Rheumatology

Question 1

MOA of Allopurinol***

Answer 1

• Inhibit xanthine oxidase that converts hypoxanthine to xanthine and xanthine to uric acid;
• This increase the reutilization of hypoxanthine and xanthine for nucleotide and nucleic acid synthesis by HGPRTase
• Cause feedback inhibition of de novo purine synthesis
• End result: decrease urine and serum uric acid concentration

Question 2

Side effect of allopurinol***

Answer 2

• Fever
• Decrease WCC
• Steven Johnson Syndrome

Question 3

When to start Allopurinol***

Answer 3

• If >1 attack in 12 months
• Tophi
• Renal stones

Question 4

Risk factor for gout

Answer 4

> Reduce urate excretion

• Men
• Impaired renal function
• Diuretics

> Excess urate production

• Dietary
• Tumor lysis syndrome

Question 5

Physical examination sign for SLE**

Answer 5

> Head and face

• Alopecia
• Butterfly rash
• Discoid rash
• Oral ulcers

> Lung
- Pleural effusion

> Heart
- Pericardial rub

> Bedside test
- Urine dipstick (proteinuria, hematuria)

Question 6

Investigation for SLE**

Answer 6

> Establish diagnosis

• Autoantibodies (eg: ANA, anti-ds DNA, antiphospholipid antibodies)
• Complement level (decrease C3, C4)

> Other

• FBC (leukopenia, mild anemia, thrombocytopenia)
• ESR
• Renal profile (elevated creatinine)
• Urinalysis (cellular cast)

Question 7

Management for SLE***

Answer 7

> DMARDs

• Hydroxychloroquine: for all SLE
• Corticosteroid: acute flare
• Immunosuppressive (eg: methotrexate): poor symptoms control despite hydroxychloroquine and steroid
• Rituximab: severe renal and extrarenal disease refractory to immunosuppressive

> Adjunctive

• Rashes: topical steroid, sunscreen
• Arthralgia: NSAIDs

Question 8

How to differentiate psoriatic and SLE rash*

Answer 8

> Psoriasis

• Well-demarcated
• Erythematous plaques
• Coarse scale

> SLE

• Malar rash: photosensitive
• Discoid rash: erythematous patches with keratotic scaling over sun-exposed area of the skin

Question 9

Janeway lesion vs Osler node

Answer 9

> Janeway lesion

• Non-tender
• Septic emboli -> micro abscesses with neutrophils infiltration of capillaries

> Osler nodes

• Tender
• Localized immune-mediated vasculitis caused by septic emboli

Question 10

Diagnostic criteria for SLE*

Answer 10

(4 or more criteria met: at least 1 clinical and 1 lab) or (biopsy proven lupus nephritis + ANA/ anti-DNA)

Criteria (SOAP BRAIN)

• Serositis (pleuritis, pericarditis)
• Oral ulcer
• Arthritis
• Photosensitivity, Malar, Discoid rash
• Blood (anemia, thrombocytopenia, leukopenia)
• Renal involvement
• Antibodies (ANA)
• Immunologic (Anti-dsDNA, antiphospholipid)
• Neurologic (seizure, psychosis)

Question 11

Inflammatory vs Degenerative joint pain

Answer 11

> Inflammatory

• Duration of morning stiffness is long
• Stiffness improves with movement
• Worsen by prolonged inactivity

> Degenerative

• Duration of stiffness is shorter
• Pain worsened with activity
• Relieved with rest

Question 12

If RA patient presented with neurological deficits, what to consider?

Answer 12

• Cervical subluxation

Question 13

What are tophi?

Answer 13

• Painless, firm, nodular subcutaneous deposit of monosodium urate
• Common site of involvement: digits of hands and feet, ear pinna, bursa around elbow and knee, Archilles tendon

Question 14

Investigation for rheumatoid arthritis

Answer 14

> To establish the diagnosis

• Autoantibodies (eg: rheumatoid factors - +ve in 70%, anti-CCP)
• Radiograph of the hand: soft tissue swelling , pencil in cup deformity, periarticular cyst, juxta-articular osteopenia, joint space narrowing

> Other investigation

• CRP and ESR
• FBC: anemia
• Fasting blood glucose and lipid: common association