A 78-year-old male nursing home resident is brought to the physician because of abdominal pain and discomfort. He has a history of advanced dementia and is only partially able to verbalize his symptoms. He has had intermittent abdominal discomfort for years, with no other related symptoms. He denies diarrhea and rectal bleeding but has not had a bowel movement in approximately 5 days. The patient is largely bed-bound, and only has minimal activity with the help of nurses and physical therapists. Past regular colonoscopies have shown only benign lesions. His other medical problems include dementia, coronary artery disease, hypertension, spinal stenosis, and osteoarthritis of his hips and knees. Abdominal examination does not show tenderness, masses, or hepatosplenomegaly, although fullness is appreciated. The remainder of the examination shows no abnormalities. Polyethylene glycol is administered and produces a bowel movement within 24 hours. The mechanism of action of polyethylene glycol in this patient is most similar to the pathophysiology of which of the following disorders?

Question

A 78-year-old male nursing home resident is brought to the physician because of abdominal pain and discomfort.  He has a history of advanced dementia and is only partially able to verbalize his symptoms.  He has had intermittent abdominal discomfort for years, with no other related symptoms.  He denies diarrhea and rectal bleeding but has not had a bowel movement in approximately 5 days.  The patient is largely bed-bound, and only has minimal activity with the help of nurses and physical therapists.  Past regular colonoscopies have shown only benign lesions.  His other medical problems include dementia, coronary artery disease, hypertension, spinal stenosis, and osteoarthritis of his hips and knees.  Abdominal examination does not show tenderness, masses, or hepatosplenomegaly, although fullness is appreciated.  The remainder of the examination shows no abnormalities.  Polyethylene glycol is administered and produces a bowel movement within 24 hours.  The mechanism of action of polyethylene glycol in this patient is most similar to the pathophysiology of which of the following disorders?

Quizplus · Accepted Answer

Eductional Objective: Polyethylene glycol is an osmotic laxative.  Diarrhea associated with lactase deficiency is also osmotic and occurs due to accumulation of nonabsorbable lactose in the intestinal lumen.  Magnesium hydroxide (and other magnesium-containing compounds, such as magnesium citrate) is another osmotic laxative that is often used, although its efficacy is questionable and there is not enough evidence to support its widespread use.

A 78-Year-Old Male Nursing Home Resident Is Brought to the Physician