Hypokalemia
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55 y/o male
CC: chronic diarrhea
Farmer in La Trinidad, Benguet
Noted progressive weakness for the past
weeks
Na
Cl
K
Blood Test
140 meq/L
110 meq/L
2.0 meq/L
Hypokalemia
• Urine potassium: 15 meq/L
pH
pCO2
HCO3
Arterial Blood Gas
7.28
39 mmHg
16
Diagnostic approach to hypokalemia
Urinary K+
excretion
<15
mmol/d
>15
mmol/d
Assess acidbase status
Assess K+
secretion
Diagnostic approach to hypokalemia
Assess acidbase status
Metabolic
acidosis
Metabolic
alkalosis
Lower
gastrointestin
al K+ loss
Remove diuretic
use, vomitting and
K+ loss via sweat
Diagnostic approach to hypokalemia
Assess K+
secretion
Transtubular
K+
concentration
gradient > 4
Transtubular
K+
concentration
gradient < 2
Acid-base
status
Na+ wasting
nephropathy,
osmotic diuresis,
diuretic
Diagnostic approach to hypokalemia
Acid-base
status
Metabolic
acidosis
Metabolic
alkalosis
Diabetic
ketoacidosis,
proximal RTA, distal
RTA, amphotericin B
Hypertension?
Diagnostic approach to hypokalemia
Hypertension?
YES
NO
Mineralocorticoid excess,
Liddle’s
syndrome
Vomiting,Bartter’s
syndrome, exclude
diuretic use,
hypomagnesemia
Significance of Urinary K levels
• This can be established after eliminating
decreased intake and intracellular shift as
potential causes of hypokalemia
• Appropriate response to K+ depletion is to
excrete less than 15 mmol/d of K+ in the
urine, due to increased reabsorption and
decreased distal excretion
• This is exemplified by the diagnostic approach
shown previously
Adverse medical implications
• More severe hypokalemia may lead to
progressive weakness, hypoventilation (due to
respiratory involvement involvement, and even
complete paralysis
• Impaired muscle metabolism and blunted
hyperemic response to exercise leads to
rhabomyolysis
• Leads to prolonged PR interval, decreased voltage
and widening of the QRS complex, with increased
risk of ventricular arrhythmia
Symptoms of Hypokalemia
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Palpitations
Skeletal muscle weakness or cramping
Paralysis, paresthesias
Constipation4
Nausea or vomiting
Abdominal cramping
Polyuria, nocturia, or polydipsia
Psychosis, delirium, or hallucinations
Depression
Signs of Hypokalemia
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Signs of ileus
Hypotension
Ventricular arrhythmias
Cardiac arrest
Bradycardia or
tachycardia
• Premature atrial or
ventricular beats
• Hypoventilation,
respiratory distress
• Respiratory failure
• Lethargy or other mental
status changes
• Decreased muscle
strength, fasciculations,
or tetany
• Decreased tendon
reflexes
• Cushingoid appearance
(eg, edema)
Treatment
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ECG monitoring
Establish IV access
Assess respiratory status
Infuse potassium chloride, since his serum potassium
is < 2.5 meq/L, in other cases oral is the preferred
route for potassium repletion because it is easy to
administer, safe, inexpensive, and readily absorbed
from the GI tract
• Check serum Mg levels since it is difficult to restore K
if the former is low