Canterbury DHB


IV fluid and electrolyte replacement

Many patients treated with intensive high dose chemotherapy and or stem cell transplant can, over a period of several days, become potassium depleted requiring long periods of high dose potassium supplementation to correct plasma and total body stores. Sodium overload is likely to be an issue as well. Contributing factors include potassium-free IV fluid replacement, poor oral intake and GI losses.

The normal daily requirement for sodium is 100-120 mmol and potassium 40–80 mmol.


For those patients unable to maintain required oral fluid intake, e.g. post transplant - but specifically not hyperhydration regimens or those on TPN:

Those requiring 2 L/day should have:

This would better meet normal daily requirements of sodium and potassium.

If further IV fluids are required (e.g. diarrhoea) then a further litre of 0.9% sodium chloride +/- 30 mmol potassium could be given.

In This Section

Magnesium Deficiency

Potassium Administration

Magnesium Deficiency

Magnesium depletion may occur in patients receiving cyclosporin and/or tacrolimus, aminoglycosides, e.g. gentamicin/tobramycin, amphotericin B, pentamidine, diuretics, e.g. frusemide/thiazide, cisplatin and excessive IV fluids. Patients receiving these medications should have magnesium levels regularly monitored plus receive adequate magnesium supplementation to maintain normal concentrations of serum magnesium.

side effects of hypomagnesaemia include hypocalcaemia, hypokalaemia, muscle cramping, weakness, tremors, confusion, disorientation, arrythmias, seizures, cessation of bone growth with decreased osteoblast and osteoclast activity, peripheral vitamin D resistance and resistance to parathyroid hormone, augmentation of cyclosporin induced nephrotoxicity and augmentation of gentamicin induced ototoxicity.

Supplementation may be oral, or IV if severe.

Side effects of magnesium supplementation may include diarrhoea, hypotension, bradycardia, flushing, sweating, nausea, double vision and circulatory collapse. Magnesium may cause diarrhoea so begin at a lower dose and increase as tolerated. As magnesium causes diarrhoea and aluminium (contained in mylanta) causes constipation, mylanta may be more appropriate in patients prescribed magnesium only and who are experiencing diarrhoea. Magnesium oral preparations are not funded on the pharmaceutical schedule.

Potassium Administration

The intravenous administration of potassium carries certain dangers including that of cardiac arrhythmias secondary to hyperkalaemia. At higher concentrations IV potassium is a local irritant and should be administered through a central line. To manage hypokalaemia, see Hospital Healthpathways Hypokalaemia.

Currently the most concentrated IV potassium formulation available in the hospital for use outside Intensive Care is pre-made bags of 10 mmol potassium chloride in 100 mL 0.29% sodium chloride. These can be given via central line over 30 minutes. Options for the treatment of hypokalaemia include:

About this Canterbury DHB document (65815):

Document Owner:

Not assigned (see Who's Who)

Issue Date:

January 2019

Next Review:

January 2022


Note: Only the electronic version is controlled. Once printed, this is no longer a controlled document. Disclaimer

Topic Code: 65815