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Abstract

Objectives

To determine usefulness of a micropartition system for calcium fractionation of canine serum, and to establish reference values for protein-bound, complexed, and ionized calcium fractions in clinically normal dogs.

Design

Performance characteristics of a micropartition system were evaluated, using serum from clinically normal dogs. This micropartition system was then used to determine a reference range for calcium fractions.

Animals

13 clinically normal dogs.

Procedure

Dog serum was placed in the micropartition system, and spun for 20 minutes at 1,300 × g. Total calcium concentration, ionized calcium concentration, and pH were measured in whole serum, and total calcium concentration was measured in the ultrafiltrate. The protein-bound fraction was calculated by subtracting total calcium of the ultrafiltrate from total calcium of whole serum. The ionized calcium measurement of whole serum was subtracted from the total calcium measurement of the ultrafiltrate, determining the complexed calcium fraction.

Results

During validation of the ability of the micropartition system to separate calcium fractions, no significant amount of serum calcium was adsorbed by the plastic micropartition system or membrane. The micropartition membrane separated the protein-bound calcium fraction (retentate) from the ultrafiltrate, which contained ionized and complexed fractions of calcium. Concentrations of protein-bound, ionized, and complexed calcium from clinically normal dogs were determined to be 3.40 ± 0.63, 5.49 ± 0.17, and 1.01 ± 0.30 mg/dl, representing 34, 56, and 10% of the total calcium concentration, respectively.

Conclusions

This method is a rapid, repeatable means to completely fractionate serum calcium, and most importantly provides accurate assessment of the protein-bound and complexed calcium fractions.

Clinical Relevance

Complete assessment of calcium fractions may increase sensitivity for detection of disease processes that affect calcium metabolism.(Am J Vet Res 1996;57:268-271 )

Free access
in American Journal of Veterinary Research

SUMMARY

The stability of ionized calcium (CaI) concentration and pH in sera (n = 14) stored at 23 or 4 C for 6, 9, 12, 24, 48, or 72 hours, or −10 C for 1, 3, 7, 14, or 30 days was evaluated. Also studied were the effects of oxygen exposure, cold handling, and feeding on CaI and pH values. Results indicated that serum CaI concentration was stable throughout 72 hours of storage at 23 or 4 C, and for 7 days at −10 C. Serum CaI concentration significantly (P < 0.05) decreased by 14 days of storage at −10 C. Serum pH was stable for 6 hours at 23 or 4 C, and for 24 hours at −10 C, but significantly (P < 0.05) increased by 9 hours of storage at 23 or 4 C and by 3 days at −10 C. Exposure of the surface of the serum to air immediately before measurement had no effect on CaI or pH values, but mixing serum with air resulted in significantly (P < 0.05) decreased CaI concentration and increased pH. Handling of blood on ice resulted in significantly (P < 0.05) higher serum pH, compared with blood handled at 23 C, but serum CaI concentration was unaffected. Serum obtained at 2 hours after feeding did not have any significant changes in CaI total calcium, or pH values. It appears that if canine serum is obtained, handled, and stored anaerobically, CaI concentration can be accurately measured after 72 hours at 23 or 4 C, or after 7 days at −10 C.

Free access
in American Journal of Veterinary Research

SUMMARY

Acute nephrotoxicosis was induced in ewes by daily sc administration of gentamicin. Activity of 3 urine enzymes, γ-glutamyltransferase (ggt), β-N-acetylglucosaminidase (ags), and β-glucuronidase (grs), were measured during the development of aminoglycoside nephrotoxicosis. Measurements from timed, volume-measured urine samples were performed on days 0, 7, and 8. Measurements from urine samples obtained without volume measurement (spot samples) were performed daily. Urine ggt and ags activities were high 3 days prior to detection of high serum creatinine concentration and 1.5 days before the appearance of casts in the urine sediment; values consistently remained in the abnormal range until termination of the study. High urine grs activity was inconsistent and transient; serum ggt activity did not change during the course of the study. Urine ggt and ags activities expressed as total excretion per unit time and body weight, enzyme activity per unit volume, and as ratio of urine enzyme activity to urine creatinine concentration were strongly correlated. Urine ggt and ags, but not grs activities, are suitable indicators of renal tubular cell damage in sheep with aminoglycoside nephrotoxicosis. Urine ggt and ags activities indicate cellular changes occurring several days prior to the first indications of renal functional change.

Free access
in American Journal of Veterinary Research

SUMMARY

Aminoglycoside nephrotoxicosis (agnt) was induced in ewes by daily sc administration of gentamicin. Changes in urinary indices of renal function during the development of agnt are reported. Measurements from timed, volume-measured urine samples were made on days 0, 7, and 8 and included creatinine clearance, total excretion (te) rates of electrolytes (Na, K, Cl, P) and urine volume. Measurements from free-catch urine samples (without volume measurement) were made daily and included fractional excretion (fe) rate of electrolytes, urine osmolality, and urine-to-serum osmolality and urine-to-serum creatinine ratios. With the onset of agnt, FE rates of Na, K, Cl, and P increased many fold above baseline values (200 ×, 4 to 5 ×, 6 to 9 ×, and 70 to 95 ×, respectively, on days 7 and 8), indicating decreased tubular reabsorption or increased tubular secretion. The increased FE rates were not representative of increases in total electrolyte excretion rates. The total excretion of Na (TENa) was mildly increased, TEK was decreased, TECl was unchanged, and TEP was significantly increased on days 7 and 8. Abnormal urinalysis results, glucosuria, and increased FEP preceded appreciable increase in serum creatinine concentration. Other abnormal urinary indices of renal function coincided with or followed the increase in serum creatinine concentration. Urinary indices may help characterize renal function associated with the disease state, but did not provide early indication of agnt.

Free access
in American Journal of Veterinary Research

SUMMARY

Urinary indices of renal function and damage were measured in 6 healthy, mature ewes over a 48-hour period. Endogenous creatinine clearance, total and fractional electrolyte excretion rates, protein excretion, urine volume, and urine γ-glutamyltransferase and β-glucuronidase activities were measured. Significant variations in the excretion rates of creatinine, electrolytes, and protein were not found between intervals within the 48-hour urine collection period. Total urinary electrolyte excretion rates were significantly (P < 0.001) correlated with fractional electrolyte excretion rates normalized for creatinine concentration; however, coefficient of determination was low.

Free access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To evaluate effects of blood contamination on dipstick results, specific gravity (SG), and urine protein-to-urine creatinine ratio (UPCR) for urine samples from dogs and cats.

SAMPLE Urine samples collected from 279 dogs and 120 cats.

PROCEDURES Urine pools were made for each species (dogs [n = 60] and cats [30]). Blood was added to an aliquot of a pool, and serial dilutions were prepared with the remaining urine. Color and dipstick variables were recorded, and SG and UPCR were measured. For cats, 1 set of pools was used; for dogs, 2 sets were used. Comparisons were made between undiluted urine and spiked urine samples for individual colors. Repeated-measures ANOVA on ranks was used to compare dipstick scores and UPCR results; χ2 tests were used to compare proteinuria categorizations (nonproteinuric, borderline, or proteinuric).

RESULTS Any blood in the urine resulted in significantly increased dipstick scores for blood. In both species, scores for bilirubin and ketones, pH, and SG were affected by visible blood contamination. No significant difference for the dipstick protein reagent results was evident until a sample was visibly hematuric. The UPCR was significantly increased in dark yellow samples of both species. Proteinuria categorizations differed significantly between undiluted urine and urine of all colors, except light yellow.

CONCLUSIONS AND CLINICAL RELEVANCE Any degree of blood contamination affected results of dipstick analysis. Effects depended on urine color and the variable measured. Microscopic blood contamination may affect the UPCR; thus, blood contamination may be a differential diagnosis for proteinuria in yellow urine samples.

Full access
in American Journal of Veterinary Research