Hemolysis as a Factor in Clinical Chemistry and Hematology of the Dog

Measuring haemolysis in cattle serum by direct UV-VIS and RGB digital image-based methods

A simple, rapid procedure is required for the routine detection and quantification of haemolysis, one of the main sources of unreliable results in serum analysis. In this study, we compared two different approaches for the rapid determination of haemolysis in cattle serum. The first consisted of estimating haemolysis via a simple direct ultraviolet–visible (UV–VIS) spectrophotometric measurement of serum samples. The second involved analysis of red, green, blue (RGB) colour data extracted from digital images of serum samples and relating the haemoglobin (Hb) content by means of both univariate (R, G, B and intensity separately) and multivariate calibrations (R, G, B and intensity jointly) using partial least squares regression and artificial neural networks. The direct UV–VIS analysis and RGB-multivariate analysis using neural network methods were both appropriate for evaluating haemolysis in serum cattle samples. The procedures displayed good accuracy (mean recoveries of 100.7 and 102.1%, respectively), adequate precision (with coefficients of variation from 0.21 to 2.68%), limit of detection (0.14 and 0.21 g L^–1, respectively), and linearity of up to 10 g L^–1.

Effect of microaggregate filter passage on feline whole blood stored for 35 days

OBJECTIVES

The aim of this study was to compare the characteristics of fresh and stored feline red blood cells (RBCs) after passage through an 18 μm microaggregate filter.

METHODS

Nine cats were recruited for a single blood donation using an open collection system. A simulated transfusion using a syringe driver and microaggregate filter was performed over 2 h with half the blood on the day of donation and the other half after 35 days of storage. Differences in haematological parameters, haemolysis percentage and osmotic fragility (OF) were compared on the day of donation pre-filter passage (D0-) vs day of donation post-filter (D0+) or day 35 storage pre-filter (D35-) and post-filter (D35+). Blood was cultured at D0+ and D35+.

RESULTS

There were no statistically significant differences in the D0- vs D0+ comparisons. There were statistically significant (P <0.05) increases in haemolysis percentage, red cell distribution width (RDW) percentage and mean OF, and decreases in packed cell volume (PCV), RBC count, haemoglobin and haematocrit for D0- vs D35-. The same was found for D0- vs D35+ with the addition of a significant increase in mean cell haemoglobin (MCH). For D35- vs D35+ only MCH significantly increased. At day 35, 6/9 units had haemolysis percentages that exceeded 1%. This increased to 8/9 of stored units post-filter passage. All blood units cultured negative.

CONCLUSIONS AND RELEVANCE

Fresh RBCs exhibited no in vitro evidence of injury following passage through an 18 μm microaggregate filter. Increased MCH was observed in the stored blood and may represent haemolysis induced by the filter. All other changes can be explained by storage lesion rather than filter passage. The findings highlight the importance of blood banking quality controls and the need for further research to assess the effects of transfusion technique, specifically filter passage, on storage lesion-affected feline blood.

Preanalytical variables affecting the measurement of serum paraoxonase-1 activity in horses

Paraoxonase-1 (PON-1) activity is a new inflammatory and oxidative marker. Technical effects and biological factors could affect the accuracy of PON-1 activity measurement. We investigated the effects of storage at different temperatures, repeated freeze-thaw cycles, interferences from hemolytic, lipemic, and icteric samples, and seasonal effects on PON-1 activity in horses. We evaluated 2 substrates with an automated spectrophotometer. Ten equine serum samples were stored under different conditions. Although storage at room (21°C) or refrigeration (4°C) temperature induced a statistically significant decrease (p < 0.05) in PON-1 activity, this is not diagnostically relevant. PON-1 activity in frozen samples (-20°C) was stable for short-term storage; diagnostically significant (p < 0.01) fluctuations were observed after 1 mo. Four repeated freeze-thaw cycles were assessed, and all cycles affected PON-1 activity (p < 0.01); however, this was diagnostically significant only after the 4th cycle. Hemolysis induced an overestimation of PON-1 activity; lipemia and hyperbilirubinemia did not change PON-1 activity. Thirty-four horses were sampled monthly for 1 y, and PON-1 activity was higher in autumn (p < 0.05) and winter (p < 0.05) than in spring and summer.

Hemólise interfere na mensuração dos biomarcadores plasmáticos de estresse oxidativo em cães

RESUMO Considerando que, entre todas as fontes de erro analítico, a hemólise é a mais importante na rotina laboratorial, o presente estudo teve como objetivo investigar o efeito da hemólise in vitro sobre os principais biomarcadores plasmáticos de estresse oxidativo mensurados (BPEO) de cães. Para tal, amostras de sangue total de 19 cães clinicamente saudáveis foram hemolisadas em diferentes graus por ação mecânica. Amostras controle contendo baixa concentração de hemoglobina (Hb) no plasma foram comparadas com quatro graus de hemólise (<0,36; 0,36-0,60; 0,61-1,0; 1,1-4g/L Hb). Imediatamente após a hemólise, foram mensuradas as concentrações plasmáticas de ácido úrico (AU), albumina, bilirrubina, gamaglutamiltransferase (GGT), capacidade antioxidante total (TAC) e concentração de oxidante total (TOC). Os erros relativos causados pelos diferentes graus de hemólises foram calculados e confrontados com o erro total aceitável (ETA) e com o limite de erro permitido (LEP) empregados nos programas de controle de qualidade de exames laboratoriais. Foi observado que mesmo pequeno grau de hemólise gera algum erro analítico não aceitável (ETA e/ou LEP) nos BPEO mensurados, exceto na bilirrubina. Foi possível concluir que a hemólise é um fator limitante para avaliação do estresse oxidativo sistêmico mensurado no plasma, podendo causar erros que potencialmente comprometem o diagnóstico clínico.

Effect of Hemolysis on Nonesterified Fatty Acid and β-Hydroxybutyrate Concentrations in Bovine Blood

Nonesterified fatty acid (NEFA) and b-hydroxybutyrate (BHB) assays are used for evaluating dairy herds for negative energy balance and subclinical ketosis, respectively. Hemolysis is a common artifact in samples submitted to diagnostic laboratories. The effect of hemolysis on NEFA and BHB in bovine serum was determined. Hemolysis was introduced into 26 serum samples by adding serial dilutions of a red cell hemolysate, prepared by repeated freeze-thawing of EDTA-anticoagulated bovine blood. NEFA, BHB, and degree of hemolysis (hemolytic index) were measured by an automated chemistry analyzer. Two endpoint assays that differed by inclusion of a sample blank were used for NEFA measurement. A kinetic enzymatic assay with 2 reagent sources was used for BHB measurement. The assessed methods yielded similar NEFA or BHB results in baseline, nonhemolyzed samples (median NEFA: 0.25 mEq/L, median BHB: 3 mg/dL, median hemolytic index: 8 units). NEFA results were adversely affected by hemolysis, with values increasing significantly with higher degrees of hemolysis. Median values increased above a critical medical decision limit (0.40 mEq/L) at a hemolytic index of 506 units (marked hemolysis). This increase was prevented by inclusion of a sample blank. Result interpretation was affected in individual animals when samples were moderately hemolyzed (median hemolytic index: 258 units). In contrast, BHB results were unaffected by hemolysis with either reagent source. Thus, assays for measuring NEFAs should include a sample blank and NEFA results should not be interpreted in moderately to markedly hemolyzed bovine samples, because result accuracy cannot be assured.

The preanalytic phase in veterinary clinical pathology

This article presents the general causes of preanalytic variability with a few examples showing specialists and practitioners that special and improved care should be given to this too often neglected phase. The preanalytic phase of clinical pathology includes all the steps from specimen collection to analysis. It is the phase where most laboratory errors occur in human, and probably also in veterinary clinical pathology. Numerous causes may affect the validity of the results, including technical factors, such as the choice of anticoagulant, the blood vessel sampled, and the duration and conditions of specimen handling. While the latter factors can be defined, influence of biologic and physiologic factors such as feeding and fasting, stress, and biologic and endocrine rhythms can often not be controlled. Nevertheless, as many factors as possible should at least be documented. The importance of the preanalytic phase is often not given the necessary attention, although the validity of the results and consequent clinical decision making and medical management of animal patients would likely be improved if the quality of specimens submitted to the laboratory was optimized.

Hereditary phosphofructokinase deficiency in wachtelhunds

Hereditary phosphofructokinase (PFK) deficiency was diagnosed in two Wachtelhund dogs and suspected in three related Wachtelhund dogs with exercise intolerance, hemolytic anemia, and pigmenturia. Severe, persistent reticulocytosis in light of only mild anemia together with hemoglobinuria after strenuous exercise suggested PFK deficiency. Low erythrocyte PFK activity together with low 2,3-diphosphoglycerate concentrations and a high hemoglobin-oxygen affinity confirmed the diagnosis. The PFK deficiency is due to a single missense mutation in the muscle-type PFK M-PFK gene in English springer and American cocker spaniels, whippets, and mixed-breed dogs; however, these PFK-deficient Wachtelhunds do not have the same PFK mutation.

The effects of haemolysis on serum chemistry measurements in poultry

The effects of haemolysis on serum chemistry values in broiler and layer chickens, and in turkeys were determined using two types of serum chemistry analysers, a wet reagent analyser and a dry slide reagent analyser. The interfering effects of haemolysis were evaluated using eight levels of haemoglobin in serum analysed by the wet reagent instrument and six levels of haemoglobin in serum analysed by the dry slide reagent instrument. Nine serum chemistry analytical tests were performed on each analyser, including determination of glucose, total protein, albumin, creatine kinase, gamma-glutamyl transferase, aspartate aminotransferase, calcium, phosphorus and uric acid. The interfering effects of haemolysis varied depending on type of analyser, type of bird and the specific test. With the wet reagent chemistry analyser, the gamma-glutamyl transferase, phosphorus and uric acid analytes were most sensitive to haemoglobin interference, and the albumin, total protein and creatine kinase analytes were most resistant. With the dry slide reagent analyser, the gamma-glutamyl transferase, phosphorus, and albumin analytes were most sensitive to haemoglobin interference, and the glucose and aspartate aminotransferase analytes were most resistant. The effects of haemoglobin interference were not consistent from one type of chemistry analyser to another. The dry slide reagent analyser did not appear to resist the effects of haemoglobin interference better than the wet reagent analyser in this study. Our results suggest the need to construct interferographs for each chemistry analyser, species, and type of bird.

Comparison of measurements of canine plasma creatinine, glucose, proteins, urea, alanine aminotransferase, and alkaline phosphatase obtained with Spotchem SP 4430 and Vitros 250 analyzers

The suitability of the Spotchem 4430 benchtop biochemistry analyzer for canine blood samples was tested for creatinine, glucose, proteins, urea, alkaline phosphatases and alanine aminotransferase. Results obtained from whole blood and corresponding heparin plasma were identical except for proteins which were higher in plasma (n=10). Between series imprecision (n=10) was <5% for substrates and <10% for enzymes. Comparison of results from 100 Li-heparin samples with those measured with a Vitros 250 analyzer showed good correlation (r>0.93). The slopes of the Passing-Bablock's regression ranged from 0.90 to 1.20 and intercepts were low. The mean biases were low, except for creatinine for which the results obtained by Spotchem (Jaffe reaction) were about 20 micromol/L higher than with the Vitros (enzymatic reaction). The results of this study show that the Spotchem analyzer is suitable for use in canine whole blood or plasma when small numbers of tests are to be performed and large analyzers are not available.

Comparison of amylase and lipase activities in serum and plasma of dogs

BACKGROUND

Amylase and lipase activities are most often determined in serum, although heparinized plasma is more convenient to obtain and is used for many routine biochemical analyses.

OBJECTIVE

The purpose of this study was to compare amylase and lipase activities in serum and plasma of dogs and to determine whether either specimen type is acceptable for analysis.

METHODS

Serum and heparinized plasma were obtained from 101 randomly selected dogs and analyzed in parallel for alpha-amylase and lipase. Results were compared using Passing-Bablock regression, Bland-Altman difference plots, and correlation analysis.

RESULTS

There was a high correlation between the results obtained from serum and those from plasma. Regressions (with 95% confidence intervals in parentheses) were as follows: lipase(plasma) = 0.984 (0.976/0.995) Chi lipase(serum) - 0.9 (2.9/0.7) (r =.999); a-amylase(plasma) = 1.003 (0.977/1.032) Chi alpha-amylase(serum) - 1.9 ( 20.7/23.3) (r =.991). Mean differences (serum - plasma) were 8 U/L and 4 U/L for lipase and alpha-amylase, respectively. Classification of results as normal or abnormal did not differ according to specimen type.

CONCLUSION

In dogs, lipase and alpha-amylase activities can be determined with the same level of accuracy in serum and in heparinized plasma.

Creatinine in the Dog: A Review

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.

Effects of hemolysis on serum chemistry analytes in ratites

Since hemolysis has been a common problem in submitted ratite serum samples, a study was performed to determine interference by hemolysates. Nine chemistry analytes including glucose, total protein, albumin, creatine kinase (CK), gamma-glutamyl transferase (GGT), aspartate aminotransferase (AS7), calcium (Ca), phosphorus, and uric acid were evaluated on a wet reagent analyzer (Ciba Corning Express 550) and on a dry slide reagent analyzer (VetTest 8008). In emus, increasing hemoglobin concentrations increased total protein, albumin, and CK for both analyzers. With increasing hemoglobin concentrations, the Ciba Corning 550 analyte values were increased for AST, Ca, and uric acid and decreased for glucose and phosphorus, the opposite effect was seen in values from the VetTest 8008. GGT levels were variable or sometimes undetectable. Changes in ostrich analytes with hemolysis were similar to emus using the same analyzer. The effects of serum hemolysis often differed in magnitude and direction between the two chemistry analyzers. Interferographs were constructed to aid in rapid assessment of the effects of hemolysis on submitted serum samples.

Effects of haemolysis, lipaemia, bilirubinaemia and fibrinogen on protein electropherogram of canine samples analysed by capillary zone electrophoresis

The possible interference of haemolysis, lipaemia, bilirubinaemia and fibrinogen on capillary zone electrophoresis of canine samples were studied. Solutions of haemoglobin, lipid and bilirubin were prepared and mixed with serum aliquots to make up samples containing different concentrations of the putative interferent substance. In addition, samples of serum and plasma were assayed to assess the influence of fibrinogen. Haemolysis and lipids produced a change in electropherogram morphology giving an interference peak located in the beta-2 region when haemoglobin was increased, and in the alpha-2 region when lipids were increased. A rise in concentration of these interferents caused an increase in the beta and alpha-2 fractions respectively, and a decrease in the other fractions. Bilirubin did not alter morphology but gave an increase in the albumin and alpha-1 and a decrease in the alpha-2 and beta-2 fractions. No differences were found between serum and plasma samples, and fibrinogen did not produce any additional peak.