. Author manuscript; available in PMC: 2022 Jun 21.

Published in final edited form as: Am J Nephrol. 2022 Feb 28;53(2-3):226–239. doi: 10.1159/000521386

Table 2.

Serum phosphate and related biomarkers

	CRIC	CKD-JAC
	Original	Original	Converted ^*	P-value
Serum phosphate, mg/dL	3.7 ± 0.7^*1	3.5 ± 0.6^*2	3.3 ± 0.6	<0.001^a
PTH, pg/mL	54 [35 - 90]^*1	81 [54 - 127]^*2	115 [77 - 179]	<0.001^a,w
25OHD, ng/mL	22.1 [13.5 - 32.7]^{*1, 3}	14.7 [9.5 - 21.8]^*2	13.7 [7.7 - 21.8]	<0.001^a,w
Intact FGF23, pg/mL	53 [40 - 73]^*4	57 [41 - 92]	NA	<0.001^b,w
C-terminal FGF23, RU/mL	145 [96 - 238]	NA	NA	NA

Data are expressed as mean ± S.D. or median [interquartile range]. Superscripts “a”, “b”, and “w” stand for the comparison between CRIC and converted CKD-JAC data, the comparison between random samples of CRIC and original CKD-JAC data, and the Wilcoxon rank-sum test, respectively; t-test was performed unless otherwise noted. Abbreviations: PTH, parathyroid hormone; 25OHD, 25-hydroxyvitamin D; FGF23, fibroblast growth factor-23.

CKD-JAC data converted to assay types used in CRIC. See Apendix for details

^*1

Originally in CRIC: Serum phosphate was measured by phosphomolybdate assay; Total PTH, by immunoradiometric assay; and 25OHD, by liquid chromatography and mass spectroscopy.

^*2

Originally in CKD-JAC: Serum phosphate was measured by enzymatic assay; Intact PTH, by electrochemiluminescence immunoassay; and 25OHD, by radioimmunoassay.

^*3

Measured in random samples (N=1690).

^*4

Measured in random samples at the same central laboratory of CKD-JAC (N=1132).