66736-0

LOINC code 66736-0 identifies "Normalized silica clotting time of Platelet poor plasma". The Silica Clotting Time (SCT) refers to a version of the activated partial thromboplastin time (aPTT) in which: 1) silica replace kaolin as activator in order to make the test amenable to automation (since kaolin is opaque) and 2) there is a screening reagent with very low phospholipid concentration, diminished compared to the standard aPTT reagent, to maximize sensitivity to lupus anticoagulant (LAC) and 3) there is a confirmatory reagent which uses excess phospholipid in an attempt to neutralize the putative LAC. (Original reference: Chantarangkul et al., Silica Clotting Time (SCT) as a Screening and Confirmatory Test Detection of the Lupus Anticoagulants. 1992. Thrombosis Research 67:355-365.) The normalize SCT ratio is calculated as follows: (Patient Screen Result in seconds / Mean Normal Screen Result in seconds) / (Patient Confirm Result in seconds / Mean Normal Confirm Result in seconds). The prototype test described by this code is the HemosIL(TM) Silica CLotting Time test. LabCorp performs a test similar to the screening step called "Partial Thromboplastin Time (PTT), Lupus Anticoagulant" (LabCorp #117002) which also uses silica and diminished PL, but apparently they do not report it as a normalized ratio.

This code measures Normalized silica clotting time in PPP. It belongs to the COAG class in the LOINC classification.

LOINC (Logical Observation Identifiers Names and Codes) is a universal standard for identifying laboratory and clinical observations. It is maintained by the Regenstrief Institute and used worldwide for health data exchange.