Answer: D. Her abnormal laboratory values could be the result of small bowel bacterial overgrowth or could be a lack of consistency taking her vitamins. Most patients with small bowel bacterial overgrowth have no laboratory abnormalities. Abnormal laboratory findings are more commonly seen in patients with anatomic abnormalities such as Roux-en-Y gastric bypass, however. Anemia and hypoalbuminemia are common abnormalities in these patients. Deficiencies in calcium, magnesium, iron, vitamin B12, and fat-soluble vitamins are not as common, however, and if present, may indicate small bowel bacterial overgrowth. If vitamin deficiencies are present in a person who has undergone Roux-en-Y gastric bypass surgery, especially if the person reports consistent vitamin use as well as diarrhea, bloating, and abdominal discomfort, small bowel bacterial overgrowth should be suspected.
Mrs. M reports taking her vitamins consistently. In fact, she is taking significantly more vitamin supplementation than is typical for those who have had Roux-en-Y gastric bypass surgery and yet she continues to have vitamin deficiencies. The fat-soluble vitamins are of particular interest because she is taking extra vitamin A, D, and E and does not have satisfactory levels of vitamin A and E. Her vitamin D level is in the satisfactory range; however, to achieve this, the patient is taking 50,000 units of vitamin D twice weekly. This is additional reasonable evidence to suspect small bowel bacterial overgrowth.