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Studies have often used the human bone turnover factor as a leading indicator of bone condition recently, hoping to judge the human bone condition in a shorter time interval. Bone formation factor (P1NP) and bone resorption factor (BCTX) are the most commonly used bone turnover factors. After reviewing the literatures, this study decided to select these two bone turnover factors as the research targe. Nowadays, the research on bone turnover factors mostly uses invasive methods. In terms of non-invasive research, the use of urine as a sample is limited to bone resorption factors. The research which using saliva as the sample, is no literature to establish the relationship between human blood and bone turnover factors in saliva. This study is also the first study to measure human serum and saliva at the same time and analyze the correlation between serum and saliva.
There are two types of sample measurement methods in this study; invasive detection uses Roche Cobas e411 for electrochemiluminescence immunoassay (ECLIA) to measure P1NP and BCTX in the subjects' serum, non-invasive detection uses enzyme-binding immunosorbent assay (ELISA) to measure P1NP and BCTX in the saliva of subjects with commercial sandwich-type and competitive ELISA KIT. Since some of the saliva BCTX samples are below the detection limit, this study also proposes a method to improve the detection limit of ELISA: increase the number of test sets and select best of three. Results show that whether it is the competition ELISA or the sandwich method, the detection limit of the ELISA is obviously lower than the detection limit of only three test groups. It is verified that this method is very effective for improving the detection limit.
Once the sample data is obtained, serum and saliva correlation analysis is performed on each subject respectively; there are two methods: Pearson Correlation Analysis and Spearman's Rank Correlation Analysis. After correlation analysis, it is concluded that the correlation between the subjects' P1NP blood and saliva is highly correlated(r = 0.9) and p-value (p =1.06 x 10-12 << 0.05), which means that the serum PINP concentration can be estimated by measuring the saliva P1NP concentration in the human body, and then the human bone condition can be judged. The correlation between the subjects' BCTX blood and saliva is moderately correlated(r = 0.54) and p-value (p = 0.004 <0.5), which means that the BCTX concentrations of the subjects' blood and saliva only have a certain degree of trend similarity, but the blood concentration cannot be estimated for a single subject's saliva concentration.