Vitamin D deficiency increases stroke risk but there are limited data in relation to underlying stroke etiology. We examined the association of serum 25-hydroxyvitamin D (25-OHD) and stroke etiology in 144 Asian ischemic stroke patients (41% small artery, 14% large artery, 9% cardioembolic, 1% other and 35% undetermined etiology by TOAST classification). Serum 25-OHD was measured using Roche competitive electrochemiluminescence immunoassay from blood samples taken within 1 week of stroke.
The majority had vitamin D insufficiency (50–100 nmol/L) (55%) or deficiency (<50 nmol/L) (40%). Patients with large versus small artery stroke had lower median serum 25-OHD (48·4 nmol/L, IQR 38·6–59·4 vs. 61·8 nmol/L, IQR 40·2–77·8, P = 0·074) and higher vitamin D deficiency prevalence (60% vs. 36%, P = 0·057). After adjusting for age, gender, hypertension, hypercholesterolemia, diabetes, atrial fibrillation, smoking and ischemic heart disease, patients with large artery stroke had lower serum 25-OHD (P = 0·002) and were 3·5 times more likely to have vitamin D deficiency compared to small artery stroke patients (P = 0·022).
This is the first cross-sectional study comparing serum 25-OHD between ischemic stroke etiologies. Our findings may be explained by a stronger relationship between vitamin D deficiency and large artery stroke. Alternatively, small cerebral arteries may be more susceptible to vitamin D deficiency as suggested in a case-control study of healthy female nurses showing a higher risk of small artery stroke among patients with lowest versus highest tertiles of serum 25-OHD, but no associated risk of large artery stroke . Longitudinal studies are needed to better understand the differential relationship between vitamin D deficiency and stroke etiologies. Furthermore, the benefit of vitamin D replacement may differ for large and small artery stroke prevention.