Creatinine Ratio In Urine Samples Research Articles

Effect of common storage temperatures and container types on urine protein : creatinine ratios in urine samples of proteinuric dogs.

BackgroundPreanalytic protein adsorption to polymer and glass container surfaces may decrease urine protein concentration measurements and urine protein: creatinine ratios (UPC).Hypothesis/ObjectivesUrine stored in PC or glass containers will have lower UPC than urine stored in HP containers. The specific objective was to determine whether clinically relevant differences in UPC would be detected after storage in glass, PC, or HP containers using common storage times and temperatures.AnimalsTwelve client‐owned dogs with proteinuria.MethodsProspective, nonmasked study, divided into 2 phases. The first phase was a pilot study involving multiple (n = 5) measurements at each storage condition using 24‐hours urine samples from 2 dogs with persistent renal proteinuria of different magnitude. The second phase used urine samples from 10 dogs with proteinuria of variable magnitude. Sample aliquots were stored in HP, PC, and glass containers at 24°C for 4 hours, 4°C for 12 hours, and −20°C for 72 hours. The UPC of each was measured after storage and compared with baseline.ResultsStatistically significant but clinically irrelevant differences were found in phase 1. In phase 2, storage conditions did not affect urinary protein or creatinine concentrations or UPC.Conclusions and Clinical ImportanceCollection and storage of canine urine samples in clean HP, PC, or glass containers at 24°C for 4 hours, 4°C for 12 hours, or −20°C for 72 hours is unlikely to result in clinically relevant decreases in measured UPC values.

Protein: creatinine and trypsin inhibitor: creatinine ratios in the urine of marathon runners

We measured changes in the protein: creatinine and trypsin inhibitor: creatinine ratios in the urine of six male marathon runners. Samples of urine were collected before the run, immediately after the run and in 6-h collections for 2 days. We found the greatest increase in the protein: creatinine ratio (2.6 times greater) in urine collected immediately after the run and the greatest increase in the trypsin inhibitor: creatinine ratio in urine samples collected 6-12 and 12-18 h after the run (2 and 3 times greater, respectively). This suggests the existence of different mechanisms for these two physiological processes. The later increase in the trypsin inhibitor: creatinine ratio was perhaps, due to a state of short-lived inflamation and shock after severe physical effort.

Creatinine as an index substance for estimating the urinary excretion of nitrogen and potassium by grazing sheep

The use of creatinine as an index of urinary nitrogen and potassium excretion of grazing sheep was examined in three experiments. Separate relationships between creatinine excretion and liveweight were derived for ewes and wethers in experiment 1. These equations were used in experiment 2 to predict the urinary nitrogen and potassium excretion of sheep maintained in metabolism cages from the nitrogen : creatinine and potassium : creatinine ratios in urine samples taken at 0900 and 1630 hours. These estimates were compared with the measured urinary nitrogen and potassium output. It was concluded that urinary nitrogen excretion of one sheep on one day could be estimated with a random error of ± 17% and potassium output with an error of ± 24%. Both estimates were subject to bias. In experiment 3, changes in the nitrogen : creatinine and potassium : creatinine ratios of six grazing wethers were measured; a diurnal trend in the nitrogen : creatinine ratio was observed. The reliability of two possible sampling procedures was examined and it was concluded that under grazing conditions the technique could only be used to detect large differences in urinary nitrogen and potassium excretion.