Skip to main content
Symptom
dx.
Menu
Clinical Reference
Approaches
I have a symptom
Management
I know the diagnosis
Orthopedic Injuries
Fractures & dislocations
Calculators
Clinical calculators
Practical Skills
ECG
Interpretation guide
POCUS
Bedside ultrasound
Procedures
Step-by-step guides
Resuscitation
ACLS / PALS / NRP
Learn
Blog
Articles & updates
Deep Dive
In-depth clinical reviews
About
Our mission
Symptom
dx.
Clinical Reference
Approaches
I have a symptom
Management
I know the diagnosis
Orthopedic Injuries
Fractures & dislocations
Calculators
Clinical calculators
Practical Skills
ECG
Interpretation guide
POCUS
Bedside ultrasound
Procedures
Step-by-step guides
Resuscitation
ACLS / PALS / NRP
Learn
Blog
Articles & updates
Deep Dive
In-depth clinical reviews
About
Our mission
Get Started
Menu
Clinical Reference
Approaches
I have a symptom
Management
I know the diagnosis
Orthopedic Injuries
Fractures & dislocations
Calculators
Clinical calculators
Practical Skills
ECG
Interpretation guide
POCUS
Bedside ultrasound
Procedures
Step-by-step guides
Resuscitation
ACLS / PALS / NRP
Learn
Blog
Articles & updates
Deep Dive
In-depth clinical reviews
About
Our mission
Loading...
Hypokalemia
Cardiovascular Presentations
Abdominal aortic aneurysm
Acute coronary syndrome (NSTEMI)
Acute coronary syndrome (STEMI)
Acute decompensated heart failure
Acute limb ischemia
Acute mesenteric ischemia
Aortic dissection
Aortic stenosis
Atrial fibrillation and flutter
Bradyarrhythmia and heart block
Cardiac arrest
Deep vein thrombosis
Myocarditis
Pericarditis
Pulmonary embolism
Stable angina
Superficial thrombophlebitis
Superior vena cava syndrome
Supraventricular tachycardia
Syncope (cardiogenic)
Unstable angina
Ventricular tachycardia
Respiratory Presentations
Acute bronchitis
Acute respiratory failure
Aspiration pneumonia
Asthma exacerbation
Bronchiolitis
Community-acquired pneumonia
COVID-19 pneumonia
COPD exacerbation
Croup
Croup (laryngotracheobronchitis)
Epiglottitis
Hemothorax
Hospital-acquired pneumonia
Pleural effusion
Pneumothorax (traumatic)
Pulmonary contusion
Spontaneous pneumothorax
Neurological Presentations
Bell's palsy
Benign paroxysmal positional vertigo
Brain abscess
Cauda equina syndrome
Cervical radiculopathy
Concussion (mild traumatic brain injury)
Encephalitis
Guillain-Barré syndrome
Hemorrhagic stroke (intracerebral)
Ischemic stroke
Lumbar radiculopathy
Malignant spinal cord compression
Migraine
Peripheral neuropathy (acute)
Retropharyngeal abscess
Schizophrenia (acute exacerbation)
Seizure (breakthrough:known epilepsy)
Seizure (first-time)
Spinal cord injury
Status epilepticus
Subarachnoid hemorrhage
Tension headache
Transient ischemic attack
Traumatic brain injury (moderate-severe)
Vestibular neuritis
Viral meningitis
Gastrointestinal Presentations
Acute appendicitis
Acute cholecystitis
Acute diverticulitis
Acute pancreatitis
Anal fissure
Choledocholithiasis and cholangitis
Clostridioides difficile colitis
Gastritis
Gastroenteritis (viral and bacterial)
Gastroesophageal reflux disease
Incarcerated or strangulated hernia
Inflammatory bowel disease flare
Large bowel obstruction
Lower GI hemorrhage
Peptic ulcer disease
Perforated viscus
Small bowel obstruction
Upper GI hemorrhage
Genitourinary and Reproductive Presentations
Acute prostatitis
Acute urinary retention
Ectopic pregnancy
Epididymitis
Orchitis
Ovarian torsion
Paraphimosis
Pelvic inflammatory disease
Priapism
Pyelonephritis
Renal laceration
Ruptured ovarian cyst
Testicular torsion
Tubo-ovarian abscess
Urinary tract infection (uncomplicated)
Urolithiasis (renal colic)
Vaginal bleeding (non-pregnant)
Infectious Disease Presentations
Acute sinusitis
Acute tonsillitis
Acute upper respiratory infection
Animal bite
Bacterial meningitis
Cellulitis
Conjunctivitis (bacterial)
Dental abscess
Endocarditis
Febrile neutropenia
Fournier gangrene
Hand-foot-mouth disease
Hepatitis (acute)
Herpes zoster
HIV-related illness
Human bite
Impetigo
Infected diabetic foot ulcer
Infectious mononucleosis
Influenza
Necrotizing fasciitis
Osteomyelitis
Otitis externa
Parasitic infection
Periorbital cellulitis
Peritonsillar abscess
Scabies
Sepsis
Septic arthritis
Spontaneous bacterial peritonitis
Tick-borne illness (Lyme disease)
Tinea infection
Tuberculosis
Viral exanthem
Wound infection
Trauma Presentations
Achilles tendon rupture
ACL and mceniscus tear
Ankle fracture
Ankle sprain
Burn
Calcaneus fracture
Cervical spine fracture
Clavicle fracture
Dental avulsion
Distal radius fracture
Drowning
Elbow fracture and dislocation
Electrical injury
Facial bone fracture
Facial laceration
Femur fracture
Fingertip amputation
Forearm fracture (radius and ulna)
Frostbite
Hand:finger laceration
Heat exhaustion
Heat stroke
Hip fracture
Humeral shaft fracture
Knee dislocation
Knee sprain
Lightning injury
Mandible fracture
Metacarpal fracture
Metatarsal fracture
Muscle strain
Nasal fracture
Non-accidental trauma
Orbital fracture
Patella fracture
Phalanx fracture (finger)
Proximal humerus fracture
Pulmonary contusion
Rib fracture
Rotator cuff tear (acute traumatic)
Scalp laceration
Scaphoid fracture
Shoulder dislocation
Skull fracture
Splenic laceration
Sternal fracture
Supracondylar pediatric fracture
Tendon laceration (hand:wrist)
Thoracic and lumbar spine fracture
Tibia:fibula fracture
Tibial plateau fracture
Toe fracture
Traumatic epistaxis
Traumatic hyphema
Toxicologic Presentations
Acetaminophen toxicity
Alcohol intoxication
Alcohol withdrawal
Anticholinergic toxicity
Anticoagulant overdose
Benzodiazepine overdose
Benzodiazepine:sedative overdose
Beta-blocker and calcium channel blocker toxicity
Carbon monoxide poisoning
Caustic ingestion
Digoxin toxicity
Drug eruption
Foreign body ingestion
Opioid intoxication
Opioid overdose
Opioid withdrawal
Organophosphate
Salicylate toxicity
Serotonin syndrome
Stimulant intoxication (cocaine, methamphetamine)
Tricyclic antidepressant overdose
Psychiatric Presentations
Acute anxiety
Acute psychosis
Agitation:behavioral emergency
Bipolar disorder
Conversion disorder
Major depressive episode
Neuroleptic malignant syndrome
Suicidal ideation and attempt
Musculoskeletal and Rheumatologic Presentations
Acute low back pain (mechanical)
Bursitis
Cervical radiculopathy
Costochondritis
Gout (acute)
Lumbar radiculopathy
Pseudogout
Tendinitis
Dermatology Presentations
Acute eczema (Eczema acute flare)
Allergic contact dermatitis
Erythema multiforme
Henoch-Schönlein purpura
Pressure injury
Psoriasis (acute flare)
Stevens-Johnson syndrome
Toxic epidermal necrolysis
Urticaria (acute)
Environmental and Exposure Presentations
Envenomation (snake, spider, insect)
High-altitude illness
Hypothermia
Hematologic and Oncologic Presentations
Acute chest syndrome
Coagulopathy
Hyperviscosity syndrome
Sickle cell crisis (vaso-occlusive)
Symptomatic anemia
Thrombocytopenia (severe)
Tumor lysis syndrome
Pediatric-Specific Presentations
Bronchiolitis
Croup
Emergency delivery
Febrile seizure
Kawasaki disease
Neonatal jaundice
Neonatal sepsis
Nursemaid's elbow
Pediatric fever 0 to 28 days
Pediatric fever 29 to 60 days
Pediatric fever 61 to 90 days
Pyloric stenosis
Slipped capital femoral epiphysis
Intussusception
Endocrine and Metabolic Presentations
Adrenal crisis
Diabetic ketoacidosis
Hypercalcemia
Hyperosmolar hyperglycemic state
Hypertensive emergency
Hypertensive urgency
Hypoglycemia
Myasthenia gravis crisis
Myxedema coma
Severe hyperkalemia
Severe hyponatremia
Thyroid storm
ENT and Maxillofacial Presentations
Acute laryngitis
Acute otitis media
Acute pharyngitis
Cerumen impaction
Epistaxis (anterior)
Nasal foreign body
Otitis externa
Tympanic membrane perforation
Ophthalmologic Presentations
Acute angle-closure glaucoma
Central retinal artery occlusion
Chemical eye injury
Corneal abrasion
Corneal ulcer
Globe rupture
Ocular foreign body
Orbital cellulitis
Retinal detachment
Obstetric Presentations
Hyperemesis gravidarum
Painful vaginal bleeding in pregnancy
Placenta previa
Placental abruption
Preeclampsia:eclampsia
Preterm labor
Threatened:inevitable:incomplete abortion
Systemic and Miscellaneous Presentations
Anaphylaxis
Angioedema
Cannabis-induced hyperemesis
Hypokalemia
POCUS
Procedures
Calculators
Resuscitation
ECG Guide
Back
Clinical Assessment Checklist
Browse categories and answer follow-up questions to refine your symptom profile.
Approach to the Critical Patient
Immediate priorities
Life-threatening presentations requiring immediate action
▶
Cardiac arrest or malignant arrhythmia
▶
Ventricular tachycardia or ventricular fibrillation
Torsades de pointes from QTc prolongation
Defibrillation plus IV KCl and magnesium simultaneously
Respiratory failure from diaphragmatic weakness
▶
SpO2 < 90% with shallow respirations
Rising PaCO2 indicating impending failure
Early intubation planning when K+ < 2.0 mmol/L with respiratory symptoms
Ascending paralysis
▶
Proximal limb weakness progressing to trunk and respiratory muscles
Immediate IV replacement regardless of GI tolerance
ICU-level monitoring required
Hemodynamic goals and monitoring
Cardiac monitoring targets
▶
Continuous cardiac telemetry for K+ < 3.0 mmol/L
12-lead ECG on all confirmed hypokalemia patients
QTc threshold for urgent treatment: QTc > 500 ms
Repeat ECG after every 20 mEq IV KCl in symptomatic patients
IV access and fluid strategy
▶
Peripheral IV adequate for rates up to 10 mEq/hour
Central venous access required for rates > 20 mEq/hour
Glucose-free IV fluids only — dextrose drives K+ intracellularly
Normal saline preferred carrier for IV KCl
Escalation triggers
Escalate to resuscitation bay or ICU for
▶
K+ < 2.0 mmol/L with any symptom
ECG changes: PVCs, VT, QTc prolongation > 500 ms
Digoxin use concurrent with hypokalemia of any degree
Respiratory muscle weakness or ascending paralysis
Refractory hypokalemia after 80 mEq replacement
Concurrent electrolyte targets
▶
Serum magnesium target > 0.8 mmol/L before expecting K+ correction
Serum phosphate check if refeeding syndrome suspected
Calcium check if concurrent alkalosis present
Key decision points
Oral versus IV replacement decision
▶
IV required if K+ < 2.5 mmol/L, ECG changes, vomiting, paralysis
Oral preferred if K+ 2.5-3.5 mmol/L, asymptomatic, tolerating PO
Combined oral and IV acceptable for moderate hypokalemia with mild symptoms
Etiology-directed management
▶
Renal losses: reduce diuretic dose or add potassium-sparing agent
GI losses: antiemetics and antidiarrheals to stop ongoing losses
Transcellular shift: treat underlying cause (thyrotoxicosis, beta-agonist excess)
History
Presenting symptoms
Classic symptom complex
▶
Muscle weakness (proximal > distal)
Muscle cramps and myalgias
Palpitations or irregular heartbeat
Fatigue and malaise
Constipation or abdominal distension
Paresthesias (perioral or extremity tingling)
Severe or alarming symptoms
▶
Ascending limb weakness or inability to walk
Dyspnea or shallow breathing
Syncope or presyncope
Chest pain with palpitations
Medication review
Causative medications
▶
Thiazide diuretics: 11-fold increased risk; average K+ decrease ~0.6 mmol/L
Loop diuretics: average K+ decrease ~0.3 mmol/L; dose-dependent
Laxatives (chronic use)
Corticosteroids (systemic)
Beta-agonists (albuterol, salmeterol)
Insulin (acute transcellular shift)
Amphotericin B (renal tubular toxicity)
Aminoglycosides (renal wasting)
Cisplatin (renal wasting)
Potentiating medications
▶
Digoxin: does not cause hypokalemia but greatly increases toxicity
QT-prolonging medications: risk of torsades de pointes when combined with hypokalemia
Precipitating events and GI losses
Recent illness with GI losses
▶
Vomiting: frequency, volume, duration
Diarrhea: acute infectious vs. chronic
NG suction or colonoscopy preparation
Villous adenoma history
Dietary and intake changes
▶
Decreased oral intake or NPO status
Recent hospitalization with K+-free IV fluids
Alcohol use and malnutrition
Risk factors and exposures
High-risk patient profiles
▶
Heart failure on diuretics
Cirrhosis (hepatic encephalopathy risk with hypokalemia)
Chronic kidney disease (complicates replacement strategy)
Diabetes mellitus (DKA, insulin shifts)
Thyroid disease (thyrotoxic periodic paralysis)
Behavioral and social risk factors
▶
Eating disorder behaviors (purging, laxative abuse in bulimia nervosa)
Excessive licorice consumption (glycyrrhizin mimics mineralocorticoid excess)
Alcoholism and malnutrition
Female sex and Black race: higher diuretic-induced hypokalemia risk
Family history
Hereditary potassium disorders
▶
Familial hypokalemic periodic paralysis
Bartter syndrome (salt-wasting nephropathy with hypokalemia)
Gitelman syndrome (thiazide-like defect)
Liddle syndrome (gain-of-function ENaC mutation)
Familial hyperaldosteronism
Physical Exam
Vital signs and general
Hemodynamic assessment
▶
Heart rate: tachycardia from arrhythmia or volume depletion
Blood pressure: hypotension if volume depleted; hypertension if hyperaldosteronism
Respiratory rate: shallow or labored breathing indicates muscle weakness
Oxygen saturation on room air
General appearance
▶
Cushingoid features (moon facies, central obesity, striae) suggesting cortisol excess
Signs of dehydration (dry mucosa, poor skin turgor)
Neurologic and musculoskeletal exam
Muscle strength assessment
▶
Proximal muscle groups: hip flexors (cannot rise from chair), deltoids
Distal muscle groups: hand grip, dorsiflexion
Ascending pattern: lower limbs before upper limbs in severe cases
Deep tendon reflexes
▶
Hyporeflexia or areflexia in moderate to severe hypokalemia
Decreased muscle tone
Respiratory muscle function
▶
Accessory muscle use
Paradoxical abdominal movement (diaphragmatic weakness)
Cardiac exam
Rhythm assessment
▶
Irregular pulse suggesting arrhythmia
New murmur evaluation
ECG-correlated findings
▶
Bradycardia from AV block in severe cases
Palpable irregular pulse from PVCs
Abdominal exam
Ileus signs
▶
Abdominal distension
Decreased or absent bowel sounds
Tympany to percussion
PITFALLS
Common missed findings
▶
Normal neurological exam does not exclude severe hypokalemia
Rapid-onset hypokalemia more symptomatic than chronic even at milder levels
Serum K+ 3.0 mmol/L may represent > 400 mEq total body deficit
Concurrent hypomagnesemia present in 40-60% — check Mg routinely
Differential Diagnosis
Transcellular redistribution (not true depletion)
Alkalosis-driven shift
▶
Metabolic alkalosis (every 0.1 unit pH rise lowers K+ ~0.5 mmol/L)
Respiratory alkalosis
ICD-10 E87.3 (alkalosis)
Hormone and drug-mediated shift
▶
Insulin administration
Beta-2 agonist excess (albuterol nebulization)
Thyrotoxic periodic paralysis: episodic weakness + low K+ + hyperthyroidism
Refeeding syndrome (phosphate, K+, Mg shift intracellularly)
Pseudohypokalemia
▶
Delayed sample processing with WBC > 100,000/mm3
Repeat with prompt processing on ice
Renal potassium losses
Mineralocorticoid excess
▶
Primary hyperaldosteronism (Conn syndrome): hypertension + hypokalemia; ICD-10 E26.0
Cushing syndrome: elevated cortisol with mineralocorticoid activity; ICD-10 E24
Licorice or fludrocortisone use (apparent mineralocorticoid excess)
Tubular disorders
▶
Renal tubular acidosis type 1 (distal): hypokalemia + non-anion gap acidosis; ICD-10 N25.89
Bartter syndrome: salt wasting, hypokalemia, alkalosis, normal blood pressure; ICD-10 Q87.89
Gitelman syndrome: like Bartter but milder, hypomagnesemia, hypocalciuria; ICD-10 Q87.89
Diuretic effect
▶
Thiazides and loops: most common etiology in ED
Osmotic diuresis from DKA or hyperglycemia
Gastrointestinal losses
Upper GI losses
▶
Vomiting: metabolic alkalosis drives renal K+ wasting (urine Cl < 10 mEq/L)
NG suction
Bulimia nervosa
Lower GI losses
▶
Diarrhea: secretory > osmotic; villous adenoma
Laxative abuse
ICD-10 E87.6 (hypokalemia)
Cannot-miss diagnoses
Diabetic ketoacidosis
▶
Total body K+ depletion masked by initial normokalemia or hyperkalemia from acidosis
K+ drops rapidly with insulin therapy
Anticipate and replace before K+ falls below 3.5 mmol/L during DKA treatment
Adrenal crisis
▶
May present with electrolyte dysregulation
Hypomagnesemia as co-diagnosis
▶
Refractory hypokalemia without Mg correction; check in all cases
Laboratory Tests
Serum electrolytes
Potassium confirmation
▶
Serum K+ < 3.5 mmol/L confirms diagnosis (ICD-10 E87.6)
Severity: mild 3.0-3.5, moderate 2.5-2.9, severe < 2.5 mmol/L
Repeat sample if unexpected result (pseudohypokalemia consideration)
1 mmol/L drop in serum K+ represents 200-400 mEq total body deficit
Basic metabolic panel
▶
Sodium, chloride, bicarbonate for acid-base classification
Metabolic alkalosis common with vomiting or diuretics
BUN and creatinine for renal function assessment
Glucose for DKA screening
Magnesium
▶
Hypomagnesemia present in 40-60% of hypokalemic patients
Concurrent Mg < 0.7 mmol/L makes hypokalemia refractory to replacement
Correct magnesium before or simultaneously with potassium
Phosphate and calcium
▶
Phosphate: low in refeeding syndrome
Calcium: hypercalcemia can accompany hyperaldosteronism
Urine electrolytes
Spot urine potassium
▶
Urine K+ > 15-30 mEq/day indicates renal wasting
Urine K+-to-creatinine ratio > 13 mEq/g suggests renal losses
Urine chloride
▶
Low urine Cl < 10 mEq/L indicates GI or prior diuretic use (vomiting)
High urine Cl > 20 mEq/L suggests active diuretic effect or mineralocorticoid excess
24-hour urine potassium
▶
> 15-30 mEq/day: renal losses
< 15 mEq/day: extrarenal losses (GI, inadequate intake)
Hormonal and specialized tests
Aldosterone and renin
▶
Aldosterone-to-renin ratio for primary hyperaldosteronism screening
Indicated when hypokalemia + hypertension without diuretic use
Elevated aldosterone with suppressed renin: Conn syndrome
TSH
▶
Thyrotoxicosis screen in periodic paralysis presentation
Free T4 and T3 if TSH suppressed
Cortisol
▶
Morning cortisol if Cushing syndrome suspected (central obesity, striae, HTN)
Markers of severity and complications
Creatine kinase
▶
Rhabdomyolysis screen when K+ < 2.0 mmol/L or muscle tenderness
CK > 1000 U/L warrants aggressive IV hydration
Arterial or venous blood gas
▶
Metabolic alkalosis: vomiting, diuretics (pH > 7.45, HCO3 > 26 mmol/L)
Normal anion gap metabolic acidosis with hypokalemia: renal tubular acidosis
Point-of-care iSTAT or blood gas for rapid K+ in ED
Complete blood count
▶
Leukocytosis > 100,000/mm3 raises pseudohypokalemia concern
Diagnostic Tests
Scoring Systems
Severity classification system
▶
Mild hypokalemia: K+ 3.0-3.5 mmol/L
▶
Usually asymptomatic
Outpatient oral replacement appropriate in most cases
Moderate hypokalemia: K+ 2.5-2.9 mmol/L
▶
May have fatigue, cramps, mild weakness
Oral replacement if no severe features; IV if symptomatic
Severe hypokalemia: K+ < 2.5 mmol/L
▶
Approximately 50% symptomatic
High risk for arrhythmia, paralysis, respiratory failure
IV replacement and cardiac monitoring required
ECG risk stratification
▶
No ECG changes: lower urgency but still monitor
U waves or T flattening: moderate urgency, oral or slow IV
ST depression or QTc prolongation: high urgency, IV replacement
QTc > 500 ms or arrhythmia: emergent IV replacement with telemetry
Scoring Systems — Transtubular Potassium Gradient
TTKG (transtubular potassium gradient) — historical tool
▶
TTKG = (urine K+ / serum K+) divided by (urine osmolality / serum osmolality)
TTKG > 4 suggests renal potassium wasting
TTKG < 2 suggests extrarenal cause
Now considered less reliable; urine K/creatinine ratio preferred
MRI
MRI in hypokalemia workup
▶
Not routinely indicated for hypokalemia diagnosis or management
MRI adrenals for suspected adrenal adenoma (Conn syndrome) if CT adrenals inconclusive
▶
Characterization of adrenal lesions > 1 cm
Differentiation of adenoma from hyperplasia
MRI brain if central neurologic cause suspected (hypothalamic or pituitary lesion causing cortisol excess)
▶
Pituitary adenoma evaluation in Cushing disease
MRI spine if ascending paralysis requires cord lesion exclusion
▶
Differentiate hypokalemic paralysis from spinal cord compression
CT
CT adrenals
▶
Indicated when aldosterone-to-renin ratio elevated (primary hyperaldosteronism confirmed)
Sensitivity ~70% for adrenal adenoma > 1 cm
Protocol: adrenal-protocol CT with pre- and post-contrast phases
Adrenal vein sampling required if CT is inconclusive before surgery
CT abdomen and pelvis
▶
Ileus evaluation: dilated loops of bowel, air-fluid levels
Suspected villous adenoma or secretory diarrhea source
CT chest
▶
Respiratory compromise: aspiration, pneumonia, effusion
Not routine in hypokalemia workup
Ultrasound
Renal ultrasound
▶
Suspected renal tubular acidosis or chronic renal potassium wasting
Nephrocalcinosis: seen in distal RTA
Renal size and echogenicity: CKD evaluation
Cardiac point-of-care ultrasound
▶
Pericardial effusion if significant ECG changes present
Left ventricular function in heart failure patients
Volume status assessment: IVC collapsibility
Abdominal ultrasound
▶
Adrenal mass if CT not immediately available
Ascites in cirrhotic patients
Disposition
ICU admission indications
ICU or step-down required for
▶
K+ < 2.0 mmol/L regardless of symptoms
Ventricular arrhythmia (VT, VF, torsades de pointes)
Ascending paralysis or respiratory muscle compromise
Concurrent digoxin toxicity
Need for IV replacement > 20 mEq/hour (central access required)
Rhabdomyolysis with renal injury
Telemetry admission indications
Telemetry ward appropriate for
▶
K+ 2.0-2.5 mmol/L with ECG changes
Active cardiac disease (MI, heart failure, LV hypertrophy) with any hypokalemia
Concurrent QT-prolonging medications
Ongoing GI losses requiring IV replacement
Refractory hypokalemia (failure to correct with 60 mEq replacement)
Cirrhosis with hepatic encephalopathy risk
Observation or ED extended care
Observation appropriate for
▶
K+ 2.5-3.0 mmol/L without severe features
IV or oral replacement in progress with reassessment planned
Repeat K+ after 2-4 hours to confirm correction
Discharge if K+ improves, symptoms resolve, cause identified
Discharge criteria
Copy
Safe for discharge when
▶
K+ 3.0-3.5 mmol/L (mild), asymptomatic, no ECG changes
Clear etiology identified (e.g., diuretic-related)
Oral KCl prescription provided
Reliable follow-up arranged within 1-3 days for recheck
No concerning comorbidities (no digoxin, no active cardiac disease)
Specialist consultation triggers
Nephrology
▶
Unexplained renal potassium wasting
Suspected Bartter or Gitelman syndrome
Renal tubular acidosis workup
Endocrinology
▶
Suspected primary hyperaldosteronism
Cushing syndrome workup
Thyrotoxic periodic paralysis management
Cardiology
▶
Refractory ventricular arrhythmia with hypokalemia
Digoxin toxicity management
Treatment
IV potassium replacement — emergency and severe
Cardiac arrest or malignant arrhythmia from hypokalemia
▶
IV KCl 5-10 mEq IV push over 15-30 minutes with continuous cardiac monitoring
▶
Repeat bolus until arrhythmia suppressed and K+ > 3.0 mmol/L
Followed by maintenance infusion
Severe hypokalemia (K+ < 2.5 mmol/L) with symptoms
▶
IV KCl 20-40 mEq in 100 mL normal saline over 2-4 hours
▶
Maximum safe peripheral rate: 10 mEq/hour
Rate up to 20 mEq/hour acceptable with continuous telemetry
Rates > 20 mEq/hour require central venous access
Glucose-free IV fluids only
Check serum K+ every 2-4 hours during IV replacement
Maximum replacement: up to 200-400 mEq/day in severe cases under monitoring
Oral potassium replacement — moderate and mild
Oral KCl (preferred formulation)
▶
Dose: 40-100 mEq/day in 2-5 divided doses
▶
Maximum per dose: 40 mEq
Maximum per day: 200 mEq
Take with food to minimize GI irritation
Rule of thumb: 20 mEq oral KCl raises serum K+ by ~0.2 mmol/L
KCl superior to other formulations: up to 40% better absorption
Alternative formulations
▶
Potassium bicarbonate or citrate: preferred in metabolic acidosis (RTA)
Potassium phosphate: concurrent hypophosphatemia (refeeding syndrome)
Contraindications
▶
Concurrent triamterene or amiloride: contraindicated with KCl
Caution with ACE inhibitors, ARBs, spironolactone, NSAIDs (rebound hyperkalemia risk)
Magnesium replacement
Concurrent hypomagnesemia treatment
▶
IV magnesium sulfate 1-2 g IV over 15-30 minutes
▶
Dilute in 50-100 mL normal saline
Repeat up to 4-6 g/day if Mg remains low
Hypokalemia will be refractory without magnesium correction
Oral magnesium oxide 400 mg daily for maintenance if mild deficiency
▶
GI side effects (diarrhea) limit dose titration
Recheck Mg and K+ together after 2-4 hours
Addressing underlying cause
Diuretic-related hypokalemia
▶
Reduce diuretic dose if clinically feasible
Add potassium-sparing diuretic (spironolactone, eplerenone, amiloride)
▶
Spironolactone 25-50 mg daily for heart failure with diuretic-induced hypokalemia
Chronic prophylaxis: KCl 20 mEq daily for patients on chronic diuretics
GI loss treatment
▶
Ondansetron 4-8 mg IV for vomiting cessation
Loperamide 4 mg then 2 mg per loose stool (max 16 mg/day) for diarrhea
DKA management
▶
Hold insulin until K+ > 3.5 mmol/L
▶
Add KCl 20-40 mEq/L to IV fluids if K+ 3.0-3.5 mmol/L
Add KCl 40-60 mEq/L to IV fluids if K+ < 3.0 mmol/L
Recheck K+ every 2 hours during DKA insulin infusion
Heart failure patients
▶
Optimize ACE inhibitor or ARB dose first
Add mineralocorticoid receptor antagonist (spironolactone or eplerenone)
Target K+ > 4.0 mmol/L in HF patients (even mild hypokalemia increases arrhythmia risk)
Monitoring during treatment
Serum potassium monitoring intervals
▶
During IV replacement: every 2-4 hours
Stable oral replacement: recheck at 24-48 hours
Chronic supplementation: every 1-3 months
Cardiac monitoring during IV replacement
▶
Continuous telemetry for K+ < 2.5 mmol/L or ECG changes
ECG repeat after each 40 mEq IV replacement in high-risk patients
Potassium overcorrection risk
▶
Stop IV replacement when K+ > 4.0 mmol/L
Rebound hyperkalemia risk if concurrent RAAS blockade
Special Populations
Pregnancy
Physiologic changes affecting potassium
▶
Plasma volume expansion dilutes serum K+
Elevated aldosterone in normal pregnancy promotes renal K+ wasting
Progesterone partially antagonizes aldosterone, limiting net loss
Causes specific to pregnancy
▶
Hyperemesis gravidarum: severe vomiting causing significant GI and renal losses
▶
K+ can fall below 2.5 mmol/L in severe cases
IV hydration with KCl required
Pre-eclampsia treatment: magnesium sulfate may mask neurologic signs of hypokalemia
Treatment in pregnancy
▶
Oral KCl preferred for mild-moderate hypokalemia (safe throughout pregnancy)
IV KCl for severe or symptomatic hypokalemia
▶
Same dosing as non-pregnant adults
Fetal cardiac monitoring for K+ < 2.5 mmol/L with IV replacement
Diuretic use in pregnancy: thiazides generally avoided; loop diuretics restricted
Potassium-sparing diuretics: limited safety data in pregnancy
Geriatric
Heightened risk profile
▶
Polypharmacy: multiple diuretics, laxatives, corticosteroids common
Decreased renal concentrating ability limits compensation
Decreased muscle mass reduces total body potassium reserve
Higher prevalence of underlying cardiac disease (lower arrhythmia threshold)
Atypical presentations
▶
Weakness misattributed to deconditioning or sarcopenia
Falls from proximal muscle weakness
Confusion or delirium as presenting feature
Constipation and ileus more pronounced
Management modifications
▶
Lower threshold for ECG and telemetry monitoring
Caution with rapid IV replacement due to reduced cardiac reserve
Oral route preferred when tolerated to avoid fluid overload
Renal function impacts potassium excretion: reduced dose in CKD stage 3+
Monthly potassium checks recommended for all geriatric patients on diuretics
Pediatrics
Normal potassium ranges by age
▶
Neonates: 3.5-5.5 mmol/L
Infants and children: 3.5-5.0 mmol/L
Adolescents: 3.5-4.5 mmol/L (adult range)
Common pediatric causes
▶
Gastroenteritis with diarrhea and vomiting: most common in infants
Familial hypokalemic periodic paralysis: autosomal dominant, presents in adolescence
Bartter syndrome: presents in infancy with failure to thrive, polyuria, hypokalemia
Gitelman syndrome: milder, presents in older children or adolescents
Refeeding syndrome in malnourished children
Weight-based dosing
▶
Oral KCl: 1-3 mEq/kg/day in divided doses (max 40 mEq per dose)
IV KCl: 0.5-1 mEq/kg over 1-2 hours (maximum 1 mEq/kg/hour)
▶
Maximum single infusion rate: 0.5 mEq/kg/hour for peripheral access
Cardiac monitoring required during IV infusion
Magnesium: 25-50 mg/kg IV over 30 minutes if concurrent hypomagnesemia
Special considerations
▶
Infants tolerate liquid KCl preparations
DKA is the most common emergency cause requiring careful K+ monitoring
Thyrotoxic periodic paralysis rare before adolescence
Background
Epidemiology
Prevalence and incidence
▶
Most common electrolyte abnormality in the emergency department
ED prevalence approximately 5.5%
General hospitalized patients: 20% have K+ < 3.5 mmol/L at some point
Community prevalence: ~2-3% of general population
Mortality and morbidity
▶
K+ < 3.0 mmol/L associated with increased all-cause mortality (adjusted HR 1.49)
Ventricular arrhythmias are the leading cause of hypokalemia-related death
In heart failure: even K+ 3.5-4.0 mmol/L increases ventricular arrhythmia risk
ECG abnormalities present in ~40% of hypokalemic ED patients
▶
T-wave flattening: 27%
ST depression: 16%
QTc prolongation: 14%
High-risk populations
▶
Heart failure on diuretics
Cirrhosis with secondary hyperaldosteronism
Patients on digoxin (narrow therapeutic index)
Patients receiving chemotherapy (cisplatin, amphotericin)
Pathophysiology
Normal potassium homeostasis
▶
98% of total body K+ is intracellular (primarily muscle and liver)
Normal total body K+: 3,000-4,000 mEq
Serum K+ reflects extracellular fraction and is tightly regulated 3.5-5.0 mmol/L
Mechanisms of hypokalemia
▶
Transcellular shift into cells
▶
Alkalosis: each 0.1 pH unit rise shifts K+ down ~0.5 mmol/L
Insulin activation of Na-K-ATPase
Beta-2 adrenergic stimulation (catecholamine surge, albuterol)
Thyrotoxic excess: TSH-stimulated Na-K-ATPase activity
Renal potassium wasting
▶
Aldosterone activates principal cell ENaC and K+ channels in collecting duct
Diuretics block upstream Na+ reabsorption, increasing distal delivery and K+ secretion
High urine flow rate (osmotic diuresis) washes out K+
RTA type 1: failure of H+ secretion impairs K+ reabsorption
GI potassium losses
▶
Vomiting causes metabolic alkalosis, which drives renal K+ wasting (urine Cl < 10 mEq/L is key clue)
Diarrhea: direct colonic K+ loss (stool K+ 70-90 mEq/L in secretory diarrhea)
Cardiac electrophysiology effects
▶
Hyperpolarizes resting membrane potential
Prolonged phase 3 repolarization increases arrhythmia susceptibility
U waves represent delayed Purkinje fiber repolarization
Torsades de pointes: polymorphic VT triggered by prolonged QTc from hypokalemia
Neuromuscular effects
▶
Reduced resting membrane potential impairs action potential generation
Proximal muscle weakness before distal (higher metabolic demand)
Smooth muscle: ileus from decreased gut peristalsis
Therapeutic Considerations
Potassium replacement rationale
▶
Target K+ > 3.5 mmol/L for most patients
Target K+ > 4.0 mmol/L for heart failure, active ischemia, or digoxin use
KCl is preferred salt: corrects concurrent hypochloremia and metabolic alkalosis
Potassium bicarbonate preferred in metabolic acidosis with hypokalemia (RTA)
Magnesium dependency
▶
Mg is required cofactor for Na-K-ATPase activity
Low Mg impairs K+ reabsorption in loop of Henle
Hypokalemia will not correct without simultaneous Mg repletion
Class I recommendation: check and correct Mg in all hypokalemic patients
Diuretic pharmacology
▶
Thiazide effect: blocks NaCl cotransporter in distal tubule, increasing K+ secretion
▶
11-fold higher risk of hypokalemia vs non-use
Average K+ decrease: ~0.6 mmol/L
Loop diuretic effect: blocks NKCC2 in thick ascending limb
▶
Average K+ decrease: ~0.3 mmol/L; dose-dependent in heart failure
Potassium-sparing diuretics: spironolactone blocks aldosterone; amiloride blocks ENaC
Evidence levels
▶
Correction of hypomagnesemia before K+ replacement: Class I recommendation
IV replacement for K+ < 2.5 mmol/L or ECG changes: Class I recommendation
Avoid glucose-containing IV fluids during K+ replacement: ACEP Level B recommendation
Target K+ > 4.0 mmol/L in heart failure patients: Class IIa recommendation (JACC)
Patient Discharge Instructions
copy discharge instructions
Copy
What is hypokalemia
▶
Low potassium level in your blood
Potassium is essential for your heart, muscles, and nerves to work properly
Your potassium level today and what it means
▶
Mild (3.0-3.5 mmol/L): usually manageable with diet and medication changes
Moderate (2.5-2.9 mmol/L): requires oral potassium supplements
You were treated in the emergency department and your level improved
Take your potassium supplement exactly as prescribed
▶
Take with food or a full glass of water to avoid stomach upset
Do not crush or chew extended-release tablets
Do not take more than the prescribed dose
Eat potassium-rich foods
▶
Bananas, oranges, avocados, tomatoes, spinach, potatoes
Beans, dairy products, nuts, and seeds
Reduce salt intake: high sodium promotes potassium loss from kidneys
Take all medications as prescribed
▶
If your doctor changed your diuretic (water pill) dose, follow the new instructions
Do not stop any heart or blood pressure medications without asking your doctor first
Avoid these until your potassium is normal
▶
Excessive laxative use
Heavy alcohol intake
Sports drinks or other drinks that are high in sugar (promote potassium shifts)
Your follow-up appointment
▶
Blood test to recheck potassium within 1-3 days (moderate) or within 1 week (mild)
See your family doctor or specialist to determine the cause
Return to the emergency department immediately if you experience
▶
Palpitations, rapid heartbeat, or irregular heartbeat
Chest pain
Severe muscle weakness or inability to walk
Difficulty breathing or shortness of breath
Fainting or near-fainting
Persistent vomiting or diarrhea preventing you from taking your medication
References
Guidelines and key sources
Kim MJ, Valerio C, Knobloch GK
▶
Potassium Disorders: Hypokalemia and Hyperkalemia
American Family Physician 2023
PMID 36689973
Kildegaard H, Brabrand M, Forberg JL, et al
▶
Prevalence and Prognostic Value of Electrocardiographic Abnormalities in Hypokalemia: A Multicenter Cohort Study
Journal of Internal Medicine 2024
PMID 38098171
Gennari FJ
▶
Hypokalemia
New England Journal of Medicine 1998
NEJM 339:451-458
Ferreira JP, Butler J, Rossignol P, et al
▶
Abnormalities of Potassium in Heart Failure: JACC State-of-the-Art Review
Journal of the American College of Cardiology 2020
PMID 32498812
Lin Z, Wong LYF, Cheung BMY
▶
Diuretic-Induced Hypokalaemia: An Updated Review
Postgraduate Medical Journal 2022
PMID 33688065
Oswald S, Ravioli S, Schwarz C, Lindner G
▶
Hypokalaemia in the Emergency Department: Aetiology, Diagnosis, and Management
Swiss Medical Weekly 2026
PMID 41962024
Sandau KE, Funk M, Auerbach A, et al
▶
Update to Practice Standards for Electrocardiographic Monitoring in Hospital Settings
American Heart Association Scientific Statement, Circulation 2017
Helfant RH
▶
Hypokalemia and Arrhythmias
American Journal of Medicine 1986
PMID 3706349
Viera AJ, Wouk N
▶
Potassium Disorders: Hypokalemia and Hyperkalemia
American Family Physician 2015
PMID 26371733
ICD-10 coding
Hypokalemia
▶
ICD-10 E87.6 (hypokalemia)
ICD-10 E26.0 (primary hyperaldosteronism — Conn syndrome)
ICD-10 E24 (Cushing syndrome)
ICD-10 N25.89 (renal tubular acidosis)
ICD-10 E87.3 (alkalosis as precipitant)
ICD-10 Q87.89 (Bartter or Gitelman syndrome)
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.
← Management Protocols
Home
Management Protocols
Hypokalemia