Urine sample collection

1 Plasma Creatinine, Urea (Blood Urea Nitrogen), and Cystatin C 

These plasma tests are used as indirect measurements of the glomerular filtration rate (GFR) to some extent, these endogenous tests supplement each other despite having different limitations. Plasma creatinine, urea, and cystatin C are normally filtered from the plasma, and they are reabsorbed or secreted by the proximal tubules to a minor extent, which differs between species. Tubular secretion leads to overestimation of GFR and it is higher in laboratory animals than in man. These secretions/reabsorption mechanisms may change as a consequence of major tubular injury. In addition to renal injury, the GFR may be altered by changes of renal hemodynamics or extracellular dehydration. 

Creatinine is a product of the degradation of creatine and creatine phosphate, which are present mainly in muscle and in food. Plasma creatinine is dependent on muscle mass and can be lowered in severe myopathy. Although plasma levels are less affected by diet compared to urea, malnutrition may lower plasma creatinine (Evans 1987 Braun, Lefebvre, and Watson 2003). Plasma creatinine is normally filtered from the plasma, and it is reabsorbed and secreted by the proximal tubules to a minor extent, although secretion is higher in rodents compared to humans. Elevated plasma creatinine is a reliable indicator of impaired glomerular filtration or alterations in renal blood flow, but severe tubular dysfunction can also increase plasma creatinine. 

Plasma and urinary creatinine are commonly measured by the colorimetric alkaline picrate method of Jaffe or by alternative enzymatic methods. Enzymatic methods use creatinine amidohydrolase or creatinine iminohydrolase and are more specific for creatinine. The measurement of plasma creatinine may be affected by endogenous noncreatinine chromogens (e.g., bilirubin and ketones) this can overestimate plasma creatinine in dogs by up to 45% and to an even greater extent in rats 

In addition to using plasma creatinine (or cystatin C) as an indicator of GFR, several other methods for estimating GFR can be expressed as 

---

All inpatients admitted through the hospital emergency room over a 15-month period (June 1982 through August 1983) had urine samples collected in the emergency room for later PCP assay. This represented 1,550 admissions of 1,384 individual patients, but did not include all hospital inpatients (1.e., excluded those who were admitted from outpatient status). PCP was detected in the urine of 16.5 percent (255) of the total admissions and 15.5 percent (215) of individual patients. In the vast majority of cases, the PCP levels were low (less than 30 ng/ml in 85.0 percent). 

Under field exposure conditions, it is recommended to measure PA herbicides in 24-hr urine samples collected starting at the end of the work-shift. Spot samples collected at the end of exposure or the following morning can be used when a 24-hr urine collection is impractical. In this case, the concentration of the compounds should be normalized to creatinine concentration or adjusted for specific gravity. 

In contrast to the other large cats, the urine of the cheetah, A. jubatus, is practically odorless to the human nose. An analysis of the organic material from cheetah urine showed that diglycerides, triglycerides, and free sterols are possibly present in the urine and that it contains some of the C2-C8 fatty acids [95], while aldehydes and ketones that are prominent in tiger and leopard urine [96] are absent from cheetah urine. A recent study [97] of the chemical composition of the urine of cheetah in their natural habitat and in captivity has shown that volatile hydrocarbons, aldehydes, saturated and unsaturated cyclic and acyclic ketones, carboxylic acids and short-chain ethers are compound classes represented in minute quantities by more than one member in the urine of this animal. Traces of 2-acetylfuran, acetaldehyde diethyl acetal, ethyl acetate, dimethyl sulfone, formanilide, and larger quantities of urea and elemental sulfur were also present in the urine of this animal. Sulfur was found in all the urine samples collected from male cheetah in captivity in South Africa and from wild cheetah in Namibia. Only one organosulfur compound, dimethyl disulfide, is present in the urine at such a low concentration that it is not detectable by humans [97]. 

Following intramuscular administration to sheep of 1 mg xylazine/kg bw, two-thirds of the injected dose could be absorbed within 10 min (113). The drug was rapidly distributed to different tissues, and rapidly eliminated. The rapid elimination of xylazine in sheep is probably related to its intense metabolism rather than to its rapid renal excretion. This hypothesis was supported by the lack of significant amounts of the intact drug in urine samples collected every 10 min from treated sheep. 

In the period 1992-1993, extensive surveillance for the potential presence of -agonists in veal calves, young catde, and cows was carried out (11). A total of 7121 and 5883 urine samples collected at the slaughter phase in 1992 and 1993, respectively, were tested. Analysis results revealed 264 positive samples (3.7%) in 1992 and 397 positive samples (6.7%) in 1993. 

The clearance of radioactive silver metal dust in a man who was accidentally exposed illustrated the rapid removal of silver from the lungs primarily by ciliary action, with subsequent ingestion and ultimate elimination in the feces (Newton and Holmes 1966). Lung clearance fit a biexponential profile, with biological half-lives of 1 and 52 days. Radioactive silver was detected in the feces up to 300 days after exposure, but was not detected in urine samples (collected up to 54 days after exposure). 

D levels were measured in urine samples collected prior to, during, and after actual spray operations from workers involved in ground and aerial applications of amine and ester formulations of... 

EPA Study. The first published report of studies on 2,it,5-T applicators was by Shafik et al. of EPA in 1971 (] ) They analyzed urine samples collected from people occupationally exposed to 2,lt-D and 2,it,5-T, and reported higher exposure in spray operators than in those who had less direct contact with the herbicides. 

Kissel, J.C., C.L. Curl, G. Kedan, C. Lu, W. Griffith, D.B. Barr, L.L. Needham, and R.A. Fenske. 2005. Comparison of organophosphorous pesticide metabolite levels in single and multiple daily urine samples collected from preschool children in Washington State. J. Expo. Anal. Environ. Epidemiol. 15(2) 164-171. 

The feasibility of using the monoester metabolites as specific biomarkers of exposure to DEHP and six other commonly used phthalates was shown in a study of urine samples collected from 289 adults during 1988-1994 as part of the Third National Health and Nutrition Examination Survey (NHANES III)... 

Urine samples collected from two human subjects, prior to (minus 24 to 0 hours) and after (plus 2 to 6 hours) oral administration of 30 mg A9-THC, were hydrolyzed and extracted as described in the experimental section. Pre- and post-drug extracts corresponding to equivalent urinary creatinine levels were separated by reverse phase HPLC. The pre-drug extract was used as a... 

Either 24 hour urine collection or timed urine samples collected at the same time each day is recommended, with the activity expressed per unit of time (Price 1982, Plummer et al. 1986). If the assessment is to be repeated with time, the samples should be collected over the same time period on each day because there is pronounced diurnal variation in excretion rate of some enzymes (Maruhn et al. 1977, Price 1982, Gossett et al. 1987). For spot urine samples or those where accurate timed collection is not possible, normalization of activity per unit of creatinine can be done and this has been shown to be reasonably well correlated to 24 hour enzyme activity (Vanderlinde 1981, Grauer et al. 1995). Diet and age-matched controls must be included if enzyme activity is to be normalized to creatinine, to control for the effects of these variables on creatinine excretion (Plummer et al. 1986, Casadevall et al. 1995). 

Einbrodt et al. (1976) exposed students to 0.26-0.92 ppm formaldehyde vapors for 3 hours, with urine samples collected immediately after exposure and 21 hours after exposure. Urine formaldehyde and urine formic acid (formate) concentrations were found to be higher immediately after exposure compared to 21 hours later however, no baseline sample was obtained prior to exposure. If historic formaldehyde and formic acid baseline levels were assumed, then a closer examination of these data indicates that more formaldehyde (and metabolite) was excreted in the urine than could have possibly been absorbed by inhalation, indicating another route of exposure (perhaps dermal), or co-exposure to another chemical that also has formate as a metabolite (e.g., methanol), or higher personal exposures than were actually measured. There was also no indication that the urine formate levels were adjusted to compensate for urine specific gravity using urine creatinine levels, which may have markedly influenced the test results. 

Elimination and excretion of 2-butoxyethanol after inhalation exposure appears to be similar in both humans and animals. Human studies suggest that excretion of 2-butoxyacetic acid is variable. Volunteers were exposed to 98 or 195 ppm 2-butoxyethanol for 8 hours (Carpenter et al. 1956). Urinalyses for free 2-butoxyacetic acid were conducted on urine samples collected during the 24 hours following the end of the exposure period. Results showed that at the 195-ppm exposure level, one male excreted 175 mg and one female excreted 300 mg of 2-butoxyacetic acid in the 24-hour period. Another male exposed to 195 ppm excreted only trace amounts of 2-butoxyacetic acid. Subjects exposed to 98 ppm (n=4) showed the following values for excreted 2-butoxyacetic acid 100 mg (one female),... 

Figure 7.8 HPLC-APCI-MS SIM chromatographic profiles of an extract of a urine sample collected from a healthy male subject. From E. C. Y. Chan and P. C. Ho, Rapid Communications in Mass Spectrometry, 14, 1959-1964. Copyright 2000 John Wiley Sons, Ltd. Reproduced with per-...

---