Lee HC, Chuang KI, Lu CF, et al. - The present study was conducted to ascertain whether contrast medium volume and method of administration and baseline estimated glomerular filtration rate affect the efficacy of prophylactic hydration for prevention of acute kidney injury after contrast administration. Researchers carried out an online search of PubMed on August 25, 2017, produced a total of 697 studies. Nine were included in this study after the reports were reviewed,. The separated extracted data on all patients in these studies into a group that received prophylactic hydration and a group that did not. They applied following three criteria for subgroup analysis: contrast medium volume, contrast administration method, and baseline estimated glomerular filtration rate. They conducted t test, and estimated study-level odds ratios with 95% CIs and p values. Tests of heterogeneity were performed. The prevalent practice for contrast-enhanced CT studies, prophylactic hydration may not be required, regardless of the estimated glomerular filtration rate or route of contrast administration for patients who receive less than 100 mL of contrast medium. Hydration is recommended to prevent contrast-induced acute kidney injury for individuals undergoing techniques requiring administration of large volumes of contrast medium.