The comparison of parathyroid hormone degradation effect by various protease inhibitors in blood specimen.
BACKGROUND
The objective of this study was to evaluate the role of proteases on the degradation of parathyroid hormone (PTH) in blood samples.


METHODS
Protease inhibitors with specificity against serine proteases (aprotinin), cysteine proteases (E-64), serine and cysteine proteases (leupeptin), metalloproteases (EDTA), or a protease inhibitor cocktail with a broad spectrum of inhibitory activity were added to blood samples. After storage at room temperature (0-48 hr), PTH levels were measured.


RESULTS
PTH levels in samples with the protease inhibitor cocktail did not change significantly after 48 hr of storage at room temperature, but the average PTH levels decreased by 40.7% and 20.1%, in samples stored at room temperature and stored at 4 degrees C without protease inhibitors, respectively. PTH levels in samples with leupeptin were stable for up to 24 hr. After 48 hr, the mean PTH levels decreased by 17.1%, 16.0%, 26.2%, and 32.1%, with 500 KIU/mL aprotinin, 100 micromol/L leupeptin, 10 micromol/L E-64, and 10 micromol/L EDTA, respectively, in the samples stored at room temperature.


CONCLUSIONS
The decrease in PTH levels in blood samples seemed to be due to the degradation of PTH by proteases. Various proteases, including especially serine proteases, would act together to degrade PTH in blood specimen. The PTH degradation may be inhibited in blood specimen with protease inhibitor cocktail.
Kim
Yeong Sic
YS
Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
Kwon
Hi Jeong
HJ
Lee
Hae Kyung
HK
D007611:Aprotinin / Q000494:pharmacology; D001800:Blood Specimen Collection; D004492:Edetic Acid / Q000494:pharmacology; D005260:Female; D006801:Humans; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D007976:Leupeptins / Q000494:pharmacology; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood* / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology*; D013997:Time Factors
D007976:Leupeptins; D010281:Parathyroid Hormone; D011480:Protease Inhibitors; D007611:Aprotinin; D004492:Edetic Acid; D007930:Leucine; C032854:leupeptin; C024974:E 64