Hypokalemia (low potassium) Therapy Calculator
Potassium related content
Hypokalemia (defined as a serum potassium level of less than 3.5
mmol/L) is one of the most common electrolyte abnormalities
encountered in clinical practice with more than 20% of hospitalized patients
affected and approximately 40% of ICU patients.
Hypokalemia reflects either total body potassium depletion
or redistribution from extracellular fluid to intracellular
fluid without potassium depletion.
The most common causes include:
- Nonrenal losses (urine K+ < 20 mmol/L):
- Renal losses (urine K+ ≥ 20 mmol/L):
Loop diuretics (furosemide, bumetanide, torsemide).
Osmotic diuresis e.g. uncontrolled diabetes.
- Mineralocorticoid excess
- Primary and secondary hyperaldosteronism
- Magnesium depletion
- Transcellular Shifts:
Acute catecholamine surges,
Note: Increased potassium loss (through the kidneys or gastrointestinal
tract) is the most common cause of hypokalemia.
- Initially, determine if the patient is symptomatic or arrhythmias
are present. Also look for weakness or palpitations, ECG changes, severe
hypokalemia (less than 2.5 mEq/L (mmol/L), rapid-onset hypokalemia, or
if the patient has underlying heart disease or cirrhosis. This will help determine the acuity of the interventions
- Perform a history and physical examination to look for relevant
clinical clues including offending medications, conditions, possible GI
losses, and whether
or not factitious/spurious hypokalemia is present. Most cases of hypokalemia-induced rhythm disturbances occur in
individuals with underlying heart disease.
- Determine if the lower potassium levels were caused by a
transcellular shift (managed by treating the underlying condition or
removing the offending agent) or a decrease in total body potassium. A
history of paralysis, hyperthyroidism, or use of insulin or beta
agonists suggests possible transcellular shifts leading to
- Evaluating the urine potassium,
fractional excretion of potassium (FEK) and the
Potassium Gradient can help differentiate between renal and nonrenal
causes of hypokalemia.
- Urinary potassium levels higher than 20 mmol/L are suggestive of
renal causes and levels lower than 20 mmol/L are suggestive of nonrenal
Identification and treatment of concurrent hypomagnesemia:
Magnesium depletion reduces the intracellular potassium concentration
and causes renal potassium wasting.
The diagnosis should be confirmed with a repeat serum
potassium measurement. Other laboratory tests include serum
glucose and magnesium levels, urine electrolyte and creatinine
levels, and acid-base balance.
Current Potassium Level
[Value below 3.9 mEq/L (mmol/L
Describe current symptoms of hypokalemia
[Severe symptoms include
: cardiac arrhythmias,
pronounced muscle weakness, paralysis, or ECG changes
ECG changes may include: prominent U
wave, flattened or inverted T waves, ST segment depression, T and U wave
fusion giving appearance of QT interval prolongation.
ventricular tachycardia and/or fibrillation, torsades de pointes.]
Select any that apply
Patient is able to take oral
Magnesium level is in the normal range?
to cardiac arrhythmias by several mechanisms including increased
cardiac automaticity, slowed conduction, and delayed ventricular
repolarization, predominantly in patients with ischemic heart
disease or on digitalis.
Symptoms of mild hypokalemia:
- Respiratory difficulty
- Paralytic ileus
- Leg cramps
Examples of symptoms by system due to hypokalemia:
- ECG changes
- Arrhythmias (especially
ventricular arrhythmias), PEA, Aystole.
- Sudden death
Polyuria due to decreased concentrating ability
Chloride-depletion metabolic alkalosis
Increased risk of nephrolithiasis
Altered gastrointestinal motility (nausea, vomiting, constipation,
Worsening of hepatic encephalopathy
Respiratory acidosis secondary to respiratory muscle weakness
- Insulin resistance and impairment in insulin release
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