Potassium Examination Procedure 

1.Purpose of Examination: To lay down standard operating procedure for serum Potassium by ISE Method in Biochemistry section of LSSTH, Bhavnagar.

2.Principle: Ion Selective Electrode Method.

3.Performance: Linearity – 2.0-11.6 mEq/L Precision – It is determined from 2 runs per day with two replicates per run for 20 days on two AFT 300 Electrolyte Analyser

4.Primary Sample: Plasma or serum sample_collection_manual

5.Patient Preparation: Verbal consent of patient should be taken before collecting blood sample.

6.Type of Container: Plain Vaccute with no additive

7.Required Equipment: Centrifuge, Electrolyte auto analyzer

8.Safety Precaution: Follow the universal work precautions.

9.Calibration Procedure: Instrument performs auto calibration every four hours Manual calibration is done on following circumstances:

1. After instrument repair
2. After new reagent lot
3. After each replacement of the Fluidpack
4. QC data not satisfactory - QC outlier

10.Procedural Steps: Centrifuge the blood sample ,Open the sample door of the instrument, than hold the Vacutte under the probe to be aspirated .

11.Quality Control Procedure: The Laboratory runs Internal Quality control level 1, level 2 & level 3 once a day. Monthly L-J charts are reviewed & for any QC outlier root cause analysis are done & corrective actions are taken according to error. Participated in RIQAS programme. RIQAS reports is reviewed and if any result go outlier, than root cause analysis is done & corrective actions are taken according to error.

12.Interferences & Cross-Reactions: It is recommended that the Blood sample should be obtained without a tourniquet. Also Lipemia and Hemolysis interferes.

13.Principle of Procedure for Calculating Results: Membrane potential are caused by the permeability of certain types of membranes to selected anions or cations. The potential produced at the membrane –solution interface is proportional to the logarithm of the ionic activity or concentration of Potassium Ion

14.Biological Reference Interval: 3.5- 5.1 mEq/L

15.Reportable interval of patient examination results: 2.8-6.2 mEq/L

16.Instruction for determining Quantitative results when a results is not within the measurement Rerun the sample and correlate clinically

17.Stability of sample Serum or plasma-At Room temperature18°–28°C (64°–82°F) stability ≤ 24 hours CSF- At Refrigerated 2°–8°C (36°–46°F) stability 3 days

18.Storage of sample 2-8° C for 1 days (Retention period for re-examination and/or additional tests is 24 hrs. at (2-8° C).

19.Reagent Storage and stability Unopened reagents is stable until expiration date when store at 2-8°c.Reagent stability is 30 days if reagent is uncapped and onboard.

20.Turn around time (TAT) 6.0 hours after collection, in case of emergency 2.0 hours.

21.Critical Value:

• Adult : 2.8 - 6.2 mEq/L
• Newborn : 2.8 - 7.8 mEq/L

22.Laboratory Interpretation:

• High potassium levels are seen in:
• Renal failure, Oliguria, Metabolic acidosis or respiratory acidosis, Hemolysis, Urinary obstruction.
• Low potassium levels are seen in:
• Diarhoea, Vomiting, Severe burns and Malabsorption

23.Potential source of variation:

1. Expiry of Kit
2. Instrumental Error
3. Presence of interfering source
4. Instrumental Error
5. Reagent contamination
6. Storage condition not proper

24.Reagent Handling Remove any air bubbles present in the reagents with a new applicator stick, or allow the reagents to sit at the appropriate storage temperature to allow the bubbles to dissipate. To minimize volume depletion, do not use a transfer pipette to remove bubbles

25.REFERENCE:

1. Friedman R. Young D.S.:Effects of Disease on Clinical Laboratory Tests, AACC Press, Washington, D.C. 1989
2. Komberg A., Horecker B.L.: Methods in Enzymology, Colowickand Kaplan, edes. Vol. 1, Academic Press, New York 323, 1955.
3. Batheimal W., Czock R., Enzymatic determination of glucose in the blood, cerebrospinal fluid and urine, Klin.Wochenncschr., 40:585, 1962.
4. Tietz Textbook of Clinical Chemistry, W.B. saunders, Philadelphia, PA, 3 rd edition 1999, pp. 776-82.
5. Westgard J. Barry P., cost Effective Quality Control: Managing the Quality and productivity of Analitycal Processes, AACC press, Washington, D.C. 1986
6. Tietz Textbook of Clinical Chemistry, W.B. saunders, Philadelphia, PA, 3 rd edition 1999, pp. 1815.
7. Young D.S., Effects of Drugs on Clinical Laboratory Tests, AACc Press Washington, D.C., 1990.
8. Document EP3-T:”Guidelines for Manufacturers for Estabilishing Performance Claims for Clinical Chemical Methods, Replication Experiment Evaluation”, National Committee for Clinical Laboratory Standards, Villanova, Pa, 1982.
9. Roche Ise Indirect Na K Cl05883962001c501V13.0
10. NABL 112 effective from 01/06/2019