Rosen & Barkin's 5-Minute Emergency Medicine Consult (381 page)

FOLLOW-UP

• Need of IV potassium repletion
  
• Cardiac dysrhythmias
  
• Profound muscle weakness
  
• Ongoing K losses
  
• Serum potassium <2.5 mEq/L
  
• Associated with significant hypotension or severe HTN
  
• Significant comorbidities or geriatric
  

• Asymptomatic
  
• Able to replete deficiency with oral potassium
  
• Early follow-up available and reliable patient
  
• Repeat electrolyte determination in 2–3 days with the primary care doctor.
  
• Nephrology referral or consult if suspicion of renal wasting.
  
• Continue K replacement for 2–3 days if acute, self-limited loss, but ongoing therapy if the cause is not corrected (e.g., diuretic therapy, chronic diarrhea).
  

• If hypokalemia is accompanied by acidosis, correct hypokalemia 1st before treating the acidosis so as to avoid life-threatening hypokalemia from transcellular shifts.
  
• Minimize glucose administration when treating hypokalemia, since glucose will stimulate insulin release, which will lead to K movement into cells.
  
• Large doses of oral potassium can be given safely in patients with normal renal function, limited only by GI tolerance.
  
• Check for hypomagnesemia if hypokalemia is severe or resistant to replacement therapy.
  
• Relatively small amounts of IV potassium are required to reverse hypokalemia in periodic paralysis and states of adrenergic excess since transcellular shifts are transient.
  

• Alkaabi JM, Mushtaq A, Al-Maskari FN, et al. Hypokalemic periodic paralysis: A case series, review of the literature and update of management.
  Eur J Emerg Med.
  2010;17(1):45–47.
  
• Ben Salem C, Himouda H, Bouraoui K. Drug-induced hypokalaemia.
  Curr Drug Saf.
  2009;4(1):55–61.
  
• Grenniee M, Wingo CS, McDonough AA, et al. Narrative review: Evolving concepts in potassium homeostasis and hypokalemia.
  Ann Intern Med
  . 2009;150:619–625.
  
• Palmer BF. A physiologic based approach to the evaluation of a patient with hypokalemia.
  Am J Kidney Dis.
  2010;56(6):1184–1190.
  
• Pepin J, Shields C. Advances in diagnosis and management of hypokalemic and hyperkalemic emergencies.
  Emerg Med Pract.
  2012;14(2):1–18.
  
• Philips DA, Bauch TD. Rapid correction of hypokalemia in a patient with an implantable cardioverter-defibrillator and recurrent ventricular tachycardia.
  J Emerg Med.
  2010;38(3):308–316.
  
• Schaefer TJ, Wolford RW. Disorders of potassium.
  Emerg Med Clin North Am
  . 2005;23(3):723–747.
  

See Also (Topic, Algorithm, Electronic Media Element)

Hyperkalemia

CODES

• 255.13 Bartter’s syndrome
  
• 276.3 Alkalosis
  
• 276.8 Hypopotassemia
  

BASICS

• Sodium <136 mEq/L
  
• Most common electrolyte disturbance (1–4% of hospitalized patients)
  

• Low measured serum sodium but normal measured serum osmolarity
  
• Occurs secondary to the displacement of sodium to aqueous phase of serum
  
• Seen with elevated lipids or proteins
  
• Lab or blood raw error
  
• Disease examples include:
  
  • Multiple myeloma
    
  • Hyperlipidemia
    

• Inappropriate retention of water
  
• Disease examples include:
  
  • CHF
    
  • Cirrhosis
    
  • Renal failure
    
  • Nephrotic syndrome
    

• Patients tend to have increased total body water without marked edema
  
• Purest form of dilutional hyponatremia
  
• Disease examples include:
  
  • Endocrine abnormalities:
    
    • Hypothyroid
      
    • Stress
      
    • Syndrome of inappropriate antidiuretic hormone (SIADH)
      
  • Diseases that cause SIADH:
    
    • Pulmonary disease (tuberculosis, Legionella, Aspergillosis, COPD)
      
    • CNS disorders (malignancy, sarcoid, infection)
      
    • Cancer (small cell lung, pancreas, duodenum)
      
    • HIV infection
      
  • Water intoxication (3–7% of institutionalized psychotic patients), can also occur in marathon runners
    
  • Mineralocorticoid abnormalities
    
  • Postoperative hyponatremia (particularly after transurethral prostatectomy)
    
  • Consumption of large amounts of beer (beer potomania)
    
  • MDMA (Ecstasy)
    

• Deficits in total body water and total body sodium
  
• Sodium deficits exceed water deficits
  
• Possible etiologies include:
  
  • GI losses
    
  • Sweating
    
  • Cerebral salt wasting (occurs after head injury or neurosurgical procedures)
    
  • Burns
    
  • Cystic fibrosis
    
  • Salt-wasting nephropathies
    
  • Diuretics
    

• Drugs may stimulate antidiuretic hormone (ADH) and cause hyponatremia:
  
  • Amiodarone
    
  • Barbiturates
    
  • Bromocriptine
    
  • Carbamazepine
    
  • Clofibrate
    
  • Cyclophosphamide
    
  • Opiates
    
  • Oxytocin
    
  • Vincristine, vinblastine
    
• Drugs may increase sensitivity to ADH and cause hyponatremia:
  
  • Chlorpropamide
    
  • NSAIDs
    
• Drugs may stimulate thirst and cause hyponatremia:
  
  • Amitriptyline
    
  • Ecstasy
    
  • Fluoxetine
    
  • Fluphenazine
    
  • Haloperidol
    
  • Sertraline
    
  • Thiothixene
    

• Due to excessive osmotically active substances
  
• Possible etiologies include:
  
  • Elevated glucose (most common cause of hyponatremia)
    
  • Corrected Na
    ⁺
    = 0.016 × (measured glucose – to 100) + measured sodium
    
  • Mannitol infusion
    
  • Maltose and glycine
    

• More prone to water intoxication
  
• High incidence of iatrogenic hyponatremia due to dilute formula or rehydration with water only
  
• If hyponatremia secondary to DKA, follow hydration per pediatric DKA recommendations
  

Conivaptan and Tolvaptan are class C drugs in pregnancy.

• Tend to develop more symptoms
  
• Hyponatremia more common due to impaired water secretion and low sodium diets
  

DIAGNOSIS

• Mild: Na
  ⁺
  >120 mEq/L:
  
  • Headache
    
  • Nausea
    
  • Vomiting
    
  • Weakness
    
  • Anorexia
    
  • Muscle cramps
    
  • Rhabdomyolysis
    
• Moderate: Na
  ⁺
  between 110 and 120 mEq/L:
  
  • Impaired response to verbal stimuli
    
  • Decreased response to painful stimuli
    
  • Visual/auditory hallucinations
    
  • Bizarre behavior
    
  • Incontinence
    
  • Hyperventilation
    
  • Gait disturbance
    
• Severe: Na
  ⁺
  <110 mEq/L:
  
  • Signs of herniation
    
  • Decorticate/decerebrate posturing
    
  • Bradycardia
    
  • HTN
    
  • Altered temperature regulation
    
  • Dilated pupils
    
  • Seizure activity
    
  • Respiratory arrest
    
  • Coma/unresponsive