Microcytic or Iron Deficiency Anemia as a Risk Factor for Cerebral Sinus Venous Thrombosis—Systematic Review and Exploratory Meta-analysis

Abstract

Background Cerebral sinus venous thrombosis (CSVT) is a rare but severe neurological condition. Iron deficiency anemia (IDA) has been suggested as a risk factor. Recent experimental data in iron-deficient rodents show a potential pathophysiological link between IDA and increased thrombus formation, resulting from iron-restricted erythropoiesis. Given the high prevalence of IDA, understanding its role in CSVT is of major clinical interest.

Methods We conducted a systematic review and exploratory meta-analysis, searching PubMed and Embase up to January 30, 2026, for original English-language articles investigating iron deficiency (ID), anemia, or IDA as risk factors for CSVT. The review followed PRISMA guidelines and assessed evidence quality using the Cochrane GRADE approach. The study was registered on PROSPERO (CRD42020205229).

Results A total of 62 studies comprising 2,877 patients met inclusion criteria, including four case–control studies, 18 case series, and 40 case reports. Reported odds ratios ranged from 1.1 to 4.4 in adults and 3.8 to 11.4 in pediatric studies. Exploratory meta-analysis yielded pooled ORs of 2.55 (95% CI: 0.89–7.33) in adults and 4.39 (95% CI: 1.16–16.57) in children. Both estimates were based on only two studies each, with limited sample sizes and substantial uncertainty. The pediatric estimate warrants particular caution, as some studies combined CSVT with other cerebrovascular outcomes. Overall, the included studies suggested an association between anemia and CSVT, although the certainty of evidence was low.

Conclusion Current evidence suggests a possible association of severe or microcytic anemia, indicating IDA, and an increased CSVT risk. However, available data are limited, heterogeneous, and largely observational, precluding conclusions on causality or precise effect sizes. These findings support heightened clinical awareness of IDA in CSVT patients and highlight the need for prospective population-based studies to determine whether IDA prevention or treatment reduces thrombotic risk.