Pharmacology · patient case with 2 questions
Rheumatoid arthritis managed with adalimumab and methotrexate
Patient: Female, 55 years old
Chief Complaint: “I need a crown replaced and my hands make brushing hard.”
Background: Rheumatoid arthritis of eight years' duration. Adalimumab (Humira) every other week and weekly oral methotrexate with folate supplementation. No other medications.
Vital Signs: BP 122/78 mmHg · HR 74 bpm · T 98.1°F
Findings: Symmetric swelling of the metacarpophalangeal and proximal interphalangeal joints with reduced grip strength. Limited mouth opening, 32 mm. Bilateral TMJ crepitus. Generalized plaque accumulation.
Question 1
Which laboratory test is the essential routine monitor for her METHOTREXATE therapy?
Show answer and explanation
Correct answer: A. Complete blood count with differential
- A. CORRECT. Methotrexate is a folate antagonist that suppresses the BONE MARROW, so the COMPLETE BLOOD COUNT WITH DIFFERENTIAL is the test that matters: leukopenia raises infection risk and impairs healing, thrombocytopenia adds bleeding risk, and macrocytic anaemia reflects the antifolate effect. Standard monitoring pairs the CBC with liver function tests and renal function, checked every two to three months once the dose is stable.
- B. A lipid panel has no role in methotrexate monitoring.
- C. Renal function is monitored, because methotrexate is renally cleared and impairment causes accumulation — but creatinine ALONE misses the marrow suppression, which is the effect that determines whether she can safely undergo a procedure.
- D. Calcium and phosphate relate to bone and parathyroid metabolism, not to antifolate toxicity.
Note: What this item adds is the MONITORING test and its interpretation. Two practical points: never prescribe an NSAID alongside methotrexate — NSAIDs reduce its renal clearance and can precipitate toxicity — and remember that adalimumab is a TNF-α inhibitor, so infection risk is compounded and postoperative healing warrants closer review.
Question 2
Which serological test is used as the initial screen when an autoimmune connective tissue disease is suspected?
Show answer and explanation
Correct answer: C. Antinuclear antibody (ANA) test
- A. Serum uric acid is the test for gout and hyperuricaemia, unrelated to connective tissue autoimmunity.
- B. The ESR rises in any inflammatory state, infection or malignancy. It measures activity, not aetiology, and points to nothing in particular.
- C. CORRECT. The ANTINUCLEAR ANTIBODY test detects autoantibodies against nuclear constituents and is the standard first-line SCREEN for autoimmune connective tissue disease. Its value is largely in its NEGATIVE predictive power — a negative ANA makes systemic lupus erythematosus very unlikely. A positive result is then refined by pattern and by specific antibodies: anti-dsDNA and anti-Sm for lupus, anti-Ro/SSA and anti-La/SSB for Sjögren syndrome, anti-centromere and anti-Scl-70 for systemic sclerosis. Note that ANA is positive in up to 15% of healthy people, so it must be interpreted with the clinical picture.
- D. CRP is an acute-phase reactant. Like the ESR it tracks inflammatory activity without identifying its cause.
Note: For rheumatoid arthritis specifically the more useful pair is RHEUMATOID FACTOR plus ANTI-CCP — anti-CCP being far the more specific and an early predictor of erosive disease. ANA is the broad screen across the connective tissue diseases; anti-CCP is the RA-specific one. Dentally, Sjögren syndrome is the overlap to watch for, since secondary Sjögren accompanies RA and brings xerostomia with rampant cervical caries.