Purpose of review
The kidney, like most other organs, has a reserve capacity that can be utilized in times of increased physiologic demand. The ability to quantify this renal reserve function across various parts of the nephron (glomerular and tubular) has been an area of increased investigation over the past several years. In this review, we discuss several techniques that have been developed to interrogate the maximal physiologic capacity of the injured kidney.
Although protein loading has been established as an ideal method to investigate glomerular filtration capacity in healthy kidneys, other methods such as the antagonism of the renin–angiotensin–aldosterone system have demonstrated promise as a method to determine underlying glomerular disease in those with acute kidney injury
and other comorbidities (e.g., congestive heart failure and chronic kidney disease). The furosemide stress test
has been demonstrated to be a useful clinical tool to ascertain tubular integrity in the setting of acute kidney injury
Although various methods to interrogate the reserve capacity of the several nephron segments (glomerulus and tubules) have been investigated, none of these techniques have had wide-spread clinical implementation. Further research into acute kidney injury
stress testing is warranted.