Back to Basics: Is There a Good Reason to Not Systematically Measure Urine Creatinine in Acute Kidney Injury Monitoring?

Abstract

Regardless of the recent advancements in the understanding of the pathophysiology of acute kidney injury (AKI), its diagnosis remains fundamentally dependent on the serum creatinine (sCr) level and urine output (UO), both of which are considered late markers of AKI, offering only a vague idea of the actual creatinine clearance (CrCl). Although not ideal, CrCl is still the most common alternative of the glomerular filtration rate (GFR) in clinical practice. It is generally accepted that early diagnosis of AKI must reveal kidney impairment before sCr increases. Much effort has been made to find tubular and glomerular markers of injury which increase (in blood and/or in urine) before the ‘official' diagnosis of AKI. Most of these markers are expensive and not widely available, especially in developing countries. Urine creatinine (CrU), the major link between sCr and UO, has been systematically ignored and clinicians are usually unaware of its value. The reasons for this are unclear, but it may be related to the lack of a reference range, dependence of its concentration value on the urine flow (which in turn is only adequately assessed with an indwelling urinary catheter) and the clinical unavailability of its counterbalance part - creatinine production. Changes in urine tend to precede changes in blood in the course of AKI development and recovery. Hence, it is important to bear in mind that changes in sCr signal renal dysfunction with a significant delay. The search for a more dynamic, ‘real-time' but pragmatic assessment of renal function, especially in patients at risk of abrupt decrease in GFR is certainly one of the most relevant focus of research in the field of AKI monitoring. Systematic CrU assessment may be highly relevant in this case.

Comparison of Urine Creatinine Levels between Agricultural Workers and Non-Agricultural Workers in Wuluhan District Jember Regency

“…The human kidney is one of the organs that plays an important role in maintaining water and electrolyte balance and plays a role in regulating the body's metabolism.The presence of disturbances in kidney function can be known through laboratory examinations, one of which is by measuring the body's metabolic waste materials such as creatinine (Verdiansah, 2016).Urine creatinine examination can be used to monitor the progression of kidney disease (Maciel, 2016).The results of this study indicate that urine creatinine levels in agricultural worker subjects have an average of 107.0367 mg/dL.In addition, it was also found that urine creatinine levels in non-agricultural subjects had an average of 122.4267 mg/dL.Based on the minimum maximum level, the value of urine creatinine levels in both agricultural workers and non-agricultural workers is still within normal limits, which is in the range of 20-320 mg/dL in adult men (Van Leeuwen et al, 2017).Urinary creatinine levels that are still within normal limits indicate that the kidneys still have good working functions and are able to effectively filter body waste products from the blood.…”

“…Data were obtained from structured interviews using a questionnaire for pesticide exposure data. Data on urine creatinine levels were obtained by collecting random urine specimens of the middle portion which were then examined by the Jaffe-reaction method (Maciel, 2016).…”

Urine biochemistry assessment in the sequential evaluation of renal function: Time to think outside the box

“…A reliable method for early identification of impairment of creatinine excretion is to quantify the mass of creatinine excreted over a certain time period (6 h, for example). The mass of excreted creatinine is the result of the balance between UO and urine creatinine concentration (CrU), a parameter routinely not assessed in clinical practice ( 26 ).…”

Reference Intervals of Spot Urine Creatinine-to-Osmolality Ratio as a Surrogate of Urinary Creatinine Excretion Rate

“…Nowadays, widely accepted estimated GFR (eGFR) formulas, such as MDRD equation [ 1 ], MDRD-EPI Creatinine equation [ 2 ], and MDRD-EPI Creatinine-Cystatin equation [ 3 ], are all developed for conditions with assumptively steady SCr levels. However, for a situation with ever-changing SCr levels as in acute kidney injury (AKI), few suitable manners for the evaluation of instant renal excretion function have been proposed [ 4 , 5 ].…”