Vitamin D deficiency may predispose patients to increased risk of kidney transplant rejection

Table 1 Demographic characteristics of the kidney recipients at the time of graft biopsy

Parameter	Patients, n = 52
Mean age, yr	41 ± 11.9
Male, n (%)/female, n (%)	38 (73.1)/14 (26.9)
DM, n (%)/HT, n (%)	15 (28.8)/25 (48.1)
Hemodialysis, n (%)/peritoneal dialysis, n (%)	43 (82.7)/6 (11.5)
Mean dialysis duration, yr	5.8 ± 4.71
Pre-emptive, n (%)	3 (5.8)
Donor type: Living, n (%)/Cadaver, n (%)	34 (65.4)/18 (34.6)
Donor sex: Male/female	29 (55.8)/23 (44.2)
Donor age in yr	49.6 ± 9.7
Time since transplantation, yr	5.91 ± 1.83
Number of HLA mismatches	3 ± 1
DGF, n (%)	9 (17.6)
DSA, n (%)	14 (27.5)
Cyclosporine/tacrolimus serum levels, ng/mL	545 ± 89/4.8 ± 0.8
MMF, gr/d	1.7 ± 0.3
Pre-transplant kidney failure etiology
DM, n (%)	15 (28.8)
HT, n (%)	25 (48.1)
Glomerulonephritis, n (%)	7 (13.5)
Post-renal kidney failure, n (%)	3 (5.8)
Unknown, n (%)	2 (3.8)

CSA: Cyclosporine A; DM: Diabetes mellitus; DGF: Delayed graft function; DSA: Donor-specific antibody; HLA: Human leukocyte antigen; HT: Hypertension; MMF: Mofetil mycophenolate; TAC: Tacrolimus.

Table 2 Comparison of demographic characteristics and laboratory findings in the low and high vitamin D level groups at the time of graft biopsy

Vitamin D level	Group 1 (> 15 ng/mL), n = 14	Group 2 (≤ 15 ng/mL), n = 38	P value
Age, yr	40 ± 11.9	41 ± 12.0	0.856
Male, n (%)	7 (50)	31 (81.6)	0.035
DM/HT, n (%)	2 (14.3)/6 (42.9)	13 (34.2)/19 (50)	0.300/0.759
Hemodialysis/peritoneal dialysis	12 (92.3)/1 (7.7)	31 (86.1)/5 (13.9)	1.00
Mean dialysis duration, yr	5.9 ± 4.5	5.6 ± 3.7	0.839
Preemptive, n (%)	1 (7.1)	2 (5.3)	1.00
Rejection, n (%)	1 (7.1)	24 (63.2)	< 0.001
CAN, n (%)	4 (28.6)	15 (39.5)	0.534
Number of HLA mismatches	3 ± 1	3 ± 1	1.00
ESRD actual, n (%)	7 (58.3)	10 (27)	0.80
Hemoglobin, g/dL	11.5 ± 2.0	10.7 ± 2.4	0.266
Glucose, mg/dL	106 ± 60.7	98 ± 33.9	0.433
Albumin, g/dL	4.0 ± 0.4	3.7 ± 0.6	0.063
Uric acid, mg/dL	7.1 ± 1.8	7.7 ± 1.5	0.276
Urea, mg/dL	68 ± 35.3	77 ± 38.6	0.416
Creatinine, mg/dL	2.08 ± 0.61	2.21 ± 1.22	0.702
eGFR, mL/min/1.73 m2	38 ± 18.3	41 ± 19.7	0.609
Proteinuria, g/d	1.0 ± 0.9	2.5 ± 3.1	0.261
Cholesterol, mg/dL	186 ± 36.9	177 ± 46.2	0.515
Triglyceride, mg/dL	178 ± 82.9	191 ± 110.1	0.877
Calcium, mg/dL	8.9 ± 0.99	8.7 ± 0.80	0.400
Phosphorus, mg/dL	4.8 ± 1.84	4.5 ± 1.86	0.657
PTH, pg/mL (range)	205 (78-927)	268 (59-955)	0.007
CRP, mg/dL	24 ± 48.2	21 ± 29.9	0.483

CAN: Chronic allograft nephropathy; CRP: C-reactive protein; DM: Diabetes mellitus; eGFR: Estimation glomerular filtration rate; ESRD: End-stage renal disease; HLA: Human leukocyte antigen; HT: Hypertension; PTH: Parathyroid hormone.

Table 3 Demographic characteristics and laboratory findings according to rejection status at the time of graft biopsy

Rejection	No	Yes	P value
Patients, n	27	25
Mean age, yr	42 ± 10.9	39 ± 12.9	0.316
Female, n (%)	16 (59.3)	22 (88.0)	0.020
DM, n (%)/HT, n (%)	7 (25.9)/13 (48)	8 (32.0)/12 (48)	0.629/0.991
Donor type Cadaver, n (%)	7 (25.9)	11 (44.0)	0.171
Donor age, yr	47.7 ± 9.6	51.8 ± 9.6	0.133
Time since transplantation, yr	4.4 ± 1.4	5.3 ± 3.1	0.236
Number of HLA mismatches	2.2 ± 1.2	2.6 ± 1.2	0.263
DSA, n (%)	0	14 (56.0)	< 0.001
Cyclosporine/tacrolimus serum levels, ng/mL	576 ± 98/4.7 ± 0.9	490 ± 29/4.9 ± 0.7	0.063/0.352
MMF, gr/d	1.7 ± 0.3	1.7 ± 0.3	0.601
ESRD actual, n (%)	5 (18.5)	12 (48)	0.024
Hemoglobin, g/dL	11.5 ± 2.2	10.4 ± 2.3	0.095
Glucose, mg/dL	95 ± 37.7	107 ± 46.7	0.399
Albumin, g/dL	4.0 ± 0.5	3.5 ± 0.6	0.001
Uric acid, mg/dL	7.3 ± 1.6	7.7 ± 1.6	0.364
Creatinine, mg/dL	1.78 ± 0.44	2.59 ± 1.40	0.016
eGFR, mL/min/1.73 m²	45 ± 19.3	36 ± 18.3	0.012
Cholesterol, mg/dL	177 ± 37.2	181 ± 49.8	0.810
Triglyceride, mg/dL	180 ± 103.4	196 ± 104.1	0.379
Calcium, mg/dL	8.8 ± 0.79	8.7 ± 0.92	0.562
Phosphorus, mg/dL	3.9 ± 1.51	5.3 ± 1.96	0.009
PTH, pg/mL (range)	197 (59-440)	310 (106-955)	0.022
Vitamin D, ng/mL	14.7 ± 7.2	9.7 ± 3.4	0.003
CRP, mg/mL	20 ± 24.9	23 ± 43.2	0.05

CRP: C-reactive protein; DM: Diabetes mellitus; DSA: Donor-specific antibody; eGFR: Estimation glomerular filtration rate; ESRD: End-stage renal disease; HLA: Human leukocyte antigen; HT: Hypertension; MMF: Mofetil mycophenolate; PTH: Parathyroid hormone.

Table 4 Univariate and multivariate regression analyses for rejection

	Univariate regressions				Multivariate regression
	B	OR	95%CI	P value	B	OR	95%CI	P value
Age	-0.02	0.97	0.93-1.02	0.381	-0.04	0.95	0.87-1.03	0.265
Sex, female	1.61	5.04	1.20-21.06	0.027	1.12	3.08	0.31-30.45	0.336
Donor type Cadaver, n (%)	0.46	1.58	0.50-5.00	0.434	1.52	4.60	0.71-29.77	0.109
Donor sex, female, n (%)	-0.33	0.71	0.23-2.15	0.555	0.40	1.50	0.26-8.38	0.643
Donor age, yr	0.03	1.04	0.98-1.10	0.192	0.40	1.04	0.95-1.13	0.340
DGF, n (%)	-0.22	0.80	0.18-3.40	0.763	-1.41	0.24	0.01-4.36	0.337
MMF, gr/d	0.78	2.19	0.69-6.97	0.183	0.84	2.32	0.33-16.37	0.397
Serum fosfor (mg/dL)	0.43	1.53	1.06-2.22	0.023	0.63	1.87	1.01-3.48	0.05
Vitamin D, ng/mL	-0.153	0.85	0.76-0.96	0.007	-0.12	0.88	0.72-1.06	0.196
PTH	0.01	1.00	1.00-1.01	0.052	0.01	1.00	0.99-1.00	0.516
Albumin (g/dL)	-1.49	0.22	0.07-0.68	0.008	-1.17	0.30	0.05-1.69	0.177
CSA serum level, ng/mL	-0.01	0.99	0.99-1.00	0.265	0.01	1.00	0.99-1.00	0.983
TAC serum level, ng/mL	0.167	1.18	0.92-1.51	0.189	0.02	1.01	0.54-1.89	0.955

CI: Confidence interval; CSA: Cyclosporine A; DGF: Delayed graft function; MMF: Mofetil mycophenolate; OR: Odds ratio; PTH: Parathyroid hormone; TAC: Tacrolimus.