Creatinine in the Dog: A Review

Abstract

Creatinine is the analyte most frequently measured in human and veterinary clinical chemistry laboratories as an indirect measure of glomerular filtration rate (GFR). Although creatinine metabolism and the difficulties of creatinine measurement have been reviewed in human medicine, similar reviews are lacking in veterinary medicine. The aim of this review is to summarize information and data about creatinine metabolism, measurement, and diagnostic significance in the dog. Plasma creatinine originates from the degradation of creatine and creatine phosphate, which are present mainly in muscle and in food. Creatinine is cleared by glomerular filtration with negligible renal secretion and extrarenal metabolism, and its clearance is a good estimate of GFR. Plasma and urine creatinine measurements are based on the nonspecific Jaffé reaction or specific enzymatic reactions; lack of assay accuracy precludes proper interlaboratory comparison of results. Preanalytical factors such as age and breed can have an impact on plasma creatinine (P-creatinine) concentration, while many intraindividual factors of variation have little effect. Dehydration and drugs mainly affect P-creatinine concentration in dogs by decreasing GFR. P-creatinine is increased in renal failure, whatever its cause, and correlates with a decrease in GFR according to a curvilinear relationship, such that P-creatinine is insensitive for detecting moderate decreases of GFR or for monitoring progression of GFR in dogs with severely reduced kidney function. Low sensitivity can be obviated by determining endogenous or exogenous clearance rates of creatinine. A technique for determining plasma clearance following IV bolus injection of exogenous creatinine and subsequent serial measurement of P-creatinine does not require urine collection and with additional studies may become an established technique for creatinine clearance in dogs.

Hematology and Blood Chemistry Parameters Differ in Free-Ranging Maned Wolves (Chrysocyon Brachyurus) Living in the Serra Da Canastra National Park Versus Adjacent Farmlands, Brazil

“…Male and female wolves also differed in circulating glucose and creatinine phosphokinase concentrations, which probably reflected a higher metabolism for females, a phenomenon that occurs at least in the domestic dog (Heffron et al, 1976). However, unlike the domestic dog (Braun et al, 2003), male maned wolves had higher serum potassium than female counterparts, demonstrating species variations in certain serum biochemistry traits.…”

Is Progressive Chronic Kidney Disease a Slow Acute Kidney Injury?

“…We have relied on serum creatinine for at least a century to predict the adequacy or inadequacy of kidney function with relative utility. 3 More recently SDMA has become available to complement some of the short-comings of creatinine, but additional time is required to duly establish its role and acceptance. (See Relford et.…”

“…in this edition) Despite familiarity with creatinine for the diagnosis of kidney disease, its utility has been constrained by the misperception it is blinded to early and subclinical kidney dysfunction and its excessively broad reference range for dogs and cats. 3 IRIS CKD Stage 1 encompasses the normal reference range for creatinine which creates confusion identifying this stage as CKD. Documented CKD often is associated with the bias that the disease is advanced at the time of diagnosis, and the kidney fate is predetermined.…”

Evaluation of the Measurement of Serum Cystatin C by an Enzyme-Linked Immunosorbent Assay for Humans as a Marker of the Glomerular Filtration Rate in Dogs

“…However, they usually increase after a severe reduction in GFR [5]. For example, the GFR level has to halve before the Cre concentration rises significantly.…”

“…Factors that can alter the plasma UN concentration include high protein intake, fever, intestinal hemorrhage, and catabolic state. In dogs, the plasma Cre concentration is influenced by the ratio of body weight to muscle mass [5], and small quantities of Cre are secreted by the renal tubules in male dogs [11]. Thus, plasma UN and Cre concentrations cannot detect mildly reduced renal function.…”