Clinical Hyperthyroidism in Chinese Patients with Stable HIV Disease

Sir—Only 2 cases of subclinical hyperthyroidism were found in the prevalence study of thyroid dysfunction by Beltran et al. [1]. We, however, found no cases of hypothyroidism and 9 cases of hyperthyroidism in a retrospective study of symptomatic thyroid disorders in patients attending an HIV/AIDS clinic until the end of 2003. Two more patients gave a history of thyrotoxicosis before diagnosis of HIV infection; they were excluded from the analysis. The incidence of clinical hyperthyroidism was 0.28 cases/100 patient-years (0.22 cases/100 patient-years for males and 0.55 cases/100 patient-years for females). The overall cross-sectional prevalence was 1.1% (0.9% for males and 2.0% for females). As shown in table 1, all 9 patients were Chinese, the ethnic group that constitutes 80% of our clinic's population. Weight loss was the most prominent feature of the clinical presentation, with a median decrease in body weight of 7.9% (range, 0%–13.9%) relative to body weight 6 months prior to the diagnosis of hyperthyroidism. Other classic thyrotoxic symptoms—for example, palpitation, tremors, and sweating—were also present in some patients but were not as marked. Goiter was only found in 4 patients. Demographic, clinical, and treatment characteristics of 9 Chinese patients with hyperthyroidism and HIV disease. Biochemical testing revealed that all patients had markedly suppressed levels of thyroid stimulating hormone, of which most were below the detection limit. All patients had grossly elevated serum levels of free thyroxine, except one who had elevated levels of free triiodothyronine. Unfortunately, because of the retrospective nature of the study, the etiology of hyperthyroidism could not be identified in patients for whom there was inadequate information. None of the patients had been investigated using thyroid scanning or tests for antithyrotrophin receptor autoantibodies. Of the 4 patients who tested positive for antimicrosomal antibodies, 2 patients had high titers (1600 IU/mL). Only 1 patient tested positive for antithyroglobulin antibodies. According to the available information, Graves disease was the cause of hyperthyroidism in 6 patients. The clinical and biochemical conditions of all 9 patients improved promptly after treatment with antithyroid drugs. At the time of diagnosis of hyperthyroidism, all patients except one were receiving HAART for a median duration of 57.6 months (range, 12.5–64.6 months). Also, most patients had experienced a substantial increase in CD4 count above the nadir (median, 223 cells/µL; range, 104–533 cells/µL), especially those patients with low baseline levels. However, in our study, only 3 patients were AIDS patients (patients 3, 5, and 7) and 1 never had symptoms of HIV infection (patient 9) (table 1), which is in contrast to another study [2] in which all cases of hyperthyroidism were found in AIDS patients. The occurrence of clinical hyperthyroidism in our patients could be coincidental or related to HAART. The higher prevalence of overt disease in our HIV cohort study, compared with studies reporting overt disease in 0.5% and 0.2% in general Chinese [3] and Japanese [4] populations, respectively, suggests an association. The fact that almost all patients were treated with HAART and experienced good immune recovery further supports this notion. Immune restoration due to HAART [5, 6] might have precipitated or hastened the manifestation of thyrotoxicosis in some individuals. Yet the delay between initiation of HAART and onset of clinical hyperthyroidism in our patients was much longer than that of another study, in which the median time until onset of Graves thyrotoxicosis was 20 months [2]. The severely abnormal biochemical profile and the marked weight loss might have been caused by severe disease or delayed diagnosis. In summary, we have found that overt hyperthyroidism is an uncommon but clinically important event in HIV-infected Chinese patients. Presentation mostly occurs in patients receiving HAART and is often delayed for years after treatment. Weight loss, which may be the only obvious feature, in a patient with otherwise stable HIV disease should prompt examination for the diagnosis or exclusion of hyperthyroidism. Awareness of the ever-increasing nonconventional complications in HIV/AIDS patients is essential for their timely diagnosis and management. We thank nursing colleagues at Integrated Treatment Centre for their help in data collection. Conflict of interest. All authors: No conflict.