Table 2.

Parathyroid related characteristics of included patients.

Variables		Group0 (N = 634) N (%)	Group1 (N = 1,078) N (%)	Group2 (N = 765) N (%)	P
Carbon nanoparticles	No	119 (18.8)	278 (25.8)	414 (54.1)	<0.0001*
	Yes	515 (81.2)	800 (74.2)	351 (45.9)
Surgical extent	Unilateral CND	282 (44.5)	286 (26.5)	63 (8.2)	<0.0001*
	≥Bilateral CND	352 (55.5)	792 (73.5)	702 (91.8)
PG unintentionally resected	No	595 (93.8)	978 (90.7)	676 (88.4)	0.0019*
	Yes	39 (6.2)	100 (9.3)	89 (11.6)
Vitamin D deficiency	No	240 (37.9)	333 (30.9)	248 (32.4)	0.0111*
	Yes	394 (62.1)	745 (69.1)	517 (67.6)
PTH, pmol/L (Mean ± SD)	Pre	5.42 ± 1.61	5.66 ± 1.70	5.75 ± 1.63	0.0008*
	Post 1 day	2.59 ± 1.55	2.02 ± 1.28	1.71 ± 2.01	<0.0001*
	Post 1 month	4.12 ± 1.76	4.18 ± 2.30	4.09 ± 1.80	0.6454
	Post 3 months	4.52 ± 1.82	4.40 ± 2.17	4.81 ± 2.72	0.0515
	Post 6 months	4.40 ± 2.29	4.66 ± 2.11	4.84 ± 3.00	0.1183
	Post 12 months	4.58 ± 1.81	4.97 ± 2.74	4.55 ± 1.61	0.0676
	Post 24 months	4.34 ± 1.67	4.31 ± 2.34	4.78 ± 2.14	0.3242
Ca, mmol/L (Mean ± SD)	Pre	2.35 ± 0.42	2.33 ± 0.17	2.34 ± 0.13	0.6515
	Post 1 day	2.13 ± 0.15	2.11 ± 0.17	2.10 ± 0.16	0.0061
	Post 1 month	2.31 ± 0.16	2.3 ± 0.15	2.31 ± 0.13	0.7692
	Post 3 months	2.27 ± 0.16	2.26 ± 0.15	2.26 ± 0.15	0.3140
	Post 6 months	2.28 ± 0.15	2.26 ± 0.19	2.26 ± 0.14	0.0725
	Post 12 months	2.28 ± 0.15	2.28 ± 0.13	2.28 ± 0.17	0.8099
	Post 24 months	2.30 ± 0.16	2.27 ± 0.17	2.27 ± 0.11	0.2429
25-OH-VD, mmol/L (Mean ± SD)	Pre	46.83 ± 16.51	43.30 ± 15.76	45.04 ± 15.75	0.0352*
	Post 1 day	37.10 ± 14.71	32.95 ± 13.50	35.57 ± 16.40	0.0175*
	Post 1 month	50.33 ± 17.00	48.38 ± 16.77	50.55 ± 14.81	0.0280*
	Post 3 months	54.39 ± 16.32	51.10 ± 16.29	49.42 ± 16.01	0.0085*
	Post 6 months	57.22 ± 19.56	53.70 ± 18.80	52.11 ± 29.52	0.0989
	Post 12 months	60.29 ± 21.66	56.33 ± 21.05	58.26 ± 16.50	0.2820
	Post 24 months	70.04 ± 26.18	65.30 ± 18.48	58.56 ± 21.30	0.1646
Biochemical transient hypoparathyroidism	Yes	168 (26.5)	413 (38.3)	437 (57.1)	<0.0001
Clinical transient hypoparathyroidism	Yes	40 (6.3)	81 (7.5)	66 (8.6)	0.2628
Protracted hypoparathyroidism	Yes	14 (2.2)	16 (1.5)	8 (1.0)	0.2088
Permanent hypoparathyroidism	Yes	11 (1.7)	8 (0.7)	3 (0.4)	0.0228*

CND, central neck dissection; Pre, pre-operative; Post, post-operative; SD, standard deviation;

^*P < 0.05.