A 3-Year-Old Boy Is Brought to the Office for Evaluation

A 3-year-old boy is brought to the office for evaluation of chronic constipation.  The patient first experienced difficulty stooling when he began toilet training several months ago, and the symptoms have persisted.  He produces one small, hard stool every 3-4 days and often cries during defecation.  The patient also has periodic abdominal pain that is relieved by defecation.  He has no difficulty urinating and no history of encopresis.  Initially, his diet consisted of cow's milk and assorted meats and starches.  His parents have adjusted the diet to include more water and a variety of high-fiber fruits and vegetables, but there has been no improvement in his symptoms.  The patient uses inhaled beta-agonists as needed for wheezing due to reactive airway disease that is triggered by upper respiratory infections.  His mother has hypothyroidism and type 1 diabetes mellitus, and his maternal uncle has cystic fibrosis; otherwise, family history is insignificant.  Review of growth chart shows weight tracking at the 25th percentile and height at the 40th percentile.  Physical examination reveals an awake, alert child in no distress.  He has no rhinorrhea and the pharynx and tympanic membranes appear normal.  The neck is supple without adenopathy.  S1 and S2 are normal without murmurs, and the lungs are clear to auscultation bilaterally.  The abdomen is soft, nontender, and nondistended without organomegaly.  Bowel sounds are normoactive.  There is palpable stool in the left lower quadrant.  Firm stool is also palpable in the rectal vault.  There is a small anal fissure.  Which of the following long-term daily therapies will most likely benefit this patient?

A) Oral osmotic laxative therapy
B) Oral pancreatic enzyme replacement
C) Oral stimulant laxative therapy
D) Oral thyroid hormone replacement
E) Rectal enemas