Pre-renal success

Abstract

To the Editor: Holtkamp et al.1.Holtkamp R.A. de Zeeuw D. Thomas M.C. et al.An acute fall in estimated glomerular filtration rate during treatment with losartan predicts a slower decrease in long-term renal function.Kidney Int. 2011; 80: 282-287Abstract Full Text Full Text PDF PubMed Scopus (248) Google Scholar demonstrated that initial declines in glomerular filtration rate (GFR) resulting from renin–angiotensin system inhibition (RASI) are commonly associated with improved long-term renal function. The underlying physiologic principles have been well described and the initial studies upon which this review was based are over 10 years old,2.Apperloo A. De Zeeuw D. De Jong P. A short-term antihypertensive treatment-induced fall in glomerular filtration rate predicts long-term stability of renal function.Kidney Int. 1997; 51: 793-797Abstract Full Text PDF PubMed Scopus (185) Google Scholar, 3.Maschio G. Alberti D. Janin G. et al.Effect of the angiotensin-converting enzyme inhibitor benazepril on the progression of chronic renal insufficiency. The Angiotensin-Converting Enyzme Inhibition in Progressive Renal Insufficiency Study Group.N Engl J Med. 1996; 334: 939-945Crossref PubMed Scopus (1697) Google Scholar, 4.Bakris G. Weir M. Angiotensin-converting enzyme inhibitor-associated elevations in serum creatinine.Arch Intern Med. 2000; 160: 685-693Crossref PubMed Google Scholar but the concept remains poorly understood by the medical community. Too often, internists (and even nephrologists) diagnose the initial decline in GFR following RASI as ‘pre-renal failure’ and reverse beneficial therapy. This problem is widespread and not limited to RASI prescription; the same issue manifests when blood pressure in chronic kidney disease is lowered by non-RASI medicines.2.Apperloo A. De Zeeuw D. De Jong P. A short-term antihypertensive treatment-induced fall in glomerular filtration rate predicts long-term stability of renal function.Kidney Int. 1997; 51: 793-797Abstract Full Text PDF PubMed Scopus (185) Google Scholar Although this discordance between clinical research and clinical activity is not unique, the issue with RASIs (and blood pressure control in general) and an initial increase in serum creatinine has two specific characteristics:(1)There is no well-known succinct name for this syndrome.(2)It is not part of the commonly taught tripartite approach to acute renal failure (‘pre-renal, renal, post-renal’). It is hard to expect a physician to diagnose something that does not have a name (only a long-winded description) or a place in the standard diagnostic algorithm. For these reasons, the term ‘pre-renal success’5.Hirsch S. Prerenal success in chronic kidney disease.Am J Med. 2007; 120: 754-759Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar has been suggested for the situation described by Holtkamp et al. and others. Pre-renal success was selected for its contradistinction to the opposing (and usual) diagnosis of ‘pre-renal failure’; ‘pre-renal’ notes that the increased serum creatinine results from hemodynamic factors, and ‘success’ accentuates the key point that the long-term result is something good; the therapy should be maintained, not reversed. ‘Pre-renal success’ is a variant of the term ‘acute renal success’ used by Thurau and Boylan6.Thurau K. Boylan J. Acute renal success. The unexpected logic of oliguria in acute renal failure.Am J Med. 1976; 61: 308-315Abstract Full Text PDF PubMed Scopus (206) Google Scholar for the role of oliguria in acute tubular necrosis. I suggest that ‘pre-renal success’ be added to the standard teaching approach to elevations in the serum creatinine (Figure 1). When it appears that the reason for an increased serum creatinine is hemodynamic (pre-renal), physicians should evaluate the clinical characteristics that distinguish pre-renal failure from pre-renal success.5.Hirsch S. Prerenal success in chronic kidney disease.Am J Med. 2007; 120: 754-759Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar A proper name for this syndrome, and place in the standard algorithm, should ease the current diagnostic difficulties.