Martin-Lorenzo M, et al. - Researchers assessed urinary proteome changes as a predictor of response to spironolactone in 29 resistant hypertensives in this prospective study. Prior to spironolactone administration, basal urine samples were collected, and blood pressure control was used as a criterion to classify patients as responders or nonresponders. Protein quantitation was done. The most significant variations were displayed by haptoglobin and haptoglobin-related protein. Of 3,310 identified proteins, nonresponders (vs responders) had increased levels of these proteins before drug administration (variation rate, 5.98 and 7.83, respectively). In functional enrichment analysis, oxidative stress, chronic inflammatory response, blood coagulation, complement activation, and regulation of focal adhesions were identified as physiopathological mechanisms in resistant hypertension when protein-coordinated responses were assessed. For the first time, protein changes were identified as a predictor of response to spironolactone in basal urine.