Page 53 - Read Online

Berardi et al. J Cancer Metastasis Treat 2019;5:79 I http://dx.doi.org/10.20517/2394-4722.2019.008 Page 21 of 33

The treatment of hypokalemia depends on symptoms and their severity. It is focused on preventing life-
threatening complications and removing the underlying cause [Figure 5].

In patients with mild or moderate hypokalemia (serum potassium levels of 3.0-3.5 mEq/L), potassium
oral supplementation should be preferred to intravenous, in order to avoid an iatrogenic hyperkalemia.
A daily dose of 60-80 mEq of potassium chloride is recommended. However, it is important to monitor
serum potassium concentration in order to adjust treatment doses accordingly. In the case of chronic
hypokalemia refractory to oral supplementation, the addition of potassium-sparing diuretics (amiloride
and spironolactone) should be considered [132] .

In asymptomatic patients with severe hypokalemia (serum potassium level of < 3.0 mEq/L), an oral
potassium supplementation with potassium chloride 40 mEq every 3-4 h should be considered [133] .
Otherwise, in symptomatic patients with a life-threatening complication, or in patients unable to take
oral drugs, intravenous potassium (10-20 mEq/h, able to increase serum potassium level an average of
0.25 mEq/h) is recommended [134] . Continuous ECG monitoring is recommended in patients with
arrhythmias, digitalis toxicity, and history of cardiac ischemia. In patients with renal failure, the doses
should be reduced and serum potassium level monitored frequently. Refractory hypokalemia might depend
on the presence of concomitant electrolyte disorders, such as hypomagnesemia, which should be investigated
and treated when present [135] .

When hypokalemia is secondary to tumor activity, treating the cancer is necessary, in addition to
symptomatic therapy for hypokalemia, in order to prevent the recurrence of symptoms.

Patients with carcinoid syndrome should receive somatostatin analog in order to inhibiting hormonal
hyper-secretion and improve symptoms [136] . When hypokalemia depends on primary aldosteronism,
unilateral adrenalectomy is preferred to mineralocorticoid receptor antagonists [137] .

In the case of ectopic ACTH secretion, a complete resection of the tumor should be preferred, when
possible. Other treatment options, such as steroid-synthesis inhibitors (metyrapone, mitotane, trilostane,
ketoconazole, and aminoglutethimide) and glucocorticoid receptor antagonists (mifepristone), are available
to control severe hypercortisolemia [138] . In patients with severe (Grades 2-3) diarrhea due to anticancer
drugs or radiotherapy, a symptomatic treatment with probiotics, loperamide, and in refractory cases
octreotide should be administered in order to prevent hypokalemia [139] .

Hyperkalemia
Definition and clinical implications
Hyperkalemia is defined as an increased serum potassium concentration (> 5.5 mEq/L). According to
potassium level, three different grades of severity are described: mild hyperkalemia (5.1-6.0 mEq/L),
moderate hyperkalemia (6.1-7.0 mEq/L), and severe hyperkalemia (> 7.0 mEq/L), which represents a life-
[140]
threatening condition .

Causes
Several causes might induce hypokalemia in cancer patients [108] :
(1) Cancer: several conditions related to cancer might induce hyperkalemia. Tumors with high proliferative
index such as leukemia and small-cell lung carcinomas can result in lysis syndrome after specific anticancer
treatment, inducing hyperkalemia.

(2) Cancer treatment: chemotherapeutic agents, such as platinum derivatives, might cause renal injury,
which can lead to hyperkalemia.