Table 2.

Correlations of serum concentrations of different forms of 25-hydroxyvitamin D (25(OH)D), vitamin D-binding protein, albumin, weight, and chronic kidney disease-mineral and bone disease (CKD-MBD) measures by CKD stages

	Total 25(OH)D	Bioavailable 25(OH)D	Free (measured) 25(OH)D	Free (calculated) 25(OH)D	VDBP
CKD 2–3 (n = 22)
Bioavailable 25(OH)D	0.74**
Free (measured) 25(OH)D	0.77**	0.98**
Free (calculated) 25(OH)D	0.87**	0.74**	0.73**
VDBP	0.13	− 0.03	0.11	− 0.29
Albumin	− 0.54**	− 0.13	− 0.20	− 0.45**	− 0.15
Calcium (Cor)	0.31	0.10	0.16	0.14	0.51**
Phosphate	0.14	0.08	0	0.29	− 0.21
PTH	− 0.09	0	− 0.01	0.03	− 0.25
Weight	− 0.40	− 0.30	− 0.26	− 0.34	− 0.16
Dialysis (n = 18)
Bioavailable 25(OH)D	0.94**
Free (measured) 25(OH)D	0.92**	0.96**
Free (calculated) 25(OH)D	0.94**	0.95**	0.96**
VDBP	− 0.35	− 0.41*	− 0.47**	− 0.53**
Albumin	0.15	0.25	0.12	0.24	− 0.24
Calcium (Cor)	0.08	0.02	0.11	0.11	0
Phosphate	− 0.27	− 0.33	− 0.29	− 0.38	− 0.07
PTH	− 0.13	− 0.10	0	− 0.08	− 0.30
Weight	− 0.46*	− 0.52**	− 0.57**	− 0.52**	0.09
Transplant (n = 21)
Bioavailable 25(OH)D	0.67**
Free (measured) 25(OH)D	0.64**	0.98**
Free (calculated) 25(OH)D	0.94**	0.79**	0.79**
VDBP	− 0.14	− 0.59**	− 0.65**	− 0.42*
Albumin	− 0.14	0.08	− 0.02	− 0.19	0.22
Calcium (Cor)	− 0.19	0.02	0.08	− 0.08	− 0.07
Phosphate	− 0.07	− 0.06	− 0.05	− 0.04	0.11
PTH	− 0.71**	− 0.73**	− 0.72**	− 0.74**	0.16
Weight	− 0.04	− 0.23	− 0.30	− 0.16	0.36

Data represent spearman correlation. * p < 0.1; ** p < 0.05