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Difficulty: EasyNephrology

Match each clinical presentation with its most likely primary acid-base disorder.

  • 22-year-old with type 1 diabetes, missed insulin doses, and blood glucose of 450 mg/dLHigh anion gap metabolic acidosis
  • 65-year-old with severe chronic obstructive pulmonary disease (COPD) exacerbation and hypoventilationRespiratory acidosis
  • 19-year-old presenting with acute hyperventilation due to a severe panic attackRespiratory alkalosis
  • 45-year-old with intractable vomiting for 3 days due to pyloric stenosisMetabolic alkalosis

Answer

The presentations match as follows: missed insulin doses with High anion gap metabolic acidosis; COPD hypoventilation with Respiratory acidosis; panic attack hyperventilation with Respiratory alkalosis; intractable vomiting with Metabolic alkalosis.
Each clinical scenario describes a classic, straightforward presentation for one of the four primary acid-base disorders. Identifying the fundamental underlying mechanism—such as ketoacid overproduction, carbon dioxide retention, carbon dioxide washout, or direct acid loss—is essential for accurate diagnosis.

Step-by-Step Solution

1
Analyze the patient with type 1 diabetes and severe hyperglycemia.
The clinical picture indicates diabetic ketoacidosis.
This condition is characterized by the production of ketoacids, which are unmeasured anions that consume bicarbonate and widen the anion gap.
2
Analyze the patient with a severe COPD exacerbation and hypoventilation.
The decreased respiratory drive leads to carbon dioxide retention.
Retained carbon dioxide acts directly as an acid in the blood, leading to a primary respiratory acidosis.
3
Analyze the patient with acute hyperventilation from a panic attack.
The rapid breathing causes excessive elimination of carbon dioxide.
Loss of carbon dioxide raises the blood pH, resulting in a primary respiratory alkalosis.
4
Analyze the patient with intractable vomiting.
Vomiting leads to the continuous loss of gastric contents.
Gastric fluid is rich in hydrochloric acid. Losing this acid directly increases the serum pH, causing a primary metabolic alkalosis.

Key Concept

Primary Acid-Base Disorders
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Topics

Nephrology

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