Search Results

You are looking at 1 - 10 of 41 items for

  • Author or Editor: Dennis J. Chew x
  • Refine by Access: Content accessible to me x
Clear All Modify Search

Abstract

Objective—To determine concentrations of calcium (total [tCa], ionized [iCa], protein-bound [pCa], and complexed [cCa]) in dogs with chronic renal failure (CRF).

Animals—23 dogs with CRF.

Procedure—Serum calcium was fractionated by use of a micropartition system. Total calcium and iCa concentrations and pH were measured in unfractionated serum, and tCa concentration was measured in the ultrafiltrate. The pCa fraction was calculated by subtracting tCa of the ultrafiltrate from tCa concentration of unfractionated serum. The iCa concentration in unfractionated serum was subtracted from tCa concentration in the ultrafiltrate to determine the concentration of cCa.

Results—Concentrations of tCa, iCa, pCa, and cCa had wide ranges among dogs with CRF. Dogs with significantly low tCa concentration (7.70 ± 1.73 mg/dL) had cCa concentration (0.76 ± 0.38 mg/dL) within reference range, whereas dogs with reference range to high tCa concentration (10.85 ± 1.13 mg/dL) had significantly high cCa concentration (2.62 ± 1.04 mg/dL). There was no significant difference in iCa or pCa concentrations between groups.

Conclusions and Clinical Relevance—Concentrations of tCa, iCa, cCa, and pCa varied widely in dogs with CRF. Overall, cCa concentration was high, although subpopulations differed in cCa and tCa concentrations. Differences in tCa concentration were primarily attributable to differences in cCa fraction. (Am J Vet Res 2003;64:1181–1184)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether total serum calcium (tCa) or adjusted tCa concentrations accurately predict ionized calcium (iCa) status in dogs.

Sample Population—1,633 canine serum samples.

Procedure—The tCa concentration was adjusted for total protein (TP) or albumin concentration by use of published equations. Correlations between iCa and tCa or adjusted tCa, tCa and TP, and tCa and albumin were calculated. Diagnostic discordance between tCa or adjusted tCa and iCa was determined. Diagnostic discordance in predicting iCa was also determined for 490 dogs with chronic renal failure (CRF). Sensitivity, specificity, positive and negative predictive values, and positive and negative diagnostic likelihood ratios were calculated for tCa, tCa adjusted for TP, and tCa adjusted for albumin.

Results—Diagnostic discordance was 27% when tCa concentration was used to predict iCa status. Use of adjusted tCa increased diagnostic discordance to approximately 37% for all dogs and 55% for dogs with CRF. Positive predictive value and positive diagnostic likelihood ratios were poor when tCa concentration was used to predict iCa status. The tCa concentration overestimated normocalcemia and underestimated hypocalcemia. Adjusted tCa overestimated hypercalcemia and underestimated hypocalcemia.

Conclusions and Clinical Relevance—Adjusted tCa or tCa concentrations are unacceptable for predicting iCa status in dogs. Use of adjustment equations is not recommended. Direct measurement of iCa concentration is necessary for accurate assessment of calcium status. Use of tCa or adjusted tCa concentrations to predict iCa status in dogs could cause serious mistakes in diagnosis and case management, especially in dogs with CRF. (Am J Vet Res 2005;66:1330–1336)

Full access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the effect of number of blood samples and sampling times on plasma clearance of technetium Tc 99m pentetate (Tc99mP) and orthoiodohippurate sodium I 131(OIH).

Animals—20 dogs and 14 cats.

Procedure—Plasma clearances of OIH and Tc99mP were calculated by use of a 2-compartment model, on the basis of a 12-point curve as a reference method. Plasma clearance was calculated by use of all possible combinations of 4 to 11 samples. Time schedule yielding the smallest difference from the reference method was considered to be optimal. Regression analysis was performed between the 12-point model and models using a reduced number of samples.

Results—SD of the difference between the 12-point clearance and the models with reduced numbers of samples increased when the number of samples decreased. The SD of the difference between 12-point clearance and 4-point clearance was 4.17 ml/min for OIH and 0.94 ml/min for Tc99mP in dogs and 0.45 ml/min for OIH and 0.11 ml/min for Tc99mP in cats. Optimal schedules were distributed logarithmically and included an early sample at 5 or 10 minutes, a late sample at 2.5, 3, 4, or 5 hours for OIH, and a late sample at 4 or 5 hours for Tc99mP.

Conclusions and Clinical Relevance—Plasma clearances of OIH and Tc99mP can be accurately calculated in dogs and cats by use of a single-injection 2-compartment pharmacologic model with a reduced number of blood samples, resulting in an acceptable margin of error. (Am J Vet Res 2000;61:280–285)

Full access
in American Journal of Veterinary Research

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
in Journal of the American Veterinary Medical Association

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