Validation of heterologous radioimmunoassay for insulin-like Growth Factor - I in Camel

This study was undertaken to develop an heterologous radioimmunoassay method for measuring IGF-I in camel blood. Precision, accuracy and limit of quantitation were the principal parameters used to judge validity of an acid-ethanol extraction method. Blood was taken from twenty suckling dromedary females and their calves. Dams were divided into two body condition score groups (group 1: 5.2 .. 0.9 and group 2: 3.8 .. 0.6; P <0.0001). The precision expected by the intra and inter-assay variation was in the rage of 5-10% and 14-16%, respectively. In dilution buffer, recovery ranged from 98.4% in highest added quantity to 126.6% in lowest added quantity of IGF-I. In camel serum, recovery ranged from 92.4% to 107%. Sensitivity or displacement of the concentration of IGF-I in the diluted serum was acceptable until dilution 8 fold after what the precision of the recovery was very low. Dams and calves in group 1 had elevated (P<0.01) serum IGF-I concentration as compared to those in group 2 (41.6 .. 14.3 ng/ml and 248.3 .. 101.9 ng/ml vs. 26.6 .. 2.9 ng/ml and 90.1 .. 77.2 ng/ml, respectively). IGF-I was found to be less concentrated in dams than in calves in which the IGF-I serum concentration averaged 34.1 .. 12.7 ng/ml and 169.2 .. 119.7 ng/ml, respectively