Disturbances of potassium concentration (chemical pathology)

Question 1

What roles do potassium do? (5)

Answer 1

-Hormonal secretion
-Maintenance of trans membrane potential.
-Regulation of acid base balance
-Cellular growth, protein synthesis.
-Contraction of muscle, CVS, CNS and respiratory function.

Question 2

How do we obtain potassium balance (3)

Answer 2

•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.

Question 3

How does aldosterone stimulate potassium excretion? (2)

Answer 3

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.

Question 4

Abnormalities in potassium balance occur as a result of what?

Answer 4

Depletion, excess or shift btwn compartments (ECF and ICF).

Question 5

Acidosis leads to how much levels of potassium?

Answer 5

Hyperkalaemia (high levels)

Question 6

Common cause of hypokalemia

Answer 6

Diuretic use

Question 7

Other causes of hypokalaemia

Answer 7

-Diarrhoea
-Vomiting
-Mineralocorticoid excess
-Glococorticoid excess
-Metabolic alkalosis

Question 8

Which potassium abnormality is a medical emergency?

Answer 8

Hyperkalaemia

Question 9

What are the symptoms of hyperkalaemia? (3)

Answer 9

-Weakness, fatigue, shortness of breath.

Question 10

ECG changes in hypokalaemia (3)

Answer 10

-T-wave flattening
-ST-segment changes
-Prolonged U-wave

Question 11

ECG changes in hyperkalaemia (3)

Answer 11

-Peaked T-wave
-Prolonged PR segment
-Prolonged QRS complex

Question 12

What are the causes of hyperkalaemia? (4)

Answer 12

-Pseudo hyperkalaemia (prolonged tourniquet during venepuncture, haemolysis)
-Excessive intake (Excessive IV, orally)
-Redistribution from ICF to ECF.
-Decreased excretion.