Anemia and idiopathic intracranial hypertension: a prospective study

Background: Anemia has been temporally associated with idiopathic intracranial hypertension (IIH), but the relationship is uncertain because of a lack of prospective studies and because both IIH and anemia are common in young women with obesity. Design and methods: This was a prospective study of consecutive patients with IIH referred to 3 neuro-ophthalmology centres between March 2021 and September 2022. All patients had a complete blood count available within 6 months of presentation. Anemia was defined as mild (110-120 g/L), moderate (80-109 g/L), and severe (<80 g/L). Results: Of 143 patients, 113 had normal hemoglobin (group 1) and 30 had anemia (group 2). In group 2, the anemia was defined as mild (15 of 30; 50.0%), moderate (11 of 30; 36.7%), and severe (4 of 30; 13.3%). There was no difference in female sex (105 of 113 vs 29 of 30; p = 0.453), age (31.5 f 9.2 years vs 28.5 f 10.3 years; p = 0.144), and body mass index (35.2 f 6.9 kg/m2 2 vs 38.0 f 8.1 kg/m2; 2 ; p = 0.111). Groups 1 and 2 did not differ in visual acuity (0.04 f 0.09 logMAR vs 0.07 f 0.14 logMAR; p = 0.377), retinal nerve fibre layer thickness (174.5 f 68.4 mu m vs 206.5 f 97.0 mu m; p = 0.098), mean deviation (-3.2 f 3.1 dB vs -3.9 f 3.4 dB; p = 0.180), and the need for medical (34 of 113 vs 8 of 30; p = 0.715) or surgical treatment (3 of 113 vs 3 of 30; p = 0.074). Patients with moderate to severe anemia were more likely to require surgical therapy (2 of 15 vs 3 of 113; p = 0.045). Conclusion: Approximately 1 of every 5 patients with IIH has anemia, and this is severe in >10% of patients. Patients with moderate and severe anemia may require more invasive surgical treatment. Given the high incidence of anemia and the availability of a complete blood count, we recommend that this test be obtained for all patients with suspected IIH.