Table 2. Total sodium concentrations in healthy controls and subjects grouped by clinical status at 15 years.

	Healthy controls (n=34)	Patients with CIS (n=18)	Patients with MS
			All MS (n=78)	RRMS (n=65)	SPMS (n=13)
Brain parenchymal	0.768	0.767	0.747*, †	0.751	0.731¶
fraction	(0.009)	(0.008)	(0.028)	(0.018)	(0.028)
Grey matter	0.458	0.453	0.445*, ‡	0.447	0.438¶
fraction	(0.009)	(0.006)	(0.014)	(0.012)	(0.014)
White matter	0.310	0.314	0.302*, †	0.303	0.293 ¶
fraction	(0.011)	(0.010)	(0.016)	(0.016)	(0.016)
T2 lesion volume, ml			11.08 (12.00)	9.81 (11.60)	17.97¶ (12.28)
T1 lesion volume, ml			2.54 (3.52)	1.90 (2.91)	5.87¶ (4.53)
23 Na MRI
Cortical grey matter	40.63 mM (2.33)	40.68 mM (1.74)	42.82 mM* (3.53)	42.30 mM (3.29)	45.45 mM** (3.69)
Deep grey matter	34.83 mM (2.79)	36.13 mM (1.69)	36.69 mM§ (3.74)	36.14 mM (3.47)	39.47 mM** (3.98)
Normal-appearing white matter	32.03 mM (3.44)	32.92 mM (2.43)	34.85 mM§ (4.05)	34.43 mM (3.95)	36.95 mM (4.04)
White matter lesions
All T2-hyperintense lesions			45.58 mM (8.53)	44.27 mM (8.27)	51.99 mM¶ (6.92)
T1-isointense lesions			43.93 mM (5.83)	42.87 mM (7.04)	49.30 mM¶ (5.83)
T1-hypointense lesions			52.08 mM (7.43)	51.02 mM (11.56)	57.45 mM (7.43)

All data presented as mean (SD).

^*P<0.01 compared with healthy controls.

^†P<0.01 compared with CIS;

^‡P<0.05 compared with CIS.

^§P<0.05 compared with healthy controls.

^¶P<0.01 compared with RRMS.

^**P<0.05 compared with RRMS.

CIS, clinically isolated syndrome; MS, multiple sclerosis; RRMS, relapsing-remitting MS; SPMS, secondary progressive MS.