Laboratory diagnosis of the antiphospholipid syndrome: a plethora of obstacles to overcome.

The antiphospholipid antibody syndrome (APS) is defined by two major elements: the presence in plasma of auto-antibodies, i.e. antiphospholipid antibodies and the occurrence of clinical features, categorised as vascular thrombosis or pregnancy morbidity. In contrast to recent reviews on the physiopathology of APS, the present review focuses on the laboratory diagnosis of APS. The original clinical and laboratory criteria that defined patients with APS were set in 1998 in the so-called Sapporo criteria. Although a revision of these criteria was published in 2006, a number of questions on the laboratory diagnosis of APS remain unresolved. The highlight in this review will therefore be on the potential and limitations of the detection of the lupus anticoagulant, as an established laboratory criterion for the diagnosis of APS. The strengths and weaknesses of the current laboratory guidelines are discussed against our current insight in the physiopathology of APS.