IBD IBD Disease Monitoring and Activity Assessment 2 — Questions and Answers
Question 1: Fecal calprotectin levels greater than 250 μg/g in a clinically quiescent IBD patient most likely indicate:
- Normal bowel function
- Subclinical mucosal inflammation (Correct answer)
- Colorectal carcinoma
- Bacterial superinfection
Correct answer: Subclinical mucosal inflammation
Elevated fecal calprotectin (>250 μg/g) in a patient without active symptoms suggests ongoing subclinical mucosal inflammation not apparent from clinical assessment alone, warranting endoscopic reassessment.
Question 2: Which serum antibody is most strongly associated with Crohn's disease and is used as part of serological testing in IBD workup?
- pANCA (perinuclear anti-neutrophil cytoplasmic antibody)
- ASCA (anti-Saccharomyces cerevisiae antibody) (Correct answer)
- Anti-dsDNA antibody
- Anti-cardiolipin antibody
Correct answer: ASCA (anti-Saccharomyces cerevisiae antibody)
ASCA (anti-Saccharomyces cerevisiae antibody) is most strongly associated with Crohn's disease, while pANCA is more associated with ulcerative colitis; their combination helps differentiate between the two conditions.
Question 3: Therapeutic drug monitoring (TDM) for infliximab in IBD patients primarily involves measuring:
- Drug toxicity and hepatic metabolite levels
- Serum trough drug concentrations and anti-drug antibodies (Correct answer)
- Stool drug excretion rates
- Renal clearance of the biologic
Correct answer: Serum trough drug concentrations and anti-drug antibodies
TDM for infliximab measures serum trough concentrations (drawn just before the next infusion) and anti-drug antibodies to guide dose optimization and identify the cause of primary or secondary loss of response.
Question 4: Which laboratory pattern is most characteristic of iron deficiency anemia due to chronic intestinal bleeding in IBD?
- Elevated MCV with low hemoglobin
- Low ferritin, low serum iron, and elevated TIBC (Correct answer)
- Elevated ferritin with low hemoglobin
- Normal iron studies with low reticulocyte count
Correct answer: Low ferritin, low serum iron, and elevated TIBC
Iron deficiency anemia from chronic GI blood loss presents with low ferritin (depleted stores), low serum iron, and elevated TIBC (total iron-binding capacity), reflecting the body's compensatory upregulation of iron-transport protein.
Question 5: Which vitamin deficiency requires specific monitoring in patients with Crohn's disease affecting the terminal ileum or following ileal resection?
- Vitamin A
- Vitamin C
- Vitamin B12 (cobalamin) (Correct answer)
- Vitamin K
Correct answer: Vitamin B12 (cobalamin)
Vitamin B12 absorption occurs exclusively in the terminal ileum via intrinsic factor; Crohn's disease involving this segment or ileal resection impairs B12 uptake, necessitating regular monitoring and parenteral supplementation.
Question 6: A patient with UC on azathioprine develops a WBC of 2.1 × 10³/μL. What is the most appropriate immediate management?
- Continue azathioprine and recheck CBC in 1 month
- Reduce dose and add G-CSF growth factor
- Immediately discontinue azathioprine and consult hematology (Correct answer)
- Switch to 6-mercaptopurine at equivalent dose
Correct answer: Immediately discontinue azathioprine and consult hematology
A WBC <3 × 10³/μL represents significant leukopenia, a serious azathioprine toxicity requiring immediate drug discontinuation and hematology consultation to prevent life-threatening opportunistic infections.
Question 7: C-reactive protein (CRP) is a more reliable marker of disease activity in which IBD type compared to the other?
- Ulcerative colitis only
- Crohn's disease, particularly with ileal involvement (Correct answer)
- Microscopic colitis
- Indeterminate colitis only
Correct answer: Crohn's disease, particularly with ileal involvement
CRP reliably reflects systemic inflammation in Crohn's disease, especially transmural ileal disease, whereas UC patients frequently have near-normal CRP levels even with active mucosal inflammation confined to the colon.
IBD IBD Disease Monitoring and Activity Assessment 2
Fecal calprotectin levels greater than 250 μg/g in a clinically quiescent IBD patient most likely indicate: