Impaired essential fatty acid metabolism in latent tetany.

Because of the biochemical role of magnesium in the metabolism of polyunsaturated fatty acids, we measured the levels of polyunsaturated fatty acids in the plasma phospholipids of 40 patients with latent tetany (LT). The level of linoleic acid (18:2 n-6) was 25% higher in patients than in controls (p less than 0.001). In contrast, dihomogamma linoleic acid (20:3 n-6) was 34% lower, arachidonic acid (20:4 n-6) was 14% lower than in controls (p less than 0.01) and the ultrapolyunsaturates, 22:4 n-6 and 22:5 n-6, were reduced by 27 and 53%, respectively (p less than 0.001). Linolenic acid (18:3 n-3) was not significantly different from control levels, but its metabolite, eicosapentaenoic acid (20:5 n-3) was reduced by 43% (p less than 0.05). Since the levels of plasma phospholipid fatty acids are a reflection of hepatic metabolism, these findings suggest that patients with LT have impaired desaturation of 18:2 n-6 and possibly 18:3 n-3. The desaturase enzyme is Mg dependent, and impaired desaturation has been demonstrated in animals rendered Mg deficient. Possible consequences of this impairment in essential fatty acid (EFA) metabolism are an increase in membrane viscosity and a distortion in the availability of fatty acid precursors for prostaglandin synthesis. Either of these abnormalities may contribute to the pathogenesis of illness associated with LT.