Alkalosis
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Introduction
The Case of...
a simple case introducing clincial presentation and calling for a differential diagnosis to get students thinking.
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+ lossGI: vomiting, NG suction aldosterone-mediated renal loss
hypokalemia |
HCO3- gainadministration IV/PO, citrate (transfusion), acetate (TPN) |
decreased HCO3- loss |
Respiratory Alkalosis
Respiratory alkalosis occurs with hyperventilation.
Pathophysiology
Signs and Symptoms
- history
- physical exam
History
Alkalosis can cause neurological symptoms
Physical Exam
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
blood tests
- CBCD
- lytes
- BUN and creatinine
- serum osmolality
- serum aldosterone and renin
urine tests
- urinalysis
- urine electrolytes
- osmolality
Diagnostic Imaging
Not normally indicated.
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
Consequences and Course
Resources and References
Topic Development
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