TY - JOUR
T1 - Free calcium in serum. I. Determination with the ion specific electrode and factors affecting the results
AU - Ladenson, J. H.
AU - Bowers, G. N.
PY - 1973/1/1
Y1 - 1973/1/1
N2 - Free (ionic) calcium in human serum was measured with a commercially available ion specific electrode, together with a saturated KCl salt bridge, a saturated calomel reference electrode, and a direct reading electrometer. Effects of sodium, potassium, and magnesium on the electrode values for calcium were assessed and a rationale demonstrated for the use of calcium standards containing 140 mmol of NaCl, 5 mmol of KCl, and 0.55 mmol of MgCl2 per liter. Trypsin, triethanolamine, and heparin bind calcium; therefore, their use is to be avoided. Variability is greatly decreased if the serum is from a fasting subject and if the collection tube is completely filled, transported on ice, and handled anaerobically. The range of free calcium for 86 apparently healthy adults was 1.175-1.375 mmol/liter when measured at 25°C. The precision (coefficient of variation) of duplicates was 0.6%; the long term precision 2.0%.
AB - Free (ionic) calcium in human serum was measured with a commercially available ion specific electrode, together with a saturated KCl salt bridge, a saturated calomel reference electrode, and a direct reading electrometer. Effects of sodium, potassium, and magnesium on the electrode values for calcium were assessed and a rationale demonstrated for the use of calcium standards containing 140 mmol of NaCl, 5 mmol of KCl, and 0.55 mmol of MgCl2 per liter. Trypsin, triethanolamine, and heparin bind calcium; therefore, their use is to be avoided. Variability is greatly decreased if the serum is from a fasting subject and if the collection tube is completely filled, transported on ice, and handled anaerobically. The range of free calcium for 86 apparently healthy adults was 1.175-1.375 mmol/liter when measured at 25°C. The precision (coefficient of variation) of duplicates was 0.6%; the long term precision 2.0%.
UR - http://www.scopus.com/inward/record.url?scp=0015794015&partnerID=8YFLogxK
U2 - 10.1093/clinchem/19.6.565
DO - 10.1093/clinchem/19.6.565
M3 - Article
C2 - 4705172
AN - SCOPUS:0015794015
VL - 19
SP - 565
EP - 574
JO - Clinical Chemistry
JF - Clinical Chemistry
SN - 0009-9147
IS - 6
ER -