Background Renal involvement in antiphospholipid syndrome (APS) is still relatively unknown and probably underestimated. The main lesions consist of renal artery stenosis (RAS), venous renal thrombosis, and glomerular lesions. The resistive index (RI) of intra-renal arteries, indicating vascular resistance, has been evaluated in different nephropathies showing an association with functional parameters and histological features. Nonetheless, there are no studies in patients with APS.
Objectives We aimed to evaluate the renal arteries RI, by color-Doppler ultrasonography (US), in a group of patients affected by APS.
Methods We enrolled patients with primary APS (PAPS-Sapporo revised criteria), patients with APS secondary to Systemic Lupus Erythematosus (SAPS-1997 ACR criteria) and subjects positive for antiphospholipid antibodies without clinical manifestations (aPL-carriers). All patients underwent clinical assessment (anamnestic data and traditional risk factors for cardiovascular disease), and laboratory evaluation (anti-cardiolipin, anti-β2 glycoprotein I, lupus anticoagulant, C3 and C4 serum levels). US Doppler assessment was performed, RI>0.7 was considered pathologic.
Results We enrolled 11 patients with PAPS, 22 patients with SAPS and 11 aPL-carriers. The clinical and laboratory features are described in Table. Pathologic RI was detected in 27.3% of SAPS patients compared to 9.1% of PAPS and aPL-carriers (P=NS). A significant correlation between the mean RI and the presence of hypertension (Spearman's test P<0.001, r=0.838) and diabetes (P<0.001, r=0.861) was observed in PAPS patients. Interestingly, RAS was observed only in patients with PAPS (3/11, 27.3%) and in none of SAPS and aPL-carriers. Finally, the presence of stenosis was not associated with a pathologic RI.
Conclusions We evaluated for the first time the intra-renal artery RI in APS patients: a pathological RI was detected mostly in SAPS patients. Conversely, RAS was detected only in PAPS patients. These results could suggest a different diathesis in the pathogenesis of the renal vascular manifestations in patients with APS.
Disclosure of Interest None declared
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