engleski

SHORT-TERM STABILITY OF INSULIN IN SAMPLES FROM DIFFERENT BLOOD COLLECTION TUBE

BACKGROUND-AIM: Measurement of the levels of blood insulin, a hormone responsible for the blood glucose regulation, may be a useful tool for the assessment of insulin resistance in type 2 diabetes and metabolic syndrome management. However, sample type together with overall stability is of great importance because insulin is easily degraded by circulating peptidases. Previous reports indicate that concentration remains stable in EDTA plasma, but not serum samples for 24 hours. The aim of our study was to compare insulin levels in two sample types, recommended plasma from EDTA-containing tubes (BD™ Vacutainer™K3EDTA Tubes, USA) and a serum from tubes with a new generation of gel separator (BD Vacutainer™SST™, USA). Additionally, we assessed insulin stability in both sample types within 24 hour storage at room temperature and +4oC. METHODS: Venus blood was sampled from 18 volunteers parallel in SST-serum tubes and EDTA-containing tubes. After centrifugation, analysis was done immediately and after 24 hour storage in different temperature conditions (room temperature and +4oC). Plasma samples were transferred in secondary tubes while the serum separation was obtained by gel in SST-tubes. Insulin was measured on ADVIA Centaur-XP analytical system (Siemens Healthineers, USA). RESULTS: Passing Bablok regression analysis revealed proportional differences for insulin concentration in fresh samples from SST-serum compared to EDTA-plasma tubes (y =-3, 1115(95% CI = -18, 4947 to 3, 5230) + 1, 1531(95% CI = 1, 0228 to 1, 3646)x). Regarding sample stability, insulin levels in SST-serum samples were found to be significantly lower in both samples stored at room temperature and +4oC (P = 0, 0235), while EDTA-plasma samples obtained satisfactory stability (P = 0, 6599 ; Kruskall Wallis ANOVA). CONCLUSIONS: SST-serum tubes could not preserve insulin from degradation for 24 hour period regardless of the storage temperature.

insulin stability, EDTA-plasma, SST-serum gel separator tubes

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