WASHINGTON, DC – Acute kidney injury (AKI) is a rare but morbid complication of pregnancy, presenters said during Kidney Week 2019. Cases are rising in developed countries including the U.S., though, and understanding anatomic and physiologic changes is critical to understanding the diagnosis.

The number of obstetric AKI cases in the U.S. is on the increase, said Vesna D. Garovic, MD, PhD, a nephrologist with the Mayo Clinic in Rochester, Minn. A study¹ of 11 million deliveries found these cases rose from 2.4 per 10,000 pregnancies in 1999-2001 to 6.3 per 10,000 pregnancies in 2010-2011, at a 10% yearly increase.

Several factors are contributing, Garovic said, including an increase in detection of AKI thanks to changes in coding practices, and advanced maternal age. Modern fertility techniques that facilitate pregnancies in women with conditions such as diabetes, hypertension and polycystic ovary syndrome also impose risks for AKI. And, AKI is particularly pronounced in women with preeclampsia, potentially due to an increase in the incidence of hypertensive disorders of pregnancy.

There is a challenge in defining AKI in pregnancy, said Ursula C. Brewster, MD, an associate professor of medicine at Yale School of Medicine in New Haven, Conn., because a number of hemodynamic and anatomic changes occur even in normal pregnancies, when the kidney grows in size. Remember that patients’ creatinine levels should go down: “If somebody has a creatinine of 0.8 mg/dL when they go into being pregnant and all of a sudden they’re at 1.1, that’s a pretty significant AKI because they should be down around 0.4/0.5.”

Thrombotic microangiopathies may look similar but are different and require different treatment strategies, Brewster noted. She offered tips to manage patients with these conditions:

Thrombotic thrombocytopenic purpura (TTP) – Patients with suspected or confirmed TTP should be started on plasma exchange. Her team usually exchanges 1.5 plasma volumes for the first three days, and continues until platelet counts stabilize. Explain to your pheresis team that you need them to replace with cryoprecipitate or fresh frozen plasma, not albumin.

These patients also should be given steroids, such as pulsing with 1 gm of methylprednisone for three days. There has been some talk about giving rituximab but the data “is not terribly robust” regarding safety, Brewster said, so it should be a last resort. During subsequent pregnancies, patients should be managed prospectively with plasma infusions or at least monitored closely as they get toward the end. It’s also important to continue therapy into the postpartum period as relapse is common.

Atypical hemolytic uremic syndrome (aHUS) – Eculizumab is the preferred treatment for this condition but because of its expense, decide within your institution how to get it quickly when you need it. Eculizumab should be started as quickly as possible in a weekly infusion. The duration of treatment is still murky but should be for at least eight to 10 weeks.

Patients receiving the drug need to be immunized for meningococcus and will need antibiotics against encapsulated organisms, Brewster added. For subsequent pregnancies, consider giving the drug prophylactically. “It really has changed how we treat these women, which for so long has been catastrophic.”

If you’re unsure if the patient has TTP or aHUS, always start them on plasmapheresis until you know.

Lupus glomerulonephritis – This can occur for the first time during pregnancy or postpartum as the immune system reconstitutes, and patients who had lupus before may be at increased risk for a flare during pregnancy. Make sure to have an anti-Ro antibody in these women because of the association with congenital and fetal heart block.

It’s important to get baseline data such as CBC counts and urine protein to understand the lupus status early in pregnancy, Brewster said. A kidney biopsy is essential for diagnosis. Prevention efforts include giving anticoagulation drugs for antiphospholipid syndrome, low-dose aspirin to prevent preeclampsia, and controlling blood pressure.

If patients have a lupus flare, you don’t have to deliver the babies, you can just treat them and see how they do. Immunosuppression drugs safe to give include prednisone, azathioprine and calcineurin inhibitors. There is unknown safety with some of the biologics such as rituximab or belimumab. If patients are anti-Ro positive and you are concerned about fetal heart block, there is some evidence that dexamethasone crosses over the placenta and may be a better drug.

Resource

1. Mehrabadi A, Dahhou M, Joseph KS, Kramer MS. Investigation of a Rise in Obstetric Acute Renal Failure in the United States, 1999-2011. Obstet Gynecol. 2016 May;127(5):899-906. doi: 10.1097/AOG.0000000000001374.