Electrolyte disturbance

Question 1

Discuss causes of hyperkalaemia

Answer 1

Pseudo

Excessive intake

• dietary
• iatrogenic

Shift from intracellular to extra

• exercise
• hyperkalemic periodic paralysis
• hypertonocity: hyperglycaemia, hypteronic saline, mannitol
• insulin deficiency
• metabolic acidosis
• rhabdo
• succinylcholine
• tumor lysis syndrome

Reduced extretion

• AKI
• CKD
• Adrenal deficiency
• – addisons
• –heparin
• –NSAIDS
• renal tubule hyporesponsiveness/resistance to mineralcorticoids

Question 2

Discuss clinical signs of hyperkalaemia

Answer 2

Peaking of T-wave at 5.5-6 with shortening of the QT
> 6 prolonged PR and QRS complex duration
As it rises further P wave is lost adn QRS merges into T causes sin wave. Leads to standstill or VF

effect of hyperkalaemia on the myocardium is influenced by acidosis, hyponatraemia and hypocalcemia all of which increase neuromuscular finding of hyperkalaemia

Question 3

Discuss treatment of hyperk

Answer 3

Cardiac stabilisation
Calcium salts antagonise the cardiac effects of high extracellular potassium through unclear mechanisms. They do not lower K. Care needs to be taken if on digoxin as can lead to dig toxicity

Shift into cells
Insulin and B agonist such as salbutamol activate the Na/K atapase and shift K into cells
–10units of actrapid with 50mls 50% dextrose – lowers by approxim 1mmol peak onset one hour and last several hours
– 10-20mg of neb salbuatmol

Excretion

• frusemide or thiazide diuretics
• resonium
• HD

Question 4

Discuss causes of hypokalemia

Answer 4

Inadequate Intake

Shift from extracellular fluid to intracellular fluid

• chatecholamines, beta receptor agonists, insulin
• hypokalaemic periodic paralysis
• hypothermia
• respiratory and metabolic alkalosis

Excessive excretion 
Renal
-diuretics 
-fanconi syncdrome 
-hypomag
-mineralcorticoid excess 
-RTA (proximal and distal)
GIT 
-diarrhoea
-laxative abuse 
-vomiting 
-dialysis

Question 5

Discuss clinical features of hypokalaemia

Answer 5

Mild and slowly developing may be asymptomatic

GIT:
– constipation with progression to paralytic ileus
MSK
-generalised weakness, cramps paresthesias and myalgias
-loss of deep tendo reflex, rhabdo and skeletal and respiratory muscle paralysis

ECG:

• ST depression
• reduced T wave
• prominent U

KUB

• impaired urinary concentrating ability
• nocturia/polyuria