Metabolic Alkalosis

 

Causes and Risk Factors

 

  • metabolic
  • respiratory

Metabolic Acidosis

Metabolic alkalosis is most commonly caused by excessive vomiting and loss of acid or excessive injestion of bicarbonate-containing antacids. Maitenance of the increased pH implies a problem with renal bicarbonate excretion.

Diuretics, both loop and thiazides, can also be causative.

 

H+ loss

GI: vomiting, NG suction

aldosterone-mediated renal loss

  • volume depletion
  • diuretics
  • hypomagnesemia
  • skin loss: sweat, burns
  • increased renin: renal artery stenosis, tumour
  • Conn's, Cushing's

hypokalemia

HCO3- gain

administration IV/PO, citrate (transfusion), acetate (TPN)

decreased HCO3- loss

Respiratory Alkalosis

Respiratory alkalosis occurs with hyperventilation.

 

 

Signs, Symptoms, and Diagnosis

 

  • history
  • physical exam
  • lab investigations

History

Physical Exam

 

Alkalosis can cause neurological symptoms

Lab Investigations

arterial blood gases

blood tests

  • CBCD
  • lytes
  • BUN and creatinine
  • serum osmolality
  • serum aldosterone and renin

urine tests

  • urinalysis
  • urine electrolytes
  • osmolality

 

return to top

 

 

 

Treatments

 

Alkalosis can be partially reversed by breathing into a paper bag (or so the story goes).

 

ABC

oxygen and IV

 

Treat underlying cause

volume sensitive: fluid recuscitation, replentish K and Mg

volume insensitive: spironolactone, amiloride

 

a carbonic anhydrase inhibitor such as acetazolamide can be used to facilitate HCO3 loss in kidney

 

return to top

 

 

 

Consequences and Course

 

 

return to top

 

 

 

Resources and References