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==Introduction==
==Introduction==
'''Hypokalaemia''' occurs most commonly in cats secondary to [[Chronic Renal Failure]] and is the most common electrolyte abnormality seen in small animal practise. [[Potassium]] is important for '''nervous''' and '''muscle conduction''', especially in cardiac muscle. It also has '''metabolic functions'''. The classic clinical sign is '''ventroflexion of the neck''', with the cat unable to raise its head properly. It is also reported in calves following dehydration and diarrhoea. The consequence is cardiac arrest following ventricular dissociation.
'''Hypokalaemia''' occurs most commonly in cats secondary to [[Chronic Renal Failure|chronic renal failure]] and is the most common electrolyte abnormality seen in small animal practice. [[Potassium]] is important for '''nervous''' and '''muscle conduction''', especially in cardiac muscle. It also has '''metabolic functions'''. The classic clinical sign is '''ventroflexion of the neck''', with the cat unable to raise its head properly. It is also reported in calves following dehydration and diarrhoea. The consequence is cardiac arrest following ventricular dissociation.
==Aetiology==
==Aetiology==
Low potassium levels in the blood can be due to:
Low potassium levels in the blood can be due to:
'''Decreased uptake'''
This is normally the result of prolonged low-potassium '''fluid therapy''' (Hartmanns) administration in the anorexic cat. It does not usually cause disease in itself, instead exacerbating signs of existing hypokalaemia.
:This is normally the result of prolonged low-potassium '''fluid therapy''' (Hartmanns) administration in the anorexic cat. It does not usually cause disease in itself, instead exacerbating signs of existing hypokalaemia.
'''Increased loss'''
Potassium can be lost from the '''gastrointestinal tract''' or [[Urinary System - Anatomy & Physiology|'''urinary system''']]. [[Diarrhoea]] results in the direct loss of potassium in the '''faeces'''. '''Vomiting''' results in both direct loss and excretion of potassium from the '''kidneys''' secondary to '''metabolic alkalosis'''. Hypokalaemia is also a common consequence of [[Chronic Renal Failure|chronic renal failure]], it is caused by increased loss of potassium in the urine coupled with '''polyuria, anorexia and low dietary intake'''. Low levels of potassium can be a primary cause of kidney dysfunction, this condition is known as 'potassium depletion nephropathy'. Clinical signs normally improve following dietary supplementation. The excessive or long-term use of [[Diuretics Effects on Kidneys - Anatomy & Physiology|'''non-potassium sparing diuretics''']] (frusemide) can also increase loss of potassium into the urine. Rarely, the endocrinopathy known as '''hyperaldosteronism''' ''aka'' Conn's syndrome may also cause potassium loss by increasing secretion from the distal convoluted tubule in the kidney.
:Potassium can be lost from the '''gastrointestinal tract''' or [[Urinary System - Anatomy & Physiology|'''urinary system''']]. [[Diarrhoea]] results in the direct loss of potassium in the '''faeces'''. '''Vomiting''' results in both direct loss and excretion of potassium from the '''kidneys''' secondary to '''metabolic alkalosis'''. Hypokalaemia is also a common consequence of [[Chronic Renal Failure|chronic renal failure]], it is caused by increased loss of potassium in the urine coupled with '''polyuria, anorexia and low dietary intake'''. Low levels of potassium can be a primary cause of kidney dysfunction, this condition is known as 'potassium depletion nephropathy'. Clinical signs normally improve following dietary supplementation. The excessive or long-term use of [[Diuretics Effects on Kidneys - Anatomy & Physiology|'''non-potassium sparing diuretics''']] (frusemide) can also increase loss of potassium into the urine. Rarely, the endocrinopathy known as '''hyperaldosteronism''' ''aka'' Conn's syndrome may also cause potassium loss by increasing secretion from the distal convoluted tubule in the kidney.
'''Trans-cellular shift'''
Shifting of potassium from the '''extracellular fluid''' into the '''intracellular fluid''' in high quantities or for prolonged periods can cause low serum levels and hypokalaemia. This is caused by an '''metabolic or respiratory alkalosis''' and the subsequent compensation, '''insulin therapy, hyperthyroidism and hypokalaemic polymyopathy in the Burmese cat'''.
:Shifting of potassium from the '''extracellular fluid''' into the '''intracellular fluid''' in high quantities or for prolonged periods can cause low serum levels and hypokalaemia. This is caused by an '''metabolic or respiratory alkalosis''' and the subsequent compensation, '''insulin therapy, hyperthyroidism and hypokalaemic polymyopathy in the Burmese cat'''.
'''Drug-induced'''
'''Insulin therapy, fluid therapy, bicarbonate therapy, B2-agonists, laxatives and nephrotoxic drugs''' can all cause low serum potassium levels.
:'''Insulin therapy, fluid therapy, bicarbonate therapy, B2-agonists, laxatives and nephrotoxic drugs''' can all cause low serum potassium levels.
'''Oral supplementation''' is more suitable for '''mild or chronic''' cases, it is quite unpalatable and therefore not suitable for some anorexic or vomiting cats. Improvement of clinical signs should be evident after 1-3 days. Potassium levels should be measured approximately every two weeks until serum levels stabilise.
'''Oral supplementation''' is more suitable for '''mild or chronic''' cases, it is quite unpalatable and therefore not suitable for some anorexic or vomiting cats. Improvement of clinical signs should be evident after 1-3 days. Potassium levels should be measured approximately every two weeks until serum levels stabilise.
'''Intravenous supplementation''' is more suitable in '''acute or severe''' cases. IV potassium preparations are not licensed in small animals therefore '''potassium chloride administration with IVFT''' is the treatment of choice. As a result of the fluid therapy, hypokalaemia may worsen before improving (as the existing potassium is diluted down), therefore acute cases require very close monitoring during treatment (severe muscle weakness and subsequent respiratory arrest can occur). The maximum rate of potassium infusion should not be exceeded. Treatment should take effect within hours and at this point oral supplementation should be used if possible.
'''Intravenous supplementation''' is more suitable in '''acute or severe''' cases. IV potassium preparations are not licensed in small animals therefore '''potassium chloride administration with IVFT''' is the treatment of choice. As a result of the [[:Category:Fluid Therapy|fluid therapy]], hypokalaemia may worsen before improving (as the existing potassium is diluted down), therefore acute cases require very close monitoring during treatment (severe muscle weakness and subsequent respiratory arrest can occur). The maximum rate of potassium infusion should not be exceeded. Treatment should take effect within hours and at this point oral supplementation should be used if possible.
There should be no concurrent administration of glucose or [[Insulin|insulin]] therapy as this reduces serum potassium levels by increasing uptake into the intra-cellular fluid.
There should be no concurrent administration of glucose or [[Insulin|insulin]] therapy as this reduces serum potassium levels by increasing uptake into the intra-cellular fluid.
'''Hyperkalaemia should always be avoided'''. This is achieved by closely monitoring potassium levels, administering potassium slowly and at the correct dose, and by checking renal function prior to treatment. Treatment with ACE-Inhibitors and potassium-sparing diuretics should also be avoided.
'''Hyperkalaemia should always be avoided'''. This is achieved by closely monitoring potassium levels, administering potassium slowly and at the correct dose, and by checking renal function prior to treatment. Treatment with ACE-inhibitors and potassium-sparing diuretics should also be avoided.
==Prognosis==
==Prognosis==
{{review}}
[[Category:Vascular Fluid]]
[[Category:Vascular Fluid]]
[[Category: To Do - Siobhan Brade]]
[[Category:Expert Review]]