INFLUENCE OF SAMPLING METHOD ON WHOLE BLOOD IONIZED CALCIUM VALUES

1989 ◽  
Vol 71 (Supplement) ◽  
pp. A418 ◽  
Author(s):  
I. CONSTANT ◽  
B. BENETEAU ◽  
B. JUST ◽  
E. DELVA ◽  
M. VAUBOURDOLLE ◽  
...  
Keyword(s):  
Whole Blood ◽  
Sampling Method ◽  
Ionized Calcium

Comparison of hypertonic and isotonic reference electrode junctions for measuring ionized calcium in whole blood: a clinical study

1993 ◽  
Vol 39 (6) ◽  
pp. 1082-1085 ◽  
Author(s):  
P W Masters ◽  
R B Payne
Keyword(s):  
Serum Albumin ◽  
Whole Blood ◽  
Organic Anion ◽  
Reference Electrode ◽  
Ionized Calcium ◽  
Serum Chloride ◽  
Wide Range ◽  
Clinical Measurements

Abstract We measured ionized calcium concentrations in whole blood from 91 patients who had no clinical or biochemical evidence of disturbed calcium homeostasis and who had a wide range of serum albumin concentrations. We used both a standard Ciba-Corning 634 analyzer, which has a membrane-restricted saturated KCl reference electrode bridge, and a modified instrument with a 150 mmol/L NaCl bridge. After adjusting the externally standardized values from each instrument for their least-squares regressions on pH, there was a significant correlation between ionized calcium and albumin only with the standard analyzer. In contrast, only values from the modified instrument correlated with serum chloride; this was not explained by ionic strength or organic anion interferences. We conclude that there is unlikely to be any major advantage in using a membrane-restricted isotonic NaCl reference electrode for in vitro clinical measurements, although it may be of value for in vivo monitoring. The importance of measuring serum albumin when using most commercial ionized calcium analyzers is emphasized.

Effect of storage on measurement of ionized calcium in serum of uremic patients.

1985 ◽  
Vol 31 (2) ◽  
pp. 287-289 ◽  
Author(s):  
N I Nikolakakis ◽  
A M De Francisco ◽  
R S Rodger ◽  
E Gaiger ◽  
T H Goodship ◽  
...  
Keyword(s):  
Whole Blood ◽  
Room Temperature ◽  
Ionized Calcium ◽  
Measured Concentration ◽  
Analytical Variance ◽  
Serum Ionized Calcium ◽  
Uremic Patients ◽  
Serum Storage

Abstract We studied, in 70 acidotic and non-acidotic uremic patients, the analytical variance in serum ionized calcium as related to duration and temperature of storage. Storage of serum or whole blood at 4 degrees C for as long as 6 h did not significantly alter the measured concentration of ionized calcium in the serum. Storage at room temperature for 6 h, or longer at 4 degrees C or -20 degrees C, resulted in inaccuracies in 39 to 79% of the samples of serum and in 38 to 92% of the samples of whole blood. These errors were not negated by correcting the values for ionized calcium to a pH of 7.40. Indeed, corrected values for calcium were even more unreliable in acidotic patients. We conclude that samples from uremic patients should be analyzed for ionized calcium within 2 h, or within 6 h if stored at 4 degrees C.

Dry electrolyte-balanced heparinized syringes evaluated for determining ionized calcium and other electrolytes in whole blood

1991 ◽  
Vol 37 (10) ◽  
pp. 1730-1733 ◽  
Author(s):  
J Toffaletti ◽  
P Ernst ◽  
P Hunt ◽  
B Abrams
Keyword(s):  
Whole Blood ◽  
Cellular Metabolism ◽  
Ionized Calcium ◽  
Blood Collection ◽  
Heparin Concentration ◽  
Incomplete Filling ◽  
Blood Collection Tubes

Abstract By analyzing whole blood containing no anticoagulants (uncoagulated whole blood) immediately after collection, we evaluated the relative changes in the concentrations of ionized calcium and other electrolytes in whole blood collected in dry heparinized syringes and in serum prepared from blood collected in evacuated blood-collection tubes. Using these dry heparinized syringes, we collected and analyzed whole blood that contained either 33 or 13 int. units of lithium heparin or 40 int. units of electrolyte-balanced heparin per milliliter of blood. We evaluated the effects both of these heparins at different concentrations of ionized calcium and of the incomplete filling of the syringes. We conclude that: (a) when analyzed within 2-3 min after collection, uncoagulated whole blood provides ionized calcium results unaffected by anticoagulants or cellular metabolism; (b) the preparation of serum unpredictably changes ionized calcium; (c) the use of dry electrolyte-balanced heparin virtually eliminates the interference in ionized calcium concentrations between 0.9 and 1.6 mmol/L; and (d) incomplete filling of electrolyte-balanced heparinized syringes produces no effect in syringes two-thirds full (60 int. units/mL heparin concentration) and a small effect in syringes one-third full (120 int. units/mL heparin).

Critical analytical and clinical aspects of ionized calcium in neonates.

1989 ◽  
Vol 35 (10) ◽  
pp. 2027-2033 ◽  
Author(s):  
J Wandrup
Keyword(s):  
Calcium Homeostasis ◽  
Whole Blood ◽  
Clinical Symptoms ◽  
Maternal Blood ◽  
Ionized Calcium ◽  
Preterm Neonates ◽  
Clinical Aspects ◽  
Cross Sectional ◽  
Significant Data ◽  
Neonatal Hypocalcemia

Abstract Clinical diagnosis in neonates is often based primarily on biochemical data, because clinical symptoms are difficult to assess and inconclusive. A knowledge of the validity of the data would therefore seem very important. Practical technical assessments lead me to conclude that measurement of ionized calcium at actual pH in anaerobic capillary samples of whole blood, currently practicable, is an easy and optimal laboratory analysis when biologically significant data are required for assessment of acute disturbances in calcium homeostasis of neonates. Values are given for ionized calcium, describing the relations in cord and maternal blood in uncomplicated pregnancies at term. Recent published cross-sectional and longitudinal reference values for ionized calcium, measured during the first weeks in healthy full-term and preterm neonates, seem to provide a new basis for the diagnosis and management of early neonatal hypocalcemia.

Preparation and use of serum-based material as control and calibrator in evaluating ion-selective electrodes for calcium.

1985 ◽  
Vol 31 (8) ◽  
pp. 1349-1352 ◽  
Author(s):  
J Toffaletti ◽  
K M Lee
Keyword(s):  
Whole Blood ◽  
Calcium Ion ◽  
Ionized Calcium ◽  
Ion Selective Electrodes ◽  
Control Material ◽  
Blood Samples ◽  
Valid Comparison ◽  
Whole Blood Samples

Abstract We analyzed 93 sera and 81 whole-blood samples, plus several aqueous materials and one serum-based material as controls, with two analyzers for ionized calcium (Radiometer ICA 1 and AVL 980). On 16 days, comparisons of results for patients' samples were good, with nearly all between-instrument differences (delta Ca2+) of samples being within 0.04 mmol/L. On 12 days, comparisons were mediocre, with the delta Ca2+ of samples usually 0.04 to 0.10 mmol/L. The control material that most consistently indicated the direction and magnitude of the delta Ca2+ of patients' samples was the serum-based control. Adjustment of results for samples from patients, based on the delta Ca2+ of the serum control on the same day, substantially improved comparisons between instruments. Our findings suggest that the use of a serum-based calibrator provides the most valid comparison between different calcium-ion analyzers and reliably indicates when electrode replacement is needed.

scholarly journals Effect of starvation and sampling time on plasma alkaline phosphatase activity and calcium homeostasis in the rat

1989 ◽  
Vol 23 (1) ◽  
pp. 53-58 ◽  
Author(s):  
C. S. Thompson ◽  
D. P. Mikhailidis ◽  
D. S. Gill ◽  
J. Y. Jeremy ◽  
J. L. Bell ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Whole Blood ◽  
Calcium Concentration ◽  
Sampling Time ◽  
Ionized Calcium ◽  
Plasma Calcium Concentration ◽  
Plasma Alkaline Phosphatase ◽  
25 Oh Vitamin D

The effect of starvation and sampling time on plasma alkaline phosphatase activity, total plasma calcium concentration and whole blood ionized calcium concentration was determined in the rat. Starvation caused a significant fall in total and ionized calcium concentrations as well as in alkaline phosphatase activity. These changes were accompanied by a fall in whole blood pH and an increase in the anion gap and a decrease in urinary excretion of calcium. These indices were restored to normal following refeeding. There was no change in serum 25-OH vitamin D concentrations following starvation for 3 days. Alkaline phosphatase activity showed a pattern compatible with the presence of a circadian rhythm when sampling took place between 0800 and 1800 h. Total and ionized calcium concentrations did not show such a rhythm when animals were fed the present diet.

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