Veterinary Clinical Biochemistry and Laboratory Diagnosis-II

Estimation of Potassium

ESTIMATION OF SERUM POTASSIUM (Turbidimetric method)

Principle:

Potassium ions react with sodium tetraphenyl boron to produce a colloidal suspension, which is stabilized in a special matrix. The extent of turbidity is measured in terms of absorbance and is proportional to potassium concentration.

                          Tetraphenyl Boron + K⁺ → White turbidity

Reagents:

1. Boron reagent 2. Potassium standard (5 mmol/l)

Procedure:

Pipette into two clean, dry test tubes labelled standard (S), and test (T) as follows:

S.No	Reagents	S (ml)	T (ml)
1.	Standard Potassium	0.02	-
2.	Serum	-	0.02
3.	Boron (K+) Reagent	1.00	1.00
4.	Deionised water	1.50	1.50

Mix well, wait for 5 minutes at room temperature and read the absorbance of standard (S) and test (T)

against distilled water at 620nm or with a red filter in a photoelectric colorimeter within 10 minutes.

Calculations :

Potassium (mmol/L) =                   O.D (T)

                                                        ----------- x 5

                                                           O.D (S)

Result:

The potassium content of given serum = mmol / l or meq / l

Clinical Significance:

• Play an important role in the maintenance of normal water distribution between cells and plasma and correct environment for muscle contraction.
• An increased in serum potassium may occur in renal failure, anuria and severe oliguria.
• Decrease in serum potassium is more commonly seen in severe vomiting, diarrhoea and hyperadrenalism.
• During attacks of paralysis.
• Apathy and muscle weakness are the predominant features of low potassium levels.