Dependence of TIMP-1 plasma levels on preanalytical specimen handling

Background: Tissue inhibitor of metalloproteinases-1 (TIMP-1) in
blood might be a helpful biomarker in various diseases. However,
various authors report that TIMP-1 is dependent on preanalytical
procedures. Our study was performed to determine how storage
conditions and time to centrifugation influence TIMP-1. Materials
and Methods: Twenty-six blood specimens were collected from each of
20 volunteers. Two specimens from each person were
centrifuged/measured within 1 h after venipuncture and frozen at
-80 degrees C. They were thawed once or twice within 72 h. Eight
specimens were stored at 20 degrees C in daylight, 8 at 20 degrees
C covered and 8 at 4 C in daylight. Four of each of these 8
specimens were mixed once a day until centrifugation. A mixed and
an unmixed specimen of each group was centrifuged/measured after 3,
6, 24 and 72 h. Results: TIMP-1 increased after freeze/ thaw (p
< 0.001). Mixing blood specimens more than once caused increased
TIMP-1 (p < 0.001). TIMP-1 increased within 3 h of storage (p
< 0.001). The increase was lower in specimens covered and
refrigerated (p < 0.001). Conclusion: TIMP-1 is unstable and has
to be evaluated carefully. Blood should be centrifuged directly
after venipuncture. For routine application, specimen handling must
be standardized and carefully followed. Research should be done on
specimens handled identically. Copyright (C) 2008 S. Karger AG,
Basel.