Blood disease helps trigger aHUS after childbirth in woman in rare case
Close monitoring urged for affected patients, as condition may be 'sensitizing'
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A young Asian woman with a genetic blood disease developed atypical hemolytic uremic syndrome (aHUS) after childbirth, leading clinicians to treat the rare case with hemodialysis, in which machines are used to clean a person’s blood, and supportive care.
The researchers reported that the woman, who was living with a blood condition called beta-thalassemia intermedia, bled heavily after giving birth. That appeared to trigger aHUS — in which clots form in small blood vessels — leading to a drop in kidney function for the new mother, according to the team.
With treatment starting within days, the woman’s condition improved, and her kidney function fully recovered within three months, the researchers noted.
The team concluded that “thalassemia should be considered a potential sensitizing condition” for aHUS occurring after childbirth, “warranting close monitoring and … evaluation in such patients.”
The woman’s case was described by three researchers in China in a report titled “Postpartum Atypical Hemolytic Uremic Syndrome Complicating [Beta]-Thalassemia Intermedia: A Case Report and Literature Review,” which was published in the Journal of Clinical Medicine.
In aHUS, the complement system, part of the body’s immune system, becomes overly active and causes blood clots to form in small blood vessels, which can damage organs. While certain genetic mutations can predispose a person toward aHUS, a trigger is typically necessary for symptoms to develop.
One common trigger for aHUS is pregnancy, with complications such as heavy bleeding further contributing to an overactive complement system.
New mother lived with blood condition thalassemia
In this case, a 27-year-old woman in the Chengdu area had been diagnosed with beta-thalassemia intermedia, a condition in which the body does not make enough normal hemoglobin, the protein that carries oxygen in red blood cells. Beta-thalassemia intermedia can cause moderate hemolytic anemia, meaning red blood cells are destroyed faster than normal. It can also reduce levels of proteins that normally protect red blood cells from the complement system.
The woman became pregnant and, during pregnancy, needed blood transfusions every 4-6 weeks to keep her hemoglobin stable.
She delivered her baby vaginally at full term. Soon afterward, she developed uterine atony, meaning the uterus did not contract properly after delivery, as well as a vaginal wall hematoma, which is a collection of blood in the tissues. She had heavy bleeding and needed transfusions to replace lost blood.
Within hours, her urine output fell sharply, and her kidney function worsened. Over the next several days, her hemoglobin and platelets dropped to very low levels, while lactate dehydrogenase, which is released into circulation when red blood cells are destroyed, increased. A blood smear showed schistocytes, which are fragmented red blood cells.
These findings indicated microangiopathic hemolytic anemia, meaning red blood cells were being mechanically destroyed in small blood vessels. The combination of anemia, low platelets, and acute loss of kidney function suggested a thrombotic microangiopathy, in which blood clots form in small blood vessels and damage organs.
Several tests helped identify the cause. ADAMTS13 activity was normal at 90%, making thrombotic thrombocytopenic purpura, a type of thrombotic microangiopathy, unlikely. A complement test showed activation of the final part of the complement system.
Researchers suggest ‘3-hit mechanism’ was at work
With the testing, a “diagnosis of [pregnancy-associated] aHUS was confirmed,” the team wrote.
The woman’s treatment involved supportive care and hemodialysis, a procedure that filters waste and excess fluid from the blood when the kidneys cannot adequately perform that function. Soliris (eculizumab), an antibody approved for aHUS that works by inhibiting complement activation, was not available at the hospital, so it could not be used, the researchers noted.
Hemodialysis began on the fifth day after delivery. According to the team, the woman’s platelets and kidney function gradually improved, and she was discharged about two weeks after giving birth. Three months later, her creatinine, a marker of kidney function, showed that her kidneys had recovered, the researchers noted.
[The blood disease thalassemia] may contribute to the development of [pregnancy-associated] aHUS.
The researchers noted that “prior reports have suggested a potential link between thalassemia and aHUS, but the mechanistic evidence has remained indirect.” The team concluded that the blood disease, when combined with childbirth complications, “may contribute to the development of [pregnancy-associated] aHUS.”
“These findings indicate that thalassemia is not an incidental [coexisting disease] but a complement-sensitizing condition,” the researchers wrote.
In this case, the team suggested a “three-hit mechanism.” Specifically, beta-thalassemia intermedia may have predisposed the woman toward complement activation, with pregnancy adding another stress on the complement system, and heavy bleeding acting as the final trigger for aHUS.
The researchers called for future studies to “evaluate the incidence of aHUS” in pregnant people with thalassemia. Further, the team urged close monitoring for such patients during pregnancy.
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