TESTS CARRIED OUT UNDER CLINICAL BIOCHEMISTRY
In clinical biochemistry department, the following tests are carried out:
Electrolytes are substances that become ions in solution and acquire the capacity to conduct electricity. The electrolytes that are measured include sodium, potassium and chloride using the 9180 electrolyte analyzer.
- Collection of sample in the lithium heparin bottle.
- Spin with the centrifuge at 3000 revolution per minute for 5 minutes (to separate the plasma from the blood cells).
- Transfer serum into the venial cup using the automatic pipette.
- Start the machine until it is ready
- Open the machine door
- Introduce your serum to the machine there by allowing it to come in contact with the probe
- Wipe the probe and close the door
- The probe aspirates the serum, analyzes it and gives out the results within 2 minutes.
Reference ranges for electrolyte test is as follows;
Electrolytes Reference Range
UREA AND CREATININE IN CLINICAL BIOCHEMISTRY
Urea is determined for the evaluation of renal function. The test is often used together with the determination of creatinine for differentiation between prerenal and postrenal azotaemia on the basis of the urea/creatinine ratio. Other indications for determination of urea are end-stage renal failure and determination in dialysis patients as the urea concentration is representative for protein breakdown and provides information on the metabolic status. These are products of osmoregulation and are assayed using the reflotron; they also have their different strips. The reference range of urea and creatinine are 10-50mg/dl and 0.5-1.1mg/dl respectively.
After application to test strip, the sample flows into the reaction zone, in the case of blood after separation of the erythrocytes from the plasma. The urea contained in the sample is hydrolyzed to ammonium carbonate from which ammonia is expelled due to the alkaline buffering. This leads to the partial colour change of a buffered indicator to green /blue, the intensity of which is proportional to the urea concentration of the sample:
(NH2)2 CO + H2O Urease 2NH3 + CO2
NH2 + indicator (yellow) NH4+ + indicator (blue)
At a temperature of 37Oc the depth of colour formed is measured at 642nm and the urea concentration displayed after about 190 seconds in mg/dl depending on how the instrument has been set.
Blood sample is taken in the lithium heparin tubes or Ethylene Diamine tetra acetic tube.
Testing Procedure for CLINICAL BIOCHEMISTRY
Additional materials required: reflotron instrument; reflotron pipette and pipette tips or capillary pipette, controls, usual laboratory equipment for collection of blood.
- Switch on the instrument (reflotron).
- When the display shows “ready”, remove your test strip from the container.
- Unwrap the strip taking care not to bend it.
- Using the reflotron pipette, draw sample material into the pipette (avoiding bubbles) and apply a drop to the centre of the red application zone being careful so as not touch the application zone with the pipette tip. (The required volume of specimen for application is 30Nl).
- With the sliding cover or flap open, place the test strip on the guide within 15 sec and slide forward horizontally until it locks into place. Close the sliding cover or flap.
- The instrument displays urea/ creatinine to confirm that it has correctly read in the test-specific magnetic code. The display shows the number of seconds left before the result is displayed. The concentration is calculated automatically from the readings taken using a function and conversion factors that are entered in the instrument via the magnetic strip on the underside of each test strip. The concentration is displayed in mg/dl or mmol/l depending on whether the instrument has been set to show conventional or S.I un its.
- Remove the used test strip from the reflotron and dispose of it according to your laboratory’s procedure.
Adults <65 years <50mg/dl or <8.3mmol/l
>65 years <71 mg/dl or <11.9mmol/l