Metabolic alkalosis is seen in?

Appeared in: DSSSB - 29 August 2019 (Shift-2)

Explanation

Metabolic alkalosis is an acid-base imbalance characterized by an elevated blood pH (>7.45) and an increased bicarbonate (HCO₃⁻) concentration (>26 mEq/L).
Excessive intake of alkaline drugs, such as sodium bicarbonate-containing antacids, directly adds base to the extracellular fluid.
This influx of alkali overwhelms the body's buffering capacity, leading to a primary increase in plasma HCO₃⁻ and resulting in metabolic alkalosis.
The body attempts to compensate by decreasing the respiratory rate (hypoventilation) to retain CO₂, but this is often insufficient.

Option A: Diabetic ketoacidosis (DKA) is a classic cause of metabolic acidosis, not alkalosis. The lack of insulin leads to the production of acidic ketone bodies.
Option B: Renal failure leads to metabolic acidosis because the failing kidneys cannot excrete the daily load of metabolic acids or regenerate bicarbonate.
Option D: Diarrhea causes metabolic acidosis due to the significant loss of bicarbonate-rich fluids from the lower gastrointestinal tract.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Causes of Metabolic Alkalosis as background academic context rather than a clinical decision trigger.
Nurses must assess for metabolic alkalosis in at-risk patients, such as those with prolonged vomiting, nasogastric suction, or those taking loop/thiazide diuretics.
Patient education is crucial. Advise patients on the appropriate use of over-the-counter antacids to prevent overuse and subsequent metabolic alkalosis.
Monitoring is key: Nurses should closely watch arterial blood gases (ABGs) and serum electrolytes, particularly potassium, as hypokalemia often accompanies metabolic alkalosis.

How to Approach the Question

First, identify the core concept in the question stem: 'Metabolic alkalosis'.
Recall the definition of metabolic alkalosis: a condition of increased bicarbonate (base) or decreased acid in the body.
Evaluate each option to see if it leads to a gain of base or a loss of acid.
Option A (DKA): Causes acid gain (ketones). Incorrect.
Option B (Renal failure): Causes acid retention. Incorrect.
Option C (Excess antacids): Causes base gain (alkali). Correct.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 2B p. 77-79

E6 Medicine Davidson Principles Practice 24e p. 386-388

Practise the full DSSSB - 29 August 2019 (Shift-2)

Attempt every question from this paper in a timed mock, then review the full solution for each one.