Potassium, the Major Intracellular Cation

Potassium is the primary intracellular cation. It is also an integral part of the transmission of nerve impulses.  It participates in the sodium-potassium pump in the body. 

Unhemolyzed serum should be used because hemolysis will markedly increase the potassium values because potassium is present in large amounts inside the cell.

Clinical Significance

1.      Hyperkalemia – increased concentration of potassium in the bloodstream. It’s found in the following conditions:

•         Decreased renal excretion

•         Acute or chronic renal failure

•         Hypoaldosteronism

•         Addison’s disease

•         Diuretic

·         Cellular shift

•         Acidosis

•         Muscle/cellular injury

•         Chemotherapy

•         Leukemia

•         Hemolysis

Increased intake

             Oral or IV potassium replacement therapy

-          Artifactual

                        Sample hemolysis

                        Thrombocytosis

                        Prolonged tourniquet use of excessive fist clenching

2.      Hypokalemia – decreased concentration of potassium in the blood stream, seen in the following conditions:

            GI loss

                        - Vomiting

                        - Diarrhea

                        - Gastric suction

                        - Intestinal tumor

                        - Malabsorption

                        - Cancer therapy

                        - Large doses of laxatives

          Normal values:

                           K = 3.5-5.3

•         Plasma and serum: 3.4 – 5.0 mmol/L

•         Urine: 25 -125 mmol/L

Clinical Electrolytes - Cations and Anions

Electrolytes are amphoteric substances, meaning they could be positively or negatively charged. The positively charged ions are called cations, and the negatively charged -anions.

Examples given here are those electrolytes which are commonly tested in the clinical laboratory.

Positively charged ions are called CATIONS :

1. Potassium - intracellular
2. Magnesium - intracellular
3. Calcium - extracellular
4. Sodium - extracellular

Negatively charged ions are called ANIONS :

1. Chloride - extracellular
2. bicarbonate - extracellular
3. inorganic phosphorus - intracellular

The determination of these electrolytes are very significant in the assessment of several diseases like diabetic ketoacidosis, water-electrolyte status , and many more.