Hypokalemia in patients with cancer

Hypokalemia is defined as blood potassium levels below 3.5 mEq/lt; levels below 2.5 mEq/lt are considered severe hypokalemia and should be treated early and under strict monitoring of the patient, as it is associated with complications such as paralytic ileus, arrhythmias, and death [1].

Hypokalemia can occur in 40% of cancer patients, [2] due to cancer-specific causes, non-cancer-specific causes, or a combination of both [3]. Non-cancer-specific causes include chemotherapy, which can cause hypokalemia as an adverse effect. Specific cancer causes of hypokalemia include ectopic adrenocorticotropic hormone-secreting tumors and acute myeloid leukemia [4,5].

It should be noted that oncologic patients may have problems with oral intake due to nausea, mucositis, etc., so intravenous administration is often necessary [6].

Based on the above, institutional recommendations are presented in tables 1–3 on how to perform potassium loads in ambulatory oncologic patients treated at the Instituto Oncológico Fundación Arturo López Pérez.

It is important to note that these recommendations apply only to hypokalemia detected in the outpatient area and do not apply to patients with kidney disease. Intravenous infusion is the only recommended administration route, preferably through a central venous catheter or port-a-cath at less than 20 mEq/hour to avoid irritation and pain. Premix solutions are preferred when appropriate, but avoid adding additional drugs or solutions to them; use glucose-free solutions only to avoid hypokalemia due to metabolic effects. Monitoring serum potassium 2-3 hours after the infusion is recommended to assess whether another dose is required.

In cases where it is necessary to add magnesium to the solution, it should be done at the rate of 1 ampoule of magnesium sulfate 25%/5mL = 1.25 grams.

In mild to moderate hypokalemia without the need for urgency, oral administration at high doses (60 to 80 mEq/day) is recommended, which in this protocol were converted for the intravenous route (20 to 40 mEq/L), adjusted to a maximum administration of 3 hours by peripheral venous route, considering that post-infusion potassium should be measured once supplemented a maximum of 40 to 60 mEq before administering new potassium infusion rate are also relevant to avoid phlebitis and decreasing the morbidity associated with this procedure [7,8,9].

Concomitant administration of magnesium is used to ensure optimal levels, as deficiency of this electrolyte may exacerbate potassium depletion, making ongoing potassium correction refractory [13].

Conclusions

Hypokalemia is an electrolyte disorder that frequently affects cancer patients for multiple reasons. It can often be a serious and life-threatening disorder if not adequately treated. Diagnosis, proper treatment, and monitoring are essential. We would like to emphasize that the rate of infusion and the concentration of potassium administered must be taken into account for correction in order to avoid side effects due to incorrect administration.