Which electrolyte imbalance is most commonly seen in bulimia nervosa?

Appeared in: NORCET 10 Mains

Explanation

Bulimia nervosa is characterized by binge eating followed by purging behaviors like self-induced vomiting or misuse of laxatives and diuretics.
These purging methods lead to a significant loss of potassium from the body, both through gastric fluids (vomiting) and increased renal/bowel excretion (laxatives/diuretics).
The resulting potassium deficit is known as hypokalemia, defined as a serum potassium level below 3.5 mEq/L.
Hypokalemia is the most frequently observed electrolyte disturbance in this patient population and can lead to severe complications, particularly cardiac arrhythmias.

Option A: Hyperkalemia (high potassium) is the opposite of what occurs in bulimia. Purging behaviors cause potassium loss, not retention.
Option C: Hypernatremia (high sodium) is not the most common imbalance. While dehydration from purging can concentrate sodium, significant fluid and sodium loss can also occur, sometimes leading to hyponatremia (low sodium).
Option D: Hypercalcemia (high calcium) is not a typical finding in bulimia nervosa. The condition is not directly linked to calcium regulation.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Electrolyte Imbalances in Bulimia Nervosa as background academic context rather than a clinical decision trigger.
Monitoring for hypokalemia is a critical nursing responsibility for patients with known or suspected bulimia nervosa due to the risk of life-threatening cardiac events.
Nurses should assess for signs of hypokalemia, such as muscle weakness, fatigue, constipation, and palpitations, and monitor ECG for changes like flattened T-waves, U-waves, and ST depression.
Patient education on the dangers of purging and the importance of nutritional rehabilitation is a key component of care.

How to Approach the Question

First, identify the key terms in the question: 'electrolyte imbalance' and 'bulimia nervosa'.
Recall the defining characteristic of bulimia nervosa, which is the cycle of binging and purging.
Consider the common methods of purging: self-induced vomiting and abuse of laxatives/diuretics.
Analyze how these actions would affect electrolytes. Vomiting leads to the loss of stomach acid (HCl) and potassium (K+). Laxatives and diuretics also cause significant potassium loss.
Evaluate the options based on this analysis. The loss of potassium directly leads to hypokalemia (low potassium). The other options are inconsistent with the pathophysiology of purging.

Concept Tested & Keywords

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E6 Nursing Fundamentals Taylor p. 779-781

E6 Nursing Fundamentals Potter Perry 12e Part 5 p. 53-55

E6 Kaplan Sadock's Synopsis of Psychiatry-2022 (pp 1-3768 of 3768) p. 1509-1511

Practise the full NORCET 10 Mains

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