Hypokalaemia

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Normal range: 3·5 to 5·3mmol/L

These guidelines do not apply to critically ill patients or to patients at risk of refeeding syndrome. For refeeding syndrome please see Policy for prevention and management of refeeding syndrome in adults

General management
  • Replace potassium losses
  • Identify and treat underlying cause where possible
    • Loop/thiazide diuretics – consider combination with a potassium-sparing diuretic
    • Vomiting and diarrhoea-
    • Intracellular potassium shifts, eg post-operation, coronary ischaemia, critical illness
    • Refeeding (see link in heading above)
    • Hypomagnesaemia

NB – if hypokalaemia remains unexplained, more specialised investigations may be appropriate. Advice may be obtained from the Biochemistry Department or the patient’s Consultant.

Drug therapy/treatment options

Caution should be used in patients with renal insufficiency or when ACE Inhibitors or potassium-sparing diuretics are being administered concomitantly.

Always seek advice from a Consultant Renal Physician for the treatment of patients with severe renal impairment.

Do not give potassium supplements if plasma K+ is greater than 5mmol/L.

Patients in the following categories should be aggressively replaced: cardiac instability or otherwise unstable, symptomatic patients, patient with refeeding syndrome (see link in heading above), patients with bowel disease, GI losses and ileus.

Suggested starting doses

1. For plasma K+ 3·0 to 3·5mmol/L (approximate potassium deficit 200mmol) and low risk of complications:

Sando-K® 2 tablets 3 times daily

Notes

  • Each Sando-K® tablet contains 12mmol of potassium and 8mmol of chloride.
  • Monitor plasma K+ after 2 days treatment then twice weekly until stable.
  • Once plasma K+ stable or if plasma K+ > 4·5mmol/L, reassess requirement for supplementation.

2. For plasma K+ 2·5 to 2·9mmol/L (approximate potassium deficit 200 to 400mmol) and low risk of complications:

Sando-K® 3 tablets 3 times daily

Notes

  • Each Sando-K® tablet contains 12mmol of potassium and 8mmol of chloride
  • Monitor plasma K+ daily until plasma K+ > 2·9mmol/L and then manage as in 1 above.

3. Plasma K+ < 2·5mmol/L or cardiac arrhythmia (approximate deficit > 400mmol):

1000ml sodium chloride 0.9% or glucose 5% with 40mmol potassium over at least four hours, depending on fluid balance/ tolerance.

As glucose may reduce serum potassium concentrations, during initial replacement it may be preferable to use premixed infusions that are glucose-free.

Intravenous potassium supplementation

Intravenous supplements are indicated if patients cannot eat, are unlikely to absorb oral potassium or have profound hypokalaemia.

Where possible use prepared infusion bags containing either potassium chloride 20mmol/L or potassium chloride 40mmol/L. These are available as:

Strength of potassium chloride

 Infusion fluids

10mmol in 500ml

20mmol in 1 litre

Potassium chloride 0·15% w/v

 

 

 

 

Sodium chloride 0·9% w/v

Glucose 5% w/v

X

Glucose 4% w/v with sodium chloride 0·18% w/v

X

Glucose 5% w/v with sodium chloride 0·45% w/v

X

Glucose 5% w/v with sodium chloride 0·9% w/v

X

 

Strength of potassium chloride

 Infusion fluids

20mmol in 500ml

40mmol in 1 litre

Potassium chloride 0·3% w/v

Sodium chloride 0·9% w/v

Glucose 5% w/v

X

Glucose 4% w/v with sodium chloride 0·18% w/v

X

Glucose 5% w/v with sodium chloride 0·9% w/v

X

Administration should be via a volumetric infusion pump. The infusion site should be checked on a 4-hourly basis for signs of redness and inflammation.

The rate of infusion should not normally exceed 10mmol K+/hour.  Continuous ECG monitoring is essential for infusion rates exceeding 20mmol per hour, due to the risk of serious arrhythmias or cardiac arrest.  Prescription of rates above 10mmol K+/hour should be completed by a member of the senior medical team.

Potassium concentrations above 40mmol/L should be given via a central venous catheter and must be prescribed by a member of the senior medical team.

Urea and electrolytes should be checked every 12 to 24 hours or more often as required. Blood glucose should also be monitored.