ABSTRACT
OBJECTIVE: To explore diurnal variation in blood ionized calcium, sodium, potassium, and chloride concentrations and pH in pregnant dairy cows. ANIMALS: 14 dairy cows in their third or later pregnancy approximately 6 weeks before expected parturition. PROCEDURE: Throughout a 24-hour period, blood samples were taken at 2-hour intervals and analyzed for ionized calcium (iCa2+), potassium (K+), sodium (Na+), and chloride (Cl-) concentrations and pH. Paired t-tests were used to compare initial and final values. Circadian changes were tested by use of repeated-measures ANOVA. Additionally, a nonparametric analysis was performed for each animal to determine minimal and maximal values for the variables. RESULTS: Significant differences were not detected between initial and final values of any variable. Repeated-measures ANOVA indicated significant diurnal fluctuations in all variables. With the exception of Cl- concentration, nonparametric analysis of individual values also revealed significant changes over time. CONCLUSIONS AND CLINICAL RELEVANCE: The magnitude of daily fluctuations does not make it necessary to standardize time of sample collection for routine diagnostic examination of blood iCa2+, Na+, and Cl-concentrations and pH. However, it may be important to standardize time of sample collection in comparative studies in which more discrete differences may be identified.
Subject(s)
Calcium/blood , Cattle/blood , Chlorides/blood , Circadian Rhythm/physiology , Potassium/blood , Sodium/blood , Analysis of Variance , Animals , Blood Chemical Analysis/veterinary , Cattle/physiology , Female , Hydrogen-Ion Concentration , Ion-Selective Electrodes/veterinary , Pregnancy , Reference Values , Statistics, NonparametricSubject(s)
Acid-Base Equilibrium , Blood Preservation , Calcium/blood , Swine/blood , Animals , Female , Hydrogen-Ion Concentration , Pregnancy , Time FactorsABSTRACT
The stability of blood ionized calcium (Ca2+) and acid-base variables in equine, bovine, ovine, and canine venous blood samples (n = 15, in each group) stored at 4 C for 3, 6, 9, 24, or 48 hours was studied. Variables included blood Ca2+ and standard ionized calcium (Ca2+ corrected to pH 7.4) concentrations, pH, blood carbon dioxide and oxygen tensions, base excess, bicarbonate concentration, and total carbon dioxide content. Results indicate that storage of blood samples at 4 C for up to 48 hours, despite appreciable acid-base changes, is associated with less than 1.5% change in equine, bovine, and ovine blood Ca2+ concentrations. Similar changes were observed in canine blood during the first 9 hours' storage. After 24 and 48 hours' storage, clinically relevant decrease (10.5 and 15.5%) in canine blood Ca2+ concentration was measured. Therefore, Ca2+ concentration in equine, bovine, and ovine venous blood samples stored up to 48 hours, and in canine blood samples stored up to 9 hours at 4 C is of diagnostic use.