Potassium as Mineral – Rich Food Sources, Functions, Deficiency & Daily Requirements

Health Care Guide on Potassium (K) functions in Human Body, Absorption, Excretion, Regulation facts & disease – Hyperkalemia & Hypokalaemia in word/ .doc / ppt / .pdf format

POTASSIUM (K):

Potassium is the major intracellular cation. It is widely present in the body fluids and tissues.

Sources:

• It is most widely distributed in vegetables.

Daily requirement:

• Adult : 2-4 gms
• children : 1-3 gms .Serum level 3.5-5.1mmol/L

Absorption:

• Potassium is easily absorbed.
• Potassium exhibits a tendency to diffuse against concentration gradient from the intracellular to the extracellular fluid. The sodium pump transports potassium into the cells.

Excretion:

• It is excreted in the urine. The amount excreted is dependent on the sodium intake.
• It is excreted via the gastrointestinal tract, saliva, pancreatic and intestinal juices and faeces.
• Small amounts are lost via skin as sweat.

Function:

• Some of the functions of potassium are same as those of sodium.
• Serum potassium concentration does not vary appreciably in response to water loss or retention.
• Cellular uptake of potassium is stimulated by insulin.
• Helps in maintaining Acid-base balance. A reciprocal relationship exists between potassium and hydrogen ions. As acidosis develops, potassium ions are disposed from the cells in order to maintain electroneutrality. Thus potassium is involved in acid-base balance.
• It is important in cardiac and muscular functions. Too high or too low concentration of potassium may have life-threatening consequences.
• Helps in enzyme action. An enzyme such as pyruvate kinase requires K+ as a cofactor.
• Like sodium, it is also involved in neurotransmitter.

Applied aspects:

• Extracellular levels of potassium are measured in serum.
• Hemolysis and allowing the serum sample to stand for very long, produces changes in the potassium values So, the sample should be analyzed as soon as possible.

Clinical manifestations:

Hyperkalemia:

Causes:-

• The kidneys may not be able to excrete a potassium load when glomerular filtrate is low. Acidosis aggravates the problem.
• In addison’s disease and adrenalectomy, high levels of potassium are observed.
• Potassium is released from damaged cells. 

Clinical symptoms :-

• Muscle weakness
• Hyperkalaemia can cause sudden death as cardiac arrest is the first manifestation. It lowers the resting membrane potential, shortens cardiac action potential and increases the velocity of repolarization. It is therefore necessary to be alert.     

Management :-

• Infusion of insulin and glucose.
• Infusion of calcium gluconate may also counteract the effect of hyperkalemia.
• Dialysis is sometimes necessary.

Hypokalaemia :

Causes :-

• Gastrointestinal losses, diarrhoea, vomiting or surgical fistula.
• Renal diseases, administration of diuretics and increased aldosterone production.
• Administration of diuretics and corticosteroids.
• Alkalosis which shifts potassium from the extracellular fluid to the intracellular fluid   

Clinical symptoms:-

• Neuromuscular weakness and hypotonia
• Cardiac arrhythmias, digoxin toxicity and changes in ECG.
• Impaired concentrating ability of the kidneys leading to polyuria and polydypsia.
• Metabolic alkalosis

Management :-

• Oral administration of salts is given in an enteric coating because potassium salts are unpleasant.
• Intravenous potassium can be given.

Applied aspect:-

• Intravenous potassium should be given slowly and under ECG monitoring except in extreme cases.

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