Livedo: benign livedo reticularis (no tests) or livedo racemosa (initial work-up)

• No tests if the livedo is typically physiological and the examination is normal.

Laboratory tests (fasting from fat if cryoglobulins)

• State the context (livedo racemosa) and any anticoagulant treatment on the request form: type, dose, time of the last dose.
• Lupus anticoagulant (citrate tube)
• Anticardiolipin antibodies IgG and IgM
• Anti-beta-2-glycoprotein I antibodies, IgG and IgM
• FBC (platelets)
• PT, aPTT
• CRP
• Antinuclear antibodies (ANA)
• Serum creatinine with eGFR
• Urine protein:creatinine ratio (spot sample)if neededIf hypertension or abnormal renal function: antiphospholipid-associated nephropathy presents with hypertension, impaired renal function and proteinuria; the PNDS includes spot-sample proteinuria in the extension work-up of APS ^[2].
• Cryoglobulins (sample collected and transported at 37 °C, fasting from fat; laboratory with the necessary equipment)if neededIf purpura, acrosyndrome, leg ulcer or hepatitis C: cryoglobulinaemia causes a pathological livedo with large irregular meshes ^[6]. Sample collected with pre-warmed equipment at 37 °C, transported at 37 °C, patient fasting from fats for 4 to 6 hours; if these conditions cannot be met, it is better not to take the sample ^[6]. The Sajjan review lists it among the useful screening tests ^[1].
• Hepatitis C serology (if cryoglobulins positive or risk factor)if neededHCV is responsible for 40 to 60% of mixed cryoglobulinaemias ^[6].

12 weeks later, if an antiphospholipid antibody is positive

• If an antibody is positive: repeat it 12 weeks later, away from any inflammation.