Basic Concepts of Fluid and Electrolyte Therapy

Table 15: Causes of metabolic acidosis (hyperchloraemic) with a normal anion gap
Gastrointestinal HCO 3 – loss
diarrhoea
fistulae
Renal HCO 3 – loss
renal tubular acidosis
acetazolamide
Infusion of 0.9% saline
Metabolic acidosis with a high anion gap - can be caused by four
broad categories of disorders including ketoacidosis, lactic acidosis,
poisonings or advanced acute or chronic kidney disease.
Ketosis occurs when there is a lack of insulin or glucose depletion. To
compensate fatty acids are oxidised to produce energy which results
in the production of ketoacids as a by-product.
Severe diabetic ketoacidosis occurs secondary to insulin deficiency
(Chapter 10)
Ketosis may also occur with prolonged starvation or in alcoholics
Lactic acidosis is subdivided into
Type A lactic acidosis - secondary to insufficient oxygen delivery to
the tissues
hypovolaemic shock
cardiogenic shock
septic shock
Type B lactic acidosis – impaired gluconeogenesis causing inability
to clear lactate
liver failure
metformin
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