Natriuretic pro-peptides in idiopathic intracranial hypertension

Idiopathic intracranial hypertension is a disorder of unknown pathogenesis. Natriuretic peptides may be involved in intracranial pressure regulation, but cerebrospinal fluid (CNS) and plasma concentrations in this disorder are unknown. We evaluated venous and intrathecal concentrations of ANP, BNP and CNP precursor peptides in 40 patients with idiopathic intracranial hypertension and in 20 controls. Natriuretic pro-peptides were quantitated using processing-independent assays. In CSF, no differences in peptide concentrations between patients and controls were found (proANP: 239 + or - 23 vs 231 + or - 22 pmol/L, proBNP: <2 pmol/L in all, proCNP: 1079 + or - 318 vs 1138 + or - 323 pmol/L). In plasma, proCNP was lower in IIH compared with controls (35.3 + or - 4.8 pmol/L vs 43.8 + or - 5.9 pmol/L, p<0.0001). Moreover, plasma proBNP was significantly lower in patients compared with controls (47.1 + or -21.4 pmol/L vs 59.2 + or - 22.0 pmol/L, p = 0.045). There were no associations between peptide concentrations and ICP and BMI, respectively. Plasma proANP and proCNP increased during 3 months follow-up (p=0.01 and p=0.006), n=12. We suggest that decreased plasma proCNP concentration in idiopathic intracranial hypertension may reflect endothelial dysregulation of vascular tone and may be a marker in this disease. Further studies of proCNP and endothelial function are needed to establish such role.