A paper in Kidney International in December last year (brought to my attention in an email from Cathy Jordan, Medical Librarian at the Walter Reed Army Medical Center in Washington DC, to the MEDLIB-L list) examined where renal research was published. The authors looked at 2779 primary studies, identified through 195 systematic reviews. 49 percent were published in the top 20 journals on the resulting list. 10 of those journals were not renal journals. The remaining 51 percent of papers were published in 446 different journals. Therefore, almost half of renal research is published in non renal journals, and the authors say in the abstract:
"Browsing the top journals is important. However, relevant studies are also scattered across a large range of journals that may not be routinely scanned by busy physicians, and keeping up with this literature requires other continuing education strategies."
Browsing can be done in a library, if they happen to have the top journals in print, or by signing up to receive electronic tables of contents for those journals. Your "other continuing education strategies" could include setting up an alert search in Medline or another database, for material in a particular subject. Or your librarian could do this for you. The whole of renal medicine might be too big for this, but your particular interests in it might not be.
The authors of the paper include McKibbon and Haynes of McMaster University, and the abstract is here: http://www.nature.com/ki/journal/v70/n11/abs/5001896a.html. Links to full text will work if you subscribe (we do, at Leicester). The reference is:
Garg AX, Iansavichus AV, Kastner M, Walters LA, Wilczynski N, McKibbon KA, et al. Lost in publication: Half of all renal practice evidence is published in non-renal journals. Kidney Int. 2006;70(11):1995-2005.