Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (914 page)

   Ethylene glycol is metabolized to glycoaldehyde, glycolic acid, glyoxylic acid, oxalic acid, formic acid, and carbon dioxide. These acids may interfere with testing of ethylene glycol and cause elevation of some immunoassay tests for lactate/lactic acid, triglycerides.

   Avoid serum separator tubes and gels (may impact results).

FACTOR V LEIDEN MOLECULAR ASSAY
*

   Definition

   Factor V Leiden results from a
R506Q
mutation in the
F5
gene encoding factor V and is associated with increased risk of thrombophilia (OMIM# 188050). Heterozygosity for the factor V Leiden
R506Q
mutation is associated with resistance to activated protein C and a 5- to 10-fold increased risk of venous thrombosis. Homozygosity for this mutation is associated with resistance to APC and an approximately 80-fold increased risk of venous thrombosis. Other factors can further increase the risk of thrombosis.

   
Normal values:
negative or no mutations are found.

   Use

   Factor V Leiden testing should be performed in the following cases:

   A first occurrence of a venous thrombotic embolism (VTE) before age 50 years

   A first unprovoked VTE at any age

   A history of recurrent VTE

   Venous thrombosis at unusual sites (e.g., cerebral, mesenteric, portal or hepatic veins)

   VTE during pregnancy or the puerperium

   VTE associated with use of oral contraceptives or hormone replacement therapy