Anemia in patients undergoing chronic therapeutic plasma exchange.

Therapeutic plasma exchange is known to be an extracorporeal treatment procedure with few adverse effects. Anemia in chronically exchanged patients is not a well-recognized adverse effect. Our aim is to find if adult patients develop anemia while undergoing prolonged TPE treatments and to determine the time of onset of anemia. We retrospectively reviewed all outpatients that have undergone TPE at least once a week from July 2017 to March 2020. Kaplan-Meier time-to-event analysis was employed to calculate the time taken for development of anemia and time to reduction of hemoglobin by 1 g/dL from baseline in uncensored patients. A total of 14 patients met inclusion criteria receiving chronic TPE for neurological disorders including myasthenia gravis (MG). Eleven patients had once a week procedure. Study patients underwent a total of 113 (IQR, 84-227) TPE procedures and the duration of TPE was 4 (IQR, 2-6.5) years. Anemia was prevalent in 29% of this patient cohort before the initiation of TPE with a median hemoglobin of 9.4 (IQR, 8.1-11.0) g/dL. All patients regardless of hemoglobin levels prior to therapy had a decrease of 1 g/dL in hemoglobin in 6 (IQR, 3-8) weeks after initiation of chronic TPE. Anemia occurred in all non-anemic patients who underwent chronic TPE within a short period of ten weeks. Patients who were moderately anemic prior to initiation of TPE progressed to severe anemia within six weeks of TPE. Our results suggest that anemia is a consequence of chronic TPE. Baseline and follow-up laboratory studies are vital for early diagnosis.