Lower serum magnesium level after exposure to cold in women with primary Raynaud's phenomenon

Abstract

Serum levels of magnesium (s-Mg), calcium (s-Ca), potassium (s-K) and sodium (s-Na) were measured in 80 women with primary Raynaud's phenomenon (RP) and in 24 age-matched female controls recruited from a population survey. The blood samples were taken after a 40-min standardized whole body cooling test. The mean s-Mg level in the group with RP was significantly lower than in the controls (0.81 +/- 0.05 vs. 0.86 +/- 0.07 mmol l-1, P less than 0.05). One year later, 66 members of the RP group and 22 members of the control group were investigated further, but without any exposure to cold. No differences in mean s-Mg values were found between the groups. The mean s-Mg level was significantly higher in the blood samples taken later without cold exposure than at the initial examinations after exposure to cold in the RP group, but not in the controls. The s-Mg level was lower after exposure to cold in 82% of the women with RP, compared to 45% of the controls (P less than 0.001). No differences in the other electrolytes were found. It is concluded that exposure to cold under standardized conditions may decrease the s-Mg level in women with primary RP. Further studies of the role of magnesium in patients with RP are required.