Anemia and Idiopathic Intracranial Hypertension: A Case-Control Study.

Background: Idiopathic intracranial hypertension (IIH) is a condition that mostly affects obese women of childbearing age but has been reported to be temporally related to new diagnoses of anemia. Despite these reports, the association between anemia and IIH remains controversial. The present study aimed to understand the strength of association between anemia and IIH through a case-control design.

Methods: Consecutive IIH patients were recruited from neuro-ophthalmology clinics and matched by age and sex to consecutive patients attending neuro-ophthalmology clinics with diagnoses other than IIH. Complete blood counts (CBCs) were reviewed within 6 months of neuro-ophthalmology presentation, and anemia was diagnosed by hemoglobin of <120 g/L in women and <130 g/L in men. Anemia was classified as microcytic (mean corpuscular volume (MCV) < 80 fL), normocytic (MCV 80-100 fL), and macrocytic (MCV > 100 fL) as well as mild (hemoglobin >110 g/L), moderate (hemoglobin 80-109 g/L), and severe (hemoglobin <80 g/L).

Results: One hundred twenty-three IIH patients and 113 controls were included in the study. More IIH patients than controls had anemia (22.8%, 28/123 vs 10.6%, 12/113, P = 0.01) with an odds ratio of 2.48 (95% CI: 1.19, 5.16). There were no differences in severity of anemia or MCV between IIH patients and controls, with anemia most often being mild (57.1%, 16/28 vs 75%, 9/12) and normocytic (50.0%, 14/28 vs 50.0%, 6/12). However, 17.9% (5/28) of IIH patients had severe anemia compared with zero in the control group. IIH patients had a higher mean platelet count than controls ( P < 0.001), and there were no differences on leukocyte counts.

Conclusion: Idiopathic intracranial hypertension patients have a higher prevalence of anemia compared with non-IIH neuro-ophthalmology patients. The anemia was mostly mild and may be explained by other factors related to worse health status and obesity, including low socioeconomic status, poor nutrition, and polycystic ovary syndrome. However, as a CBC is a widely available test and anemia may influence the IIH disease course, we propose that this test be obtained in all patients with new papilledema.