantation

Malignancy

Hereditary e.g. Autosomal Recessive or Dominant; Inborn error of cobalamin deficiency

Pregnancy or post partum

AIDS and early symptomatic HIV

Connective Tissue Disease e.g. SLE, Sjorgens, Systemic Sclerosis, antiphospholipid antibody syndrome, scleroderma

Other glomerulonephritides e.g. APIGN, membranoproliferative GN National guidelines for the management of aHUS are available at: http://www.renal.org/docs/default-source/guidelines-resources/joint-guidelines/aHUS_Clinical_Practice_Guidelines_2009.pdf?sfvrsn=0 Investigations (see appendix 1) It is important to bear these other causes in mind as they may be precipitated by a diarrhoeal illness and treatment strategies vary. If there is a suspicion of other causes, the following investigations may be indicated:

Complement studies: o Functional assays (see appendix 2)

CH50 AP50 (Factor H function)

o Serum levels: C3 C4 Factor H Factor I Factor B

o Expression of MCP (CD46) on PBMCs should be assessed using FACS analysis in an appropriately accredited laboratory

o Mutation screening of the genes encoding factor H, MCP, factor

I, factor B and C3 (see appendix 2) o Mutation analysis in THBD o Mutation analysis in DGKE if child presents under 1 year of age o Autoantibodies against factor H o C3 Nef

ADAMTS13 / Von Willebrand cleaving protease activity (TTP). If low then further investigations such as ADAMTS 13 antibodies may be indicated.

Coombs’ test, peanut lectin activity test and pneumococcal PCR (pneumococcal HUS)

Influenza A culture, antigen detection, PCR nasopharyngeal swab or serology

Urinary or plasma/serum methylmalonic acid and plasma homocysteine + methionine (Cobolamin C defect)

Renal Biopsy

Autoantibodies o Anticardiolipin o Antinuclear factor o Anti double stranded DNA o Anti endonuclear

Antiplatelet antibodies

Pregnancy Test

HIV Test An international consensus has been published by Loirat et al. This includes a diagnostic algorithm:

Diagnostic algorithm for atypical HUS in children a) Blood sampling imperatively before plasma exchange/plasma infusion b) Communication of M. Noris, Bergamo, Italy c) Communication of author V. Fremeaux-Bacchi. ADAMTS13: A Disintegrin And Metalloproteinase with a ThromboSpondin type 1 motif, member 13; aHUS: atypical hemolytic uremic syndrome; Cbl-C: cobalamin C; CFB: complement factor B; CFH: complement factor H; CFHRs: complement factor H-related proteins; CFI: complement factor I; CKD: chronic kidney disease; ESRD: end-stage renal disease; CSF: cerebrospinal fluid; DGKE: diacylglycerol kinase ε; FACS: Fluorescence Activated Cell Sorting; HUS: hemolytic uremic syndrome; MCP: membrane

cofactor protein (CD46); MLPA: multiplex ligation dependent probe amplification; PCR: polymerase chain reaction; STEC: Shiga toxin-producing Escherichia coli; Stx: Shiga toxin

Treatment As can be seen by the lists above the term aHUS covers a number of different pathophysiologies which are unlikely to respond to treatment in the same way. The main treatment strategy has been based around plasma exchange but more recently this has been replaced in some cases by administration of the terminal complement inhibitor, eculizumab. NICE has confirmed eculizumab as an effective treatment for aHUS in the document Eculizumab for treating atypical haemolytic urhaemolytic uraemic syndrome. The role of eculizumab is reviewed by Kaplan et al and summarized below:

How to get a patient started on eculizumab? Information about prescribing eculizumab is published in the document: Specialised Services Policy: CP98. Eculizumab for Atypical Haemolytic Uraemic Syndrome (aHUS). This document contains a checklist which should be completed. In addition an Individual Patient Funding Request (IPFR) must be completed and submitted to WHSSC for approval prior to treatment. A partially completed copy is available by clicking here. Atypical HUS needs to be differentiated from TTP and typical HUS. This document defines the criteria for using eculizumab:

Criterion Investigation required

1. Thrombocytopaenia - Platelet count <150,000/mm or >25% Decrease from baseline

FBC

AND

2. Microangiopathic haemolysis – Schistocytes and/or Elevated LDH and/or Decreased haptoglobin and/or Decreased haemoglobin;

Blood film LDH Haptoglobin

PLUS 1 OR MORE of the following:

Renal Impairment - Elevated creatinine, decreased eGFR

Serum creatinine

Neurological Symptoms - Confusion and/or Seizures, other cerebral abnormalities

Clinical

Gastrointestinal Symptoms – Diarrhoea and/or abdominal pain

Clinical

AND

>5% ADAMTS13 activity ADAMTS 13 activity

In the absence of ADAMTS13 results, a serum creatinine >150–200 μmol/L or a platelet count >30,000 / µl almost eliminates a diagnosis of severe ADAMTS13 deficiency (TTP)

AND

Absence of a Positive Shiga-toxin/EHEC Stool for culture

Eculizumab should be initiated urgently in all patients diagnosed with aHUS. Earlier treatment with eculizumab has been associated with improved clinical outcomes. Patients treated with eculizumab require active steps to prevent meningococcal infection. Meningococcal vaccination is mandatory, before eculizumab initiation or as soon as possible if urgent eculizumab therapy is indicated. Quadrivalent conjugate vaccines (anti-A, C, Y, W) (Nimenrix or Menveo) and the anti-B vaccine if not already given. The efficacy of anti-meningococcal (vaccine) antibodies is uncertain in patients with complement deficiency, complement blockade or immunosuppressive therapy. It is therefore recommended that additional antibiotic prophylaxis is given. Which antibiotics? Penicillin V (twice daily, full dose adapted to weight).

How long? Obligatory during 2 weeks after vaccination in patients receiving eculizumab. However some experts recommend continuous antibioprophylaxis. Education should also be carried out to look out for signs of meningococcal infection facilitating early recognition and treatment. An information card should be carried by the the patient or his/her care giver, to be shown to medical staff in case of symptoms suggesting infection. Further information is available at the Renal Associaton website: http://rarerenal.org/clinician-information/haemolytic-uraemic-syndrome-atypical-ahus-clinician-information/ Monitoring of patients receiving eculizumab In addition to routine biochemistry and haematology investigations it is recommended that the following tests are carried out:

Pre dose CH50/AH50 – should be measured at least twice when the patient starts the routine long-term dose of eculizumab. Both CH50 and AH50 should show no detectable haemolytic activity. This should then be repeated annually.

Platelet count, LDH and haptoglobins – monthly

Urinalysis and PCR – monthly References Igarashi et al. Guidelines for the management and investigation of hemolytic uremic syndrome. Clin Exp Nephrol. 2014 Aug;18(4):525-57. Kaplan BS et al. Current treatment of atypical hemolytic uremic syndrome. Intractable & Rare Diseases Research. 2014; 3(2):34-45. Loirat C et al. An international consensus approach to the management of atypical hemolytic uremic syndrome in children. Pediatric Nephrology (2016) 31: 15–39. Taylor CM et al. Clinical Practice Guidelines for the management of Atypical Haemolytic Uraemic Syndrome in the United Kingdom. http://www.renal.org/docs/default-source/guidelines-resources/joint-guidelines/aHUS_Clinical_Practice_Guidelines_2009.pdf?sfvrsn=0

Appendix 1. Organising investigations.

Test Specimen Laboratory

Functional complement assays: CH50 AP50 Factor H function

Serum (SST) Serum (SST)

Biochemistry (UHW) Biochemistry (UHW) ?Newcastle

Serum levels of C3, C4, Factor H, Factor I, Factor B

Serum (SST) Biochemistry (UHW)

Genetic testing for mutation analysis in the CFH, CFI, CD46, C3 and CFB genes; Mutation analysis in THBD; Mutation analysis in DGKE; MCP (CD46) expression; Anti factor H antibodies

http://www.newcastle-hospitals.org.uk/services/northern-genetics_services_molecular-genetics_genetic-tests_haemolytic-uremic-syndrome.aspx 2 – 5 ml EDTA + one 5 ml clotted blood sample (collected into a tube with no anticoagulant or into an SST tube).

Northern Molecular Genetics Service in Newcastle upon Tyne DNA can be stored by the genetics department at UHW (EDTA samples)

C3Nef Serum (SST) Biochemistry (UHW) who send on to Sheffield

ADAMTS13 assay Citrate Haematology (UHW) Contact 42154

Coombs test EDTA Haematology (UHW) Contact 42157

Influenza studies Virology (UHW)

Cobolamin C defect Urinary Methylmalonic acid Plasma/serum methylmalonic acid Plasma homocysteine + methionine

Urine in plain universal Li heparin or serum (SST) EDTA must reach lab in 30´

Biochemistry (UHW) Biochemistry (UHW) Biochemistry (UHW)

Autoantibodies:

Anticardiolipin

Antinuclear factor

Anti double stranded DNA

Anti endonuclear

Serum (SST) Biochemistry (UHW)

Appendix 2. Explanation of functional assays. CH50 The CH50 is the most commonly used assay to screen for

complement abnormalities. Activated sheep erythrocytes (precoated with antibody) are used and mixed with dilutions of patient serum to identify the dilution required to lyse 50% of the available sheep erythrocytes. All complement components from C1 to C9 are activated. A low CH50 may result from congenital complement deficiencies, increased consumption of complement components, or insufficient synthesis of complement factors.

AP50 The AP50 is the volume of serum required to haemolyze 50% of

rabbit erythrocytes. The higher the activity of the AP, the lower the amount of serum needed to haemolyze the erythrocytes. Patients with defects in the regulatory proteins have a constitutively active AP, resulting in consumption of the AP proteins. Therefore, when laboratory testing is performed during the acute phase of the disease, the AP50 activity is often low (meaning more serum is required to induce haemolysis) because of consumption of complement cascade components.

A low AP50 activity suggests a deficiency in FB, FD, FH, or properdin. As a result, AP50 is often reduced in C3GN, DDD, and aHUS. The AP50 can also be low in Shigatoxin-producing Escherichia coli (STEC)-HUS and secondary to consumption of complement proteins from classical pathway activation. A normal C4 level and normal CH50 activity in the presence of a low AP50 activity indicates consumption confined to the AP.

Factor H function The functional test of FH uses uncoated sheep erythrocytes as

index cells. Normally, FH will bind to these cells and protect them from AP-mediated complement lysis. However, if the tested serum is from patients with FH mutations or antibodies against FH, FH function is abrogated and lysis occurs. If there is concomitant reduction in C3, FB, or both, lysis is inefficient and a false negative result can be obtained. Therefore a negative haemolytic assay must be interpreted in the context of the complete complement picture.

Checklist for initial investigations of child with suspected HUS. (File in notes) Remember that some tests may not be possible once blood products have been given.

Test Tick Date Initial

Full blood count + film

U&E’s and LFT’s

Amylase

Lactate dehydrogenase

Haptoglobin

Glucose

CRP

Coagulation Screen

Group and Save (X match if indicated)

E. coli serology (clotted sample to microbiology). Anti-LPS antibody

Stool culture

Stool – PCR for STEC virulence genes

Urinalysis

Complement studies performed by local lab:

Serum levels C3, C4

Serum levels Factor H, Factor I, Factor B

C3Nef

CH50 and AP50 activity

Complement studies which are performed by outside labs:

Autoantibodies against factor H (ensure serum sent to immunology lab to be stored)

Genetic studies (collect 5ml EDTA blood)

ADAMTS13 / Von Willebrand cleaving protease activity (Citrate specimen to coagulation lab who can then freeze)

In cases of suspected pneumococcal HUS:

Coombs’ test

Peanut lectin activity test

Pneumococcal PCR

Autoantibodies:

Anticardiolipin

Antinuclear factor

Anti double stranded DNA

Anti endonuclear

Influenza A culture, antigen detection, PCR nasopharyngeal swab or serology

Urinary/plasma Methylmalonic acid, plasma Homocysteine + methionine

Pregnancy Test (if indicated)

HIV test