Biochemical analytes in centrifuged blood samples could be affected by the age of subjects in different time periods and storage temperatures.

Background and objectives: Collection and providing standard blood samples for examination is critical for all medical laboratories. Currently, for all blood samples taken from the elderly and young people, the same preparation protocol is applied. We hypothesized that the blood taken from older individuals is more vulnerable to preparation conditions compared with the younger ones. This study aimed to assess the effect of storage duration and temperature on biochemical analytes in serum samples taken from old and young participants.

Materials and methods: Blood samples from 30 healthy participants including 15 young people (eight males and seven females, 20-35 years old) and 15 elderly people (eight males and seven females, 60-75 years old) were collected. For each participant, serum sample tubes stored at different time intervals (2 and 24 h) and temperatures (4°C, 25°C, and - 20°C). The biochemical analytes were examined by an automated analyzer. Total antioxidant capacity was assayed by a commercial kit. Nitric oxide metabolites were measured by Griess reagent.

Results and conclusion: Intragroup analysis in young and older participants showed that lactate dehydrogenase levels were significant in 2 h incubation time at 20-24°C and in 24-h incubation times at 20-24°C and 4°C compared with the baseline time (T0) (P < 0.05). Intergroup analysis showed that glucose and urea levels were higher among the older participants than the youth group at baseline and 24 h times (P < 0.05). Furthermore, the magnesium and nitric oxide levels were higher in the youth group than the elderly ones at baseline and 24 h times (P < 0.05).