Calcium with Arsenazo III (1,8-Dihydroxy-3,6-disulpho-2,7-
naphthalene-bis (azo)-dibenzenearsonic acid), at neutral pH, yields a
blue colored complex.
The intensity of the colour formed is proportional to the calcium
concentration in the sample1,2,3
PRINCIPLE OF THE METHOD
Calcium with Arsenazo III (1,8-Dihydroxy-3,6-disulpho-2,7-
naphthalene-bis (azo)-dibenzenearsonic acid), at neutral pH, yields a
blue colored complex.
The intensity of the colour formed is proportional to the calcium
concentration in the sample1,2,3
.
CLINICAL SIGNIFICANCE
Calcium is the most abundant and one of the most important minerals
in the human body. Approximately 99% of body calcium is found in
bones.
A decrease in albumin level causes a decrease in serum calcium. Low
levels of calcium are found in hypoparathyroidism,
pseudohypoparathyroidism, vitamin D deficiency, malnutrition and
intestinal malabsortion.
Among causes of hypercalcemia are cancers, large intake of vitamin D,
enhaced renal retention, osteoporosis, sarcosidosis, thyrotoxicosis,
hyperparathyroidism1,6,7
.
Clinical diagnosis should not be made on a single test result; it should
integrate clinical and other laboratory data.
STORAGE AND STABILITY
All the components of the kit are stable until the expiration date on the
label when stored tightly closed at 2-8ºC, protected from light and
contaminations are prevented during their use.
Do not use reagents over the expiration date.
Signs of reagent deterioration:
- Presence of particles and turbidity.
- Blank absorbance (A) at 660 nm
0,50.
ADDITIONAL EQUIPMENT
- SPIN640 / SPIN640Plus Autoanalyzer.
- General laboratory equipment (Note 1, 2)
.
SAMPLES
- Serum or plasma1
: Separated from cells as rapidly as possible. Blood
anticoagulants with oxalate or EDTA are not acceptable since these
chemicals will strongly chelate calcium.
- Urine1
: Collect 24 hour urine specimen in calcium free containers. The
collecting bottles should contain 10 ml of diluted Nitric acid (50% v/v).
Record the volume.
Dilute a sample 1/2 in distilled water. Mix. Multiply results by 2 (dilution
factor).
Stability of the samples: Calcium is stable 10 days at 2-8ºC.
QUALITY CONTROL
Control sera and calibrators are recommended to monitor the
performance of assay procedures: SPINTROL H Calibrator,
SPINTROL H Normal and Pathologic (Ref. 1002011, 1002120 and
1002210).
If control values are found outside the defined range, check the
instrument, reagents and technique for problems.
Each laboratory should establish its own Quality Control scheme and
corrective actions if controls do not meet the acceptable tolerances.
