Disturbances of potassium concentration (chemical pathology) Flashcards
What roles do potassium do? (5)
-Hormonal secretion
-Maintenance of trans membrane potential.
-Regulation of acid base balance
-Cellular growth, protein synthesis.
-Contraction of muscle, CVS, CNS and respiratory function.
How do we obtain potassium balance (3)
•Na+/K+ (ATPase) transporter- Found in all cells and it throws 3Na+ out of the cell and 2K+ in.
•H+/K+ (ATPase) transporter- Found in the GIT and renal tubules, throws H+ out and K+ into the cell.
•Na+/K+/2Cl- (co transporter)- found in the loop of henle.
How does aldosterone stimulate potassium excretion? (2)
It stimulates it directly by increasing the active secretion of potassium in the distal tubule.
Indirectly by stimulating the active reabsorption of sodium in the distal tubule and collecting ducts.
Abnormalities in potassium balance occur as a result of what?
Depletion, excess or shift btwn compartments (ECF and ICF).
Acidosis leads to how much levels of potassium?
Hyperkalaemia (high levels)
Common cause of hypokalemia
Diuretic use
Other causes of hypokalaemia
-Diarrhoea
-Vomiting
-Mineralocorticoid excess
-Glococorticoid excess
-Metabolic alkalosis
Which potassium abnormality is a medical emergency?
Hyperkalaemia
What are the symptoms of hyperkalaemia? (3)
-Weakness, fatigue, shortness of breath.
ECG changes in hypokalaemia (3)
-T-wave flattening
-ST-segment changes
-Prolonged U-wave
ECG changes in hyperkalaemia (3)
-Peaked T-wave
-Prolonged PR segment
-Prolonged QRS complex
What are the causes of hyperkalaemia? (4)
-Pseudo hyperkalaemia (prolonged tourniquet during venepuncture, haemolysis)
-Excessive intake (Excessive IV, orally)
-Redistribution from ICF to ECF.
-Decreased excretion.