Analysis of the incidence and influencing factors of hyponatremia before 131I treatment of differentiated thyroid carcinoma

Table 1 Clinical data of the patients with hyponatremia before ¹³¹I treatment

Patients	Age (yr)	Gender	Pre-operation sodium (mmol/L)	Pre-131I therapy sodium (mmol/L)	Potentially hyponatremia-inducing drugs	Potentially hyponatremia-inducing comorbidities
1	75	Male	138	134	Diuretic, ACEI	DM, adenocarcinoma of lung
2	71	Male	140	135	Diuretic, ARB	None
3	71	Male	140	133	None	None
4	64	Male	141	134	Diuretic	None
5	64	Male	141	135	None	None
6	64	Male	144	133	None	None
7	63	Male	136	134	Diuretic, ACEI	None
8	53	Male	140	135	None	DM
9	52	Male	138	135	None	DM, coronary heart disease
10	47	Male	144	135	None	None
11	45	Male	138	135	None	Adrenocortical hypofunction
12	38	Male	136	131	None	None
13	31	Male	136	128	None	DM
14	69	Female	140	129	None	RI, CHD, old cerebral infarction
15	49	Female	136	135	None	None
16	47	Female	142	135	None	None
17	42	Female	140	135	None	None
18	42	Female	140	134	None	None
19	41	Female	137	132	None	DM, diabetic nephropathy
20	35	Female	145	135	None	None
21	35	Female	138	134	None	None
22	33	Female	142	135	None	Chronic hepatitis B
23	32	Female	138	133	None	None

DM: Diabetes mellitus; ACEI: Angiotensin-converting enzyme inhibitor; ARB: Angiotensin receptor blocker; CHD: Coronary heart disease; RI: Renal insufficiency.

Table 2 Factors associated with pre-¹³¹I therapy serum sodium level

	Correlation r	P value
Age (yr)	0.087	0.009
TSH (mIU/L)	0.045	0.174
Tg (ng/mL)	-0.028	0.402
Urinary iodine (µg/L)	0.013	0.697
Pre-operation serum sodium (mmol/L)	0.395	0.001
Blood urea nitrogen (mmol/L)	0.028	0.401
eGFR (mL/min m2)	-0.073	0.027

Table 3 Baseline characteristics of the hyponatremia group and non-hyponatremia group before ¹³¹I treatment

Items	Hyponatremia group	Non-hyponatremia group	P value
Sex (n, %)			0.008
Male	13 (56.5)	270 (30.7)
Female	10 (43.5)	610 (69.3)
Age (yr)	50.5 ± 14.2	43.6 ± 12.7	0.01
Body mass index (kg/m2)	22.2 ± 3.3	23.1 ± 4.3	0.348
Systolic blood pressure (mmHg)	129.9 ± 21.1	124.5 ± 18.1	0.161
History of ACEI or ARB (n, %)			0.42
Yes	3 (13.1)	69 (7.8)
No	20 (86.9)	811 (2.2)
History of diuretics (n, %)			0.015
Yes	4 (17.4)	35 (4.1)
No	19 (82.6)	845 (95.9)
Distant metastasis (n, %)			0.014
Yes	6 (26.1)	77 (8.8)
No	17 (73.9)	803 (91.2)
Hemoglobin (g/L)	141.1 ± 19.5	144.2 ± 18.4	0.52
Fasting blood glucose (mmol/L)	5.2 (4.6, 7.2)	5.1 (4.8, 5.6)	0.267
Pre-operation serum sodium (mmol/L)	139.5 ± 2.6	141.3 ± 2.3	0.001
Pre-131I therapy serum sodium (mmol/L)	133.6 ± 1.9	140.6 ± 1.8	0.001
Serum potassium (mmol/L)	4.3 ± 0.3	4.2 ± 0.3	0.462
Serum calcium (mmol/L)	2.3 ± 0.1	2.2 ± 0.1	0.062
Blood urea nitrogen (mmol/L)	4.7 ± 2.1	3.8 ± 1.2	0.043
Serum creatinine (µmol/L)	78.7 ± 13.3	74.4 ± 16.4	0.271
Urinary iodine (µg/L)	83.1 (52.9, 100.3)	93.1 (54.5, 203.1)	0.037
Total protein (g/L)	77.1 ± 5.9	76.9 ± 4.4	0.865
Albumin (g/L)	46.6 ± 4.2	47.9 ± 2.8	0.155
Globulin (g/L)	30.5 ± 4.1	29.1 ± 3.7	0.077
eGFR (mL/min m2)	81.8 ± 11.4	88.8 ± 15.3	0.029
TSH (mIU/L)	99.5 ± 28.5	130.6 ± 59.4	0.001
FT3 (pmol/L)	2.8 ± 0.4	2.9 ± 0.6	0.594
FT4 (pmol/L)	2.1 ± 1.2	1.8 ± 1.2	0.27

DM: Diabetes mellitus; ACEI: Angiotensin-converting enzyme inhibitor; ARB: angiotensin receptor blocker.

Table 4 Logistic regression analysis of factors associated with hyponatremia development

Items	β	OR (95%CI)	P value
Gender (male)	-0.647	0.524 (0.203, 1.354)	0.182
Age (yr)	0.007	1.007 (0.965,1.050)	0.762
Distant metastasis (n)	1.193	3.296 (1.112, 9.770)	0.031
History of diuretics (n)	-1.212	0.298 (0.090,0.988)	0.048
TSH (mIU/L)	-0.009	0.991 (0.980,1.002)	0.101
Urinary iodine (µg/L)	-0.011	0.989 (0.98,0.998)	0.075
eGFR (mL/min m2)	-0.032	0.969 (0.934,1.005)	0.09
Pre-operation Na (mmol/L)	-0.271	0.763 (0.627, 0.928)	0.007
Blood urea nitrogen (mmol/L)	0.420	1.521 (1.094, 2.115)	0.013