Renal Manifestations in Pregnancy-Associated Thrombotic Microangiopathy (TMA)

Abstract Objective This study investigates the characteristics of pregnancy-related thrombotic microangiopathy (TMA) and its renal manifestations, with a focus on factors that affect renal prognosis. Methods Clinical data, renal involvement, treatment regimens, and prognosis were collected for patients diagnosed with pregnancy-related TMA who were admitted to the Nephrology Department of the National Center of Geriatrics at Beijing Hospital from 2014 to 2023. Results Eight clinically and/or pathologically diagnosed cases of pregnancy-related TMA were identified. The average age was (32.12 ± 5.14) years, and the onset of TMA during pregnancy occurred at an average of (28.75 ± 8.73) weeks. Common peripartum symptoms included abdominal pain, placental abruption, and postpartum hemorrhage. Causes of TMA included pre-eclampsia (PE) in 6 cases, among which 1 case was complicated by systemic lupus erythematosus (SLE) and 1 case by malignant hypertension, and atypical hemolytic uremic syndrome (aHUS) in 2 cases. Laboratory findings revealed significantly elevated levels of LDH and D-dimer, with platelet counts at (93.63 ± 86.39)×10 9 /l and hemoglobin at (75.75 ± 33.36) g/l. Renal manifestations showed varying degrees of proteinuria and hematuria in all 8 patients, with 6 patients experiencing different degrees of renal impairment and 2 patients showing no renal function impairment. The highest serum creatinine recorded was (366.58 ± 275.06) umol/l, with 2 cases of aHUS patients requiring renal replacement therapy and 4 patients (2 cases of aHUS patients, 1 case of PE patient, and 1 case of PE combined with SLE patient.) needing plasma exchange treatment (≥ 1time). Among the 6 patients who underwent renal biopsy, 50% exhibited glomerular capillary endothelial cell swelling (83.3%), capillary lumen opening disparity (66.7%), small vessel endothelial cell swelling (66.7%), or brush border loss of renal tubules (66.7%). Four cases of patients had electron microscopy results: 1 case showed endothelial cell proliferation and segmental widening of the basal membrane's loose layer; 1 case showed a large number of fragmented red blood cells within the capillary loops; and 2 cases did not exhibit typical TMA electron microscopy findings. Comparisons between aHUS and PE groups revealed significant differences in serum creatinine levels and the proportion of patients requiring renal replacement therapy (P < 0.05). Patients with aHUS tended to develop the condition later in pregnancy and also had lower platelet counts. Prognosis results showed that 1 patient remained on hemodialysis, 1 patient came off dialysis, 1 patient was discharged automatically, and 3 patients exhibited a significant decrease in serum creatinine upon discharge among the 6 patients with kidney function impairment. Conclusion Pregnancy-related TMA mostly manifests in mid to late pregnancy, with PE being the most common cause and renal manifestations primarily presenting as proteinuria, hematuria, and acute renal failure. Furthermore, patients with pregnancy-related aHUS tend to develop the condition later in pregnancy, experience more severe renal function impairments, have lower platelet levels, and require renal replacement therapy at a higher rate. Once diagnosed with aHUS as the cause of pregnancy-related TMA, promptly terminating the pregnancy and actively engaging in plasma exchange treatment may improve prognosis.