Blood pressure spike triggers aHUS-like symptoms in girl, 7

Difficult diagnosis since aHUS usually leads to high blood pressure in children

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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In a young girl, thrombotic microangiopathy — a group of disorders, including atypical hemolytic uremic syndrome (aHUS), that are marked by organ damage caused by the formation of blood clots inside small blood vessels — occurred secondary to a sudden spike in blood pressure.

Because the opposite is more common in aHUS, this made her diagnosis challenging for doctors.

The girl’s case was described in a study, “What came first, atypical hemolytic uremic syndrome or malignant hypertension: a clinical dilemma,” that was published as a letter to the editor in the journal Renal Failure.

aHUS is caused by the uncontrolled activation of the complement system, a part of the immune system. This causes blood clots to form inside small blood vessels, which can damage the body’s internal organs, particularly the kidneys.

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Severe hypertension is one of my most challenging aHUS symptoms

Common to see high blood pressure in children with aHUS at disease onset

It’s common for children with aHUS to have high blood pressure at disease onset. Now, researchers in India and the U.S. have reported the case of a young girl in whom a hypertensive crisis, or a sudden, severe increase in blood pressure, triggered thrombotic microangiopathy.

The seven-year-old girl, previously healthy, was admitted to the hospital with abdominal pain, nausea, vomiting, and weakness lasting 15 days, or about two weeks. She appeared pale and had high blood pressure (204/118 millimeters of mercury).

A fundus examination of the inside of her eyes revealed severe hypertensive retinopathy, or damage to the small blood vessels of the light-sensitive tissue at the back of the eyes caused by high blood pressure, along with swelling and fluid buildup.

“Given her symptoms and presence of severe hypertension, the possibility of a hypertensive crisis, with end-organ damage was considered,” the researchers wrote.

Blood workup revealed high numbers of immature red blood cells and the presence of schistocytes, or red blood cell fragments, consistent with red blood cell destruction. Levels of lactate dehydrogenase, a marker of tissue injury, were also higher than normal.

The girl’s blood levels of a waste product called creatinine were also higher than normal, a sign that her kidneys might be damaged. These findings suggested thrombotic microangiopathy with kidney damage. 

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Soliris Effective in aHUS Patients With or Without High Blood Pressure

Girl started treatment with Soliris, blood pressure medications

Although genetic testing for complement abnormalities came back negative, the girl was started on Soliris (eculizumab), a complement inhibitor approved for aHUS, and antihypertensives to reduce blood pressure. Her blood pressure gradually lowered over the course of two days.

Further examination revealed left ventricular hypertrophy, or an enlargement of the heart’s left lower chamber, and vesicoureteral reflux, which occurs when urine flows backward from the bladder up to the kidneys.

This led doctors to suspect malignant hypertension, which occurs when a sudden spike in blood pressure puts a person at risk of developing organ damage and loss of function.

“Our patient had no prior history of hypertension but had signs of hypertensive end-organ changes … leading to malignant hypertension-associated thrombotic microangiopathy,” the researchers wrote.

“This case was challenging to diagnose because standard tests for complement abnormalities did not show abnormalities despite symptoms resembling atypical hemolytic uremic syndrome,” they wrote.

The team also noted it “is rare to find thrombotic microangiopathy secondary to an uncontrolled hypertension due to an underlying reflux nephropathy [loss of kidney function] and chronic kidney disease in a child.”

“In our case, severe uncontrollable hypertension appeared to trigger complement activation,” they wrote, noting the girl responded well to treatment with Soliris and thrombotic microangiopathy didn’t return after she stopped treatment.