The Relationship between Protoporphyrin IX and Platelet Count in the Protoporphyrias

• Published in: Blood 2023-11, Vol.142 (Supplement 1), p.5230-5230
• Main Authors: Leaf, Rebecca Karp, Jiang, Paul Yanning, Goddu, R. Jay, Tran, Benny, Rebeiz, Lina, Elmariah, Sarina, Hodges, Pamela G, Mead, Jennifer, Trinidad, John, Saberi, Behnam, Fleming, Mark D., Ducamp, Sarah, Anderson, Karl, Dickey, Amy
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2023-180928

Introduction: Erythropoietic protoporphyria and X-linked protoporphyria, collectively known as the protoporphyrias, are inherited disorders of heme biosynthesis characterized by the accumulation of protoporphyrin IX in the skin and other organs. Clinical manifestations include severe pain with exposure to sunlight, as well as liver disease in a subset of patients. Approximately half of patients with protoporphyria have mild microcytic anemia, which is not well understood but thought to be related either to decreased iron availability or to decreased heme biosynthesis. Several reports have described mild thrombocytopenia in patients with protoporphyria (Delaby et al., 2009, Wensink et al., 2022), although thrombocytosis would be expected with iron deficiency as low iron biases megakaryocyte-erythroid progenitors to the megakaryocyte lineage (Xavier-Ferrucio et al., 2019). We sought to further characterize the relationship between erythrocyte metal-free protoporphyrin IX (PPIX) levels, platelet count, and iron status in patients with protoporphyria. Methods: We conducted a single-center cohort study of adults with protoporphyria treated at the Massachusetts General Hospital Porphyria Center from March 2021 through June 2023. Patient-level data across multiple time points were collected, including platelet count, ferritin, and alanine transaminase (ALT). Generalized Estimating Equation (GEE) models with an identity link and gaussian family distribution were performed to determine the association, accounting for within-participant associations. Results: A total of 38 patients with protoporphyria were included in the analysis. The median PPIX level was 1169.5ug/dl (interquartile range [IQR] 729.50 - 2069.75, reference range