We have constructed a reference model to facilitate comparison of serum @entity442 values among @entity1 , and thereby to improve the value of @entity442 measurements for diagnosis. The data set consists of serum values measured in 969 samples from 468 healthy @entity1 and adolescents (232 males, 236 females; ages, 1.1-18.3 yr). One sample per @entity1 was used for the model, each being selected so as to provide sufficient observations for each stage of puberty. The samples not selected were used to validate the reference data. The @entity442 values were log transformed, and multiple regression analysis was used in the model-building process. The best linear model, which converts serum @entity442 concentrations into SD scores and explains 66% of the variation in logIGF-I values, includes the variables of age, gender, and puberty, and takes the interactions among these variables into account. In prepubertal and early pubertal @entity1 , the relationship between age and logIGF-I was positive, with greater effect in @entity1 older than 8 yr. In mid-puberty, logIGF-I values were higher in @entity1 than in @entity1 of the same age, up to 16 yr of age. Among @entity1 , the most pronounced positive relationship between age and logIGF-I occurred in mid-puberty, whereas the relationship between age and logIGF-I among @entity1 in mid-puberty is fairly constant. In late puberty, logIGF-I values were higher than earlier in puberty, and there was a negative relationship with age in both @entity1 and @entity1 . Instead of separate models for each combination of puberty and gender, estimating a single regression model permits simultaneous estimation of all explanatory variables and uses all observations in the data set, thereby making it easier to select those variables that have a significant effect on logIGF-I. Our model shows that @entity442 levels are related to age during each stage of puberty. The model also accounts for the fact that serum @entity442 concentrations during puberty are different for @entity1 and @entity1 .

Reference values for XXXX throughout childhood and adolescence: a model that accounts simultaneously for the effect of gender, age, and puberty.

@entity1 :: ('9606', 'Species') :: ['children', 'boys', 'girls', 'child'] @entity442 :: ('3479', 'Gene') :: ['IGF-I']
@entity442 :: (3479,Gene) :: ['IGF-I']
