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Hemolytic-Uremic Syndrome (HUS) in Children

by Brian Alverson, MD
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    00:02 In this lecture, we’re going to review hemolytic-uremic syndrome in children.

    00:07 Hemolytic-uremic syndrome is a combination of a few different findings.

    00:11 These patients have a microangiopathic hemolytic anemia.

    00:16 They’ll have acute kidney injury and they will have thrombocytopenia.

    00:21 So anemia and thrombocytopenia as well as kidney injury.

    00:28 This disease typically happens in children under five years of age and it’s the most common cause of acute kidney injury in children.

    00:38 If it’s preceded by diarrhea, the mortality if fairly low, 4%.

    00:45 Although, those odds aren’t what you would like for your own child.

    00:49 If it’s not preceded by diarrhea, the mortality is high, 25%.

    00:57 So the diarrhea versus no diarrhea is an important thing to understand right off the bat.

    01:03 What we call D positive or D plus, diarrhea-induced hemolytic-uremic syndrome is the majority of cases, about 90%.

    01:15 And of those, we usually see the culprit as E. coli O157:H7.

    01:22 Alternatively, patients may have Shigella dysenteriae type 1, but the idea here is there’s a bacterial cause to their diarrhea resulting in a toxin which causes the patient to go into hemolytic-uremic syndrome.

    01:38 We typically see patients getting E. coli O157 from undercooked meats, unpasteurized milk, unwashed fruit and vegetables or petting zoos.

    01:51 We tend to see little outbreaks happen sometimes from petting zoos where that bacteria has become prevalent and patients are perhaps not cleaning their hands appropriately after petting the farm animals.

    02:05 Diarrhea negative or D minus HUS is often caused by Strep pneumoniae infections especially if there is pleural effusion, but this is rare.

    02:17 So in a large study at the Children’s Hospital of Philadelphia, they looked at many decades and they only found a handful of cases, but in those cases, usually from patients who had complicated pneumonia with pleural effusions.

    02:31 Another possible cause of D negative HUS is certain medication such as cyclosporine or tacrolimus.

    02:39 Also HIV can cause the problem and so we might see this in patients with HIV.

    02:46 There are some very rare causes of non-infectious hemolytic-uremic syndrome.

    02:51 An example would be inherited Von Willebrand’s factor deficiency or patients who have vitamin B12 metabolism disorders or other rare family disorders.

    03:03 Likewise, patients may have secondary non-infectious hemolytic-uremic syndrome.

    03:09 For example, a patient who has microvascular injury from the vasculitis associated with lupus or patients who have clots from antiphospholipid antibody syndrome or patients with, say, malignant hypertension.

    03:24 But these causes are rare and we should really focus on D positive or diarrhea positive HUS.

    03:32 So D positive HUS is typically an illness where it starts with a bloody diarrhea.

    03:40 Patients may have vomiting and fever with the acute illness from the usually E. coli O157.

    03:48 This diarrhea may resolve or it may still be present when the new symptoms occur.

    03:54 And the new symptoms will be an acute onset of lethargy, irritability and key, pallor.

    04:01 These patients will develop oliguria.

    04:04 They’re developing oliguria because their kidneys are shutting down.

    04:09 They may have neurologic syndromes present as well such as altered mental status or seizure.

    04:16 The point is that these children can be very sick.

    04:20 Ten percent of them can go into congestive heart failure.

    04:23 They can have all kinds of substantial problems and we have to watch them very carefully.

    04:29 Here is an example of what a slide might look like if you were to look at the blood of a patient with hemolytic-uremic syndrome.

    04:35 They will have schistocytes or other evidence of a normocytic anemia, however, there will be evidence of the microangiopathic nature of this anemia.

    04:47 Remember, these cells are being viciously split apart inside the blood vessels.

    04:53 Additionally, patients typically have a low platelet level, usually between 20-100,000 platelets.

    05:01 This is because, again, of a consumptive coagulopathy.

    05:07 In patients with hemolytic-uremic syndrome, the Coombs test should be negative.

    05:12 This is not an antibody mediated disease.

    05:14 These cells are being broken apart because it’s a microangiopathic state.

    05:19 A urinalysis will show hematuria and proteinuria.

    05:24 Additionally, we may get a Chem 7.

    05:27 The Chem 7 will show a high BUN and creatinine consistent with intrarenal disease.

    05:33 If it’s severe, the patient may have high potassium from renal failure or cell lysis in combination from renal failure.

    05:42 And because of their hemolysis, patients will have a high LDH and often a high indirect bilirubin and may be frankly jaundiced.

    05:51 In patients with hemolytic-uremic syndrome, they have a bloody diarrhea caused by E. coli 0157:H7.

    06:00 It may be tempting to give them antibiotics to treat that E. coli and to think that, that might prevent the hemolytic-uremic syndrome.

    06:08 On the contrary, it seems that treatment may, in some patients, actually increase risk of HUS.

    06:15 So we do not treat patients with antibiotics in this condition.

    06:21 What we will do is treat people symptomatically for their problems.

    06:25 First, we need to be very careful with fluid and electrolyte management.

    06:29 Remember, we’re trying to maintain a situation where the child is remaining hydrated and yet in the child, there may be some renal failure.

    06:38 Also, a high potassium is an emergency because patients may have arrhythmias so we have to keep an eye on that potassium.

    06:47 Close monitoring of both fluid and electrolytes is absolutely indicated.

    06:52 If patients end up in trouble, we may have to do dialysis to try to control levels of electrolytes and the fluid in the blood.

    07:01 We also want to control their hypertension.

    07:04 We can’t let that get out of control and we may provide medications for that purpose.

    07:08 If patients are seizing, we need to control the seizures as well and we’ll provide seizure medications.

    07:16 It’s important to transfuse children if they are symptomatic and have tachycardia.

    07:22 We usually try to keep them above approximately the level of 7, but do not transfuse platelets.

    07:29 It will be rare for these children to get into a trouble zone, say, less than five to ten thousand and the platelets almost immediately get consumed.

    07:38 So it will just worsen the coagulopathic state.

    07:42 Overall for HUS, the mortality is generally less than 5% as we said before, especially for the diarrhea positive disease.

    07:52 However, some patients progress to end-stage renal disease and may eventually need a transplant.

    07:58 The key thing here is that we have to promote hand washing and safe processing of foods and certainly hand washing when visiting the petting zoo.

    08:08 That’s the summary of hemolytic-uremic syndrome.

    08:11 Thanks for your attention.


    About the Lecture

    The lecture Hemolytic-Uremic Syndrome (HUS) in Children by Brian Alverson, MD is from the course Pediatric Nephrology and Urology. It contains the following chapters:

    • HUS
    • Diarrhea Negative HUS
    • HUS – Diagnosis

    Included Quiz Questions

    1. Farm animals
    2. Dogs
    3. Daycare facility
    4. Other patients with diarrhea
    5. Blood transfusions
    1. E. coli disease
    2. Cyclosporine use
    3. Inherited Von Willebrand’s factor deficiency
    4. SLE
    5. Anti-phospholipid antibody syndrome
    1. HUS with diarrhea is more common comparatively.
    2. HUS with preceding diarrhea has more mortality.
    3. HUS not preceding with diarrhea have a mortality of 4% only.
    4. HUS with diarrhea spreads through blood transfusion.
    5. HUS without diarrhea is caused by E. coli.
    1. S. pneumonae
    2. E. coli
    3. S. aureus
    4. Salmonella typhi
    5. Neisseria
    1. Coombs positive microcytic anemia
    2. ARF
    3. ESRD
    4. Seizures
    5. Hyperkalemia

    Author of lecture Hemolytic-Uremic Syndrome (HUS) in Children

     Brian Alverson, MD

    Brian Alverson, MD


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