Repeated vomiting can produce which of the following biochemical abnormalities?

Appeared in: UPRVUNL - 2021

Explanation

Repeated vomiting causes the loss of gastric fluid, which is rich in hydrochloric acid (HCl).
The loss of hydrogen ions (H⁺) and chloride ions (Cl⁻) from the stomach leads to an increase in the concentration of bicarbonate (HCO₃⁻) in the blood.
This increase in bicarbonate, a base, raises the blood's pH, resulting in a state of metabolic alkalosis.
Volume depletion from vomiting also activates the renin-angiotensin-aldosterone system, which further promotes H⁺ and potassium excretion by the kidneys, maintaining the alkalosis.

Option B: Uremia is a condition involving abnormally high levels of waste products in the blood, which is a hallmark of kidney failure. It is not a direct consequence of vomiting.
Option C: Metabolic acidosis is characterized by a decrease in blood pH and bicarbonate levels. Vomiting causes a loss of acid, leading to the opposite condition, metabolic alkalosis.
Option D: Septicemia, or sepsis, is a life-threatening systemic infection. It is an immunological and infectious process, not a direct biochemical result of fluid and electrolyte loss from vomiting.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Acid-Base Imbalances as background academic context rather than a clinical decision trigger.
Nurses must monitor patients with persistent vomiting for signs of metabolic alkalosis, such as confusion, muscle twitching, or tetany.
Key nursing interventions include administering antiemetics to control vomiting, replacing fluids and electrolytes with IV solutions (often normal saline with potassium), and closely monitoring lab values (pH, electrolytes, bicarbonate).
What if? If the patient had severe diarrhea instead of vomiting, the nurse would anticipate metabolic acidosis due to the loss of bicarbonate-rich intestinal fluid, and the treatment would focus on fluid replacement and correcting the acidosis.

How to Approach the Question

First, identify the key process in the question: 'Repeated vomiting'.
Recall the composition of gastric fluid. It is highly acidic, containing hydrochloric acid (HCl).
Consider the effect of losing large amounts of acid from the body. Losing acid will make the blood more alkaline (basic).
Evaluate the options based on this understanding. 'Metabolic alkalosis' is a state of high blood pH caused by metabolic processes.
Differentiate this from metabolic acidosis (low pH, often from diarrhea), uremia (kidney failure), and septicemia (infection) to confirm the correct answer.

Concept Tested & Keywords

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E6 Nelson Textbook of Pediatrics(2024) — Volume 1 pp. 563-565, 565-567

E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 2 — Subpart A (pp 1-239 of 478) p. 86-88

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