Toward the optimal clinical use of the fraction excretion of solutes in oliguric azotemia.
While the fractional excretion of solutes have long been considered excellent research tools to investigate tubular physiology, their clinical use has become common over the last 40 years in the diagnoses of many disorders; however, none have reached the clinical utility of the fractional excretion of sodium in the ability to distinguish pre-renal azotemia from acute tubular necrosis. Nevertheless, there are many drugs and medical conditions that interfere with that utility and recently other solutes, including urea, uric acid and lithium, have been recently investigated to improve the diagnostic ability in clinical situations where the fractional excretion of sodium is known to be unreliable. We review the tubular physiology of these solutes and show how the differences in tubular physiology might be exploited to develop a strategy for their optimal clinical use.
Hypertension, Nephrology, Dialysis, and Transplantation Clinic, Auburn University, Opelika, AL 36801, USA. hndt512@bellsouth.net
Charles J
CJ
Diskin
Thomas J
TJ
Stokes
Linda M
LM
Dansby
Lautrec
L
Radcliff
Thomas B
TB
Carter
D000042:Absorption; D058186:Acute Kidney Injury / Q000175:diagnosis*; D053099:Azotemia / Q000175:diagnosis* / Q000503:physiopathology / Q000652:urine; D001693:Biological Transport, Active / Q000502:physiology; D003937:Diagnosis, Differential; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D007679:Kidney Medulla / Q000503:physiopathology; D007684:Kidney Tubules / Q000378:metabolism / Q000503:physiopathology; D008094:Lithium / Q000378:metabolism; D009399:Nephrons / Q000378:metabolism; D009846:Oliguria / Q000175:diagnosis* / Q000503:physiopathology / Q000652:urine; D012965:Sodium Chloride / Q000378:metabolism; D014508:Urea / Q000652:urine; D014527:Uric Acid / Q000378:metabolism; D014868:Water Deprivation / Q000502:physiology*
D014527:Uric Acid; D012965:Sodium Chloride; D014508:Urea; D008094:Lithium