α-1 Microglobulin as a New Inflammatory Marker in Newly Diagnosed Hypertensive Patients

Background The α-1 microglobulin (A1M) is considered to be a marker of renal insufficiency, suggesting disturbed tubular function. In the present study we examined the ability of urinary A1M excretion to reflect the overall inflammatory status in patients with newly diagnosed essential hypertension and normal renal function. Methods The study population consisted of 1445 nondiabetic patients with newly diagnosed arterial hypertension and no evidence of renal insufficiency. Serum levels of C-reactive protein (CRP), serum amyloid α (SAA), and plasma fibrinogen, as well as urinary A1M excretion, were estimated. Multivariate analysis was performed to evaluate the associations between hypertension; A1M urinary excretion; and circulating levels of CRP, SAA, and fibrinogen. Results Patients with systolic hypertension had higher CRP, SAA, fibrinogen, and A1M compared with patients with isolated diastolic hypertension (P< .0001 for all). In multivariate analysis, systolic (but not diastolic) blood pressure (BP) was independently associated with A1M, CRP, and SAA (P< .0001 for all), whereas urinary A1M was also independently correlated with inflammatory markers such as CRP (P = .0001) and SAA (P = .0001). Conclusions Urinary A1M is independently associated with circulating acute phase proteins in patients with newly diagnosed hypertension, whereas it is closely associated with systolic but not diastolic BP. Our findings suggest that urinary α-1 microglobulin may reflect the overall inflammatory status in patients with newly diagnosed essential hypertension, beyond its value as a marker of renal function.