Circadian rhythm of bone formation biomarkers in serum of dromedary camels

The circadian rhythm of biomarkers of bone formation including osteocalcin and bone alkaline phosphatase (BAP) was studied in the serum of dromedary camels. Blood samples were collected every 60 min for 24 h from 10 healthy adult female camels. ELISA was used to determine the concentrations of serum osteocalcin and BAP. The results showed a marked fluctuation in the concentration of osteocalcin during the 24 h period with minimum and maximum levels at 13:00 (01:00 pm) and 18:00 (06:00 pm), respectively. Slight fluctuation was observed in the concentration of BAP with minimum and maximum levels at 01:00 am and 12:00 pm, respectively. The correlation between the two biomarkers was weak. It was concluded that it is important to fix the time of blood sampling for analysis of osteocalcin concentrations, but not for BAP.