What is the appropriate workup for a 40-year-old male with one month of lower abdominal pain who takes lamictal (lamotrigine), evenity (romosozumab), and taltz (ixekizumab)?

Workup for One Month of Lower Abdominal Pain in a 40-Year-Old Male

CT abdomen and pelvis with IV contrast is the most appropriate initial imaging study for this patient with chronic lower abdominal pain, given the need to evaluate for diverticulitis, inflammatory bowel disease (particularly given his immunosuppressive therapy with Taltz), malignancy, and other intra-abdominal pathology. 1

Medication-Related Considerations

Before proceeding with standard workup, recognize that this patient's medication regimen raises specific concerns:

• Taltz (ixekizumab) is an IL-17 inhibitor that carries a black box warning for inflammatory bowel disease (IBD), with Crohn's disease occurring in 0.1% and ulcerative colitis in 0.2% of patients 2
• IBD exacerbations occur at higher rates in patients on IL-17 inhibitors compared to placebo, making this a critical diagnostic consideration 2
• The unusual combination of Evenity (romosozumab, for osteoporosis) and Taltz (for psoriasis/psoriatic arthritis) in a 40-year-old male suggests complex underlying conditions that may complicate the clinical picture

Initial Laboratory Workup

Obtain the following tests to guide diagnosis and imaging decisions:

• Complete blood count (CBC) - leukocytosis suggests diverticulitis, appendicitis, or other inflammatory processes 3, 4
• C-reactive protein (CRP) - particularly important given immunosuppressive therapy; CRP >140 mg/L suggests complicated disease requiring more aggressive management 1
• Comprehensive metabolic panel - evaluate electrolytes, renal function, and hepatobiliary markers 4
• Urinalysis - hematuria indicates urolithiasis; pyuria suggests urinary tract infection 3
• Lipase - if upper abdominal component to pain 4
• Fecal calprotectin - if IBD is suspected given Taltz use 1

Imaging Strategy

CT abdomen/pelvis with IV and oral contrast is rated 8-9 (usually appropriate) by the American College of Radiology for nonlocalized abdominal pain and is the single best test to evaluate the broad differential in this patient 1, 3:

• Detects diverticulitis with high accuracy 1, 3
• Identifies IBD complications (abscess, fistula, stricture) 1
• Evaluates for malignancy (1.9% prevalence in patients with diverticulitis-like symptoms) 1
• Assesses for other causes: appendicitis, bowel obstruction, urolithiasis, abscesses 1

Avoid plain radiography - it has low sensitivity and provides unnecessary radiation exposure without diagnostic benefit for chronic lower abdominal pain 3

Colonoscopy Timing

Schedule colonoscopy 6-8 weeks after CT imaging if no recent high-quality colonoscopy within the past year 1:

• Essential to exclude colon cancer (1.9% prevalence in diverticulitis patients, 7.9% in complicated cases) 1
• Evaluates for IBD given Taltz-associated risk 2
• Should be performed sooner if alarm symptoms present: change in stool caliber, iron deficiency anemia, blood in stool, weight loss 1
• Delay of 6-8 weeks reduces perforation risk and patient discomfort 1

Differential Diagnosis Priority

Given the one-month duration and medication profile, prioritize:

1. Drug-induced IBD (Crohn's disease or ulcerative colitis from Taltz) 2
2. Diverticulitis (most common cause of left lower quadrant pain in adults) 1, 5
3. Visceral hypersensitivity (common after inflammatory episodes, affects ~45% at 1 year) 1
4. Colorectal malignancy (must be excluded) 1
5. Chronic diverticular inflammation or stricture 1

Management of Negative Workup

If CT and colonoscopy are negative, consider visceral hypersensitivity and treat with low-dose tricyclic antidepressant 1:

• Tricyclic antidepressants have analgesic effects independent of mood effects, with efficacy in 1-3 weeks 1
• This is common after inflammatory episodes and does not require further invasive testing 1
• Reassure the patient that ongoing symptoms are common and often attributable to visceral hypersensitivity 1

Critical Pitfalls to Avoid

• Do not assume chronic pain is benign - the one-month duration requires imaging to exclude serious pathology 1
• Do not perform colonoscopy before CT - CT should guide the need for and timing of endoscopy 1
• Do not overlook drug-induced IBD - Taltz specifically increases this risk and requires high clinical suspicion 2
• Do not use opioids for chronic abdominal pain - they risk addiction, paradoxical pain amplification, and narcotic bowel syndrome 1