IMPAIRED PARATHYROID-HORMONE RELEASE IN HUMAN-IMMUNODEFICIENCY-VIRUS INFECTION

Patients with human immunodeficiency virus type 1 (HIV-1) seropositivi ty exhibited significantly lower intact serum parathyroid hormone (PTH ) values (mean, 13.6 ng/liter; n = 44) than healthy controls (mean, 38 .1 ng/liter; p < 0.001; n = 50). The reduction was greater among patie nts with no or mild immunodeficiency (>400 x 10(6) CD4(+) lymphocytes/ ml blood; n = 22) than in those with severe immunodeficiency (<200 x 1 0(6) CD4(+) lymphocytes/ml blood; n 22; p = 0.03), although total seru m calcium was normal in all groups. Patients with severe immunodeficie ncy demonstrated an inverse correlation between total serum calcium an d serum PTH (r(2) = 0.367; p < 0.01), which was also present in health y controls (r(2) = 0.482; p;= 0.001), but not among the seropositive p atients with no or mild immunodeficiency (r(2) = 0.017; p = 0.58). Par athyroid cells express a protein recognized by antibodies directed aga inst CD4, the HIV-1 receptor. This implies that these cells may be dir ectly infected with HIV-1 and also interact with circulating autoantib odies against CD4, thus resulting in impaired PTH release.