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.


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 degrees 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).


CONCLUSIONS
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.
Dresse
Marie
M
Institute of Clinical Chemistry, Klinikum Grosshadern, University of Munich, Munich, Germany.
Nagel
Dorothea
D
Ganser
Eva-Maria
EM
Davis
Gerard
G
Dowell
Barry
B
Doss
Robert
R
Stieber
Petra
P
D002498:Centrifugation; D005615:Freezing; D006801:Humans; D008027:Light; D013048:Specimen Handling / Q000379:methods*; D013997:Time Factors; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000097:blood*
D019715:Tissue Inhibitor of Metalloproteinase-1