Question

Write laboratory features of drug-induced lupus.

Hint:

The presence of anti-histone antibodies is a hallmark of drug-induced lupus and helps to distinguish it from systemic lupus erythematosus.

Answer 1

Step 1: Key Laboratory Features of Drug-Induced Lupus.
The following laboratory findings are commonly observed in patients with drug-induced lupus:
- Positive ANA (Antinuclear Antibody) test: Typically, a positive ANA with a homogeneous or speckled pattern is found.
- Anti-Histone Antibodies: The hallmark antibody for drug-induced lupus is anti-histone antibodies. They are found in high titers and are specific for DIL.
- Normal Complement Levels: Unlike in SLE, where complement levels are often low, drug-induced lupus usually shows normal complement levels (C3, C4).
- Elevated ESR (Erythrocyte Sedimentation Rate): A general marker of inflammation, ESR is often elevated in DIL.
Step 2: Differential Testing.
In cases where drug-induced lupus is suspected, it is important to differentiate it from other forms of lupus (like SLE). Specific tests for anti-histone antibodies are used for this purpose.