Laboratory

Calcium: programming in a semi-auto biochemistry analyzer

Calcium

Calcium occupies about 2% of the total body weight in an adult. Out of that, about 99% is found in the bones. You can measure the value of calcium in your body by an OCPC method or Arsenazo III method.

Functions of calcium

  • Intracellular activities such as muscle contraction and glycogen metabolism.
  • Extracellular activities such as blood clotting, bone mineralization, glycogen metabolism, and the transmission of nerve impulses.

A decrease in the calcium level can be an indication of osteoporosis, under dialysis, hyperparathyroidism, and defective intestinal absorption. Similarly, an increase in the calcium level can be an indication of hyperparathyroidism,  malignant diseases, etc.

Normal range (approximate value) of calcium

1. Serum

  • Children (10 days- 2 years):- 9 to 11 mg/dl
  • Children (2 years – 12 years):- 8.8 to 10.8 mg/dl
  • Adult (12 years – 60 years):- 8.4 to 10.2 mg/dl
  • Adult (60 years – 90 years:- 8.8 to 10.2 mg/dl
  • Adults (> 90 years):- 8.2 – 9.6 mg/dl

2. Urine

  • 75 – 300 mg/24 hours (during normal food intake)

Handling

  • Wear an apron and surgical gloves before carrying out the measurement.
  • Look for the expiry date of the reagents during purchase and measurement time. Suppliers tend to give you reagent kits with a low expiry interval.
  • Once you open the reagent bottles, the lifespan will decrease. So, look in your reagent kit literature for that.
  • Bring the reagents and samples to room temperature before you can carry out any measurement.
  • Always store reagents in the refrigerator when not in use.

Working principle (OCPC method)

1. Principle reaction 

Calcium reacts with o-cresolphtalein complexone (OCPC) in an alkaline medium to form a purple-colored calcium-o-cresolphthalein-complex. The intensity of the color is directly proportional to the concentration of calcium in the sample.

2. Sample preparation

The table shown below for calcium measurement is valid for tulip, accurex, and analyticon. So, if you have the reagent kit of any other company, then there can be minor fluctuation in the method.

If you have two reagents, then make a working solution out of them. The ratio of their composition will be given in the literature of your reagent kit or the reagent bottle. Else, a single reagent can also be found based on the company. In that case, that single reagent kit will act as a working solution for you.

For making a sample test, mix the sample with the working solution. Similarly, for making a reagent blank (accurex), feed the working solution directly into the semi-auto biochemistry analyzer. In the case of analyticon and tulip, replace the sample/calibrator with the same volume of distilled water, and add it to the working solution.

Always remember that sipping volume < sample volume + reagent volume. So that means, make sufficient sample volume to feed into the semi-auto biochemistry analyzer. Else, it will suck up the air and will give the fault reading.

If the concentration of calcium is too high (out of range/ non-linear), then dilute the sample with 0.9% NaCl or distilled water at the ratio of 1:y. Finally, when you get the result, multiply the value with the dilution factor (1+y).

Programming of calcium in a semi-auto biochemistry analyzer (OCPC method)

 o-cresolphthalein complexone, OCPC, calcium

Working principle (Arsenazo III method )

1. Principle reaction

Calcium reacts with Arsenazo III  at neutral pH, to form a blue colored complex. The intensity of the color is directly proportional to the concentration of calcium in the given sample.

2. Sample preparation

The table shown below for calcium measurement is valid for spinreact and diasys. So, if you have the reagent kit of any other company, then there can be minor fluctuation in the method.

For making a sample test, mix the sample with the working solution. Similarly, for making a reagent blank, replace the working solution with the same volume of distilled water and then feed into the semi-auto biochemistry analyzer.

If the concentration of calcium is too high (out of range/ non-linear), then dilute the sample with 0.9% NaCl or distilled water at the ratio of 1:y. Finally, when you get the result, multiply the value with the dilution factor (1+y).

Programming of calcium in a semi-auto biochemistry analyzer (Arsenazo III method)

Arsenazo III, calcium

 

 

 

 

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