['Blood pressure (BP) affects hypertensive left ventricular mass (LVM), explaining 10-25% of its variation. Thus, it is plausible that other factors operate in this process. Reduced kidney function is associated with increased LVM.', 'We enrolled 1000 untreated hypertensives with serum creatinine ≤ 1.5mg/dL and without proteinuria. BP was measured by standard sphygmomanometer. LVM was calculated with the Devereux formula and indexed by body surface area (LVMI). Anthropometric and the following laboratory parameters were measured: plasma glucose, serum insulin, cholesterol, triglyceride, creatinine and e-GFR (CKD-EPI equation).', 'On univariate analysis, both insulin (r=0.44, P<0.0001) and creatinine (r=0.37, P<0.001) were directly related to LVMI. In multivariate regression analysis insulin resulted the first factor in rank explaining the variability in LVMI (semipartial r=0.34,P<0.001), followed by creatinine. Fasting insulin interacts with creatinine in explaining LVM variability: 0.1mg/dL increase in creatinine produces an increase of 8.1g/m(2) in LVMI in patients with higher plasma insulin (upper quartiles).'] Do creatinine and insulin predict cardiac mass in drug-naïve hypertensive patients?