In order to assess the relation of thyroid function tests to human immunodeficiency virus (HIV) infection, we determined the levels of serum thyroid hormones, serum binding proteins [thyroxine-binding globulin (TBG), cortisol-binding globulin (CBG), and sex hormone-binding globulin (SHBG)], and serum tumor necrosis factor (TNF) in HIV-seropositive subjects at different clinical stages.
Thirty-seven HIV-seropositive patients were studied: 7 at stage II, 13 at stage III, and 17 at stage IV (eight ambulatory and nine hospitalized) according to the Centers for Disease Control's criteria.
As compared with stage II and stage III patients, stage IV patients had significantly higher mean TBG and total thyroxine (TT4) values, similar and normal total triiodothyronine (TT3) levels, and similar and abnormally low reverse triiodothyronine (rT3) concentrations. However, stage IV hospitalized patients had significantly lower TT3 values than stage IV ambulatory patients. In contrast to TBG, mean levels of CBG and SHBG were comparable in the three groups and within normal limits. For the whole population of HIV patients, there was a highly significant correlation between the CD4 lymphocyte count and TBG (r = -0.529, p less than 0.001) but not with CBG and SHBG levels. Finally, TNF values higher than 10 pg/mL were detected in six of the 17 stage IV patients and in only one of the 13 stage III patients (p = 0.059); elevated TNF levels correlated with a lower CD4 count (p less than 0.01) but not with serum TBG levels.
The progression of HIV infection is associated with an elevation of serum TNF and TBG, but not of CBG or SHBG. HIV-infected patients have an unexpectedly normal TT3-low rT3 state.