Undiagnosed
CBC
Chem 10
Urine pregnancy
ANA
ESR
Urinalysis
Bedside echocardiography if ill or hypotensive
(Consider anti-DNA, anti-Smith, anti-Nuclear, anti-phospholipid, C3,C4, direct Coombs')
Flare
Bedside echo if ill or hypotensive
CBC
Chem
Urinalysis
Urine pregnancy
As directed by organ system involved
Drug Induced<unk> 
Anti-histone-Ab positive 95% of the time
Make sure to review medications
High risk:
Procainamide (antiarrhythmic)
Hydralazine (antihypertensive)
Moderate to low risk:
Infliximab anti (TNF-α)
Etanercept anti (TNF-α)
Isoniazid (antibiotic)
Minocycline (antibiotic)
Pyrazinamide (antibiotic)
Quinidine (antiarrhythmic)
D-Penicillamine (anti-inflammatory)
Carbamazepine (anticonvulsant)
Oxcarbazepine (anticonvulsant)
Phenytoin (anticonvulsant)
Propafenone (antiarrhythmic)
Chlorpromazine (antipsychotic)
High risk:
Procainamide (antiarrhythmic)
Hydralazine (antihypertensive)
Moderate to low risk:
Infliximab anti (TNF-α)
Etanercept anti (TNF-α)
Isoniazid (antibiotic)
Minocycline (antibiotic)
Pyrazinamide (antibiotic)
Quinidine (antiarrhythmic)
D-Penicillamine (anti-inflammatory)
Carbamazepine (anticonvulsant)
Oxcarbazepine (anticonvulsant)
Phenytoin (anticonvulsant)
Propafenone (antiarrhythmic)
Chlorpromazine (antipsychotic)
Procainamide (antiarrhythmic)
Hydralazine (antihypertensive)
Infliximab anti (TNF-α)
Etanercept anti (TNF-α)
Isoniazid (antibiotic)
Minocycline (antibiotic)
Pyrazinamide (antibiotic)
Quinidine (antiarrhythmic)
D-Penicillamine (anti-inflammatory)
Carbamazepine (anticonvulsant)
Oxcarbazepine (anticonvulsant)
Phenytoin (anticonvulsant)
Propafenone (antiarrhythmic)
Chlorpromazine (antipsychotic)
Must differentiate disease activity (flare) from infection
Risk Factors for Infection 
Neutropenia/Lymphopenia
Hypocomplementemia
Immunosuppressive therapy (especially azathioprine )
Studies
CRP: sensitivity 100%, specificity 90% >1.35mg/dL 
PCT: sensitivity 75%, specificity 75%
Systemic lupus erythematosus
Rheumatoid arthritis
Polymyalgia rheumatica
Sjögren Syndrome
Scleroderma
Dermatomyositis
Juvenile idiopathic arthritis
Polymyositis