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Comparison between Whole and Intact Parathyroid Hormone Assays
Author(s) -
Taniguchi Masatomo,
Tanaka Motoko,
Hamano Takayuki,
Nakanishi Shohei,
Fujii Hideki,
Kato Hitoshi,
Koiwa Fumihiko,
Ando Ryoichi,
Kimata Naoki,
Akiba Takashi,
Kono Takashi,
Yokoyama Keitaro,
Shigematsu Takashi,
Kakuta Takatoshi,
Kazama Junichiro James,
Tominaga Yoshihiro,
Fukagawa Masafumi
Publication year - 2011
Publication title -
therapeutic apheresis and dialysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.415
H-Index - 53
eISSN - 1744-9987
pISSN - 1744-9979
DOI - 10.1111/j.1744-9987.2011.00926.x
Subject(s) - parathyroid hormone , medicine , endocrinology , population , dialysis , guideline , calcium , pathology , environmental health
The standard measurement of parathyroid hormone (PTH) is the intact PTH (iPTH) assay, which is used for approximately 90% of Japanese dialysis patients. The iPTH assay reacts not only with 1–84 PTH, but also with large truncated fragments of non‐1–84 PTH, including 7–84 PTH. On the other hand, the whole PTH assay is specific for 1–84 PTH. The aim of the current study was to define the validity of both whole and intact PTH assays. A total of 738 hemodialysis patients were enrolled from twelve dialysis services. The serum PTH level was evaluated by both intact and whole PTH assays simultaneously. Non‐1–84 PTH was determined by subtracting the whole PTH value from that of the intact PTH assay. The median level of whole PTH was 121 pg/mL, and that of iPTH was 210 pg/mL. The whole PTH assay had a very high correlation with the iPTH assay ( r = 0.870, P < 0.001). For 43 out of 738 patients (5.8%) the value for intact PTH—whole PTH was <0. Both assays significantly correlated with non‐1–84 PTH ( P < 0.001), while the iPTH assay, particularly, had a very high correlation with non‐1–84 PTH ( r = 0.791). As a whole, 18% of the total population was misclassified into a different Japanese guideline category. Stratified by Japanese guideline classifications, 28% of patients within an iPTH target range were misclassified. Using Bland–Altman plot analysis, as the serum PTH level increased, there was a large difference between two assays. Both PTH assays correlate strongly, although the whole PTH assay may be more useful for precise evaluation of PTH function than the iPTH assay.