People with HIV Have an Elevated Risk of Thyroid Dysfunction

By Liz Highleyman

Prior research has indicated that HIV positive people tend to experienced more endocrine problems than the general HIV negative population, though the underlying mechanisms are not fully understood.

According to a Letter to the Editor in the January 1, 2009 Journal of Acquired Immune Deficiency Syndromes, people with HIV appear to have a greater likelihood of disorders of the thyroid, a gland in the neck that regulates body metabolism. The include hypothyroidism (overactive thyroid), associated with fatigue and depression, and hyperthyroidism (underactive thyroid), associated with hyperactivity and anxiety.

Mark Nelson and colleagues from Chelsea and Westminster Hospital in London retrospectively analyzed medical records from 2437 HIV positive patients who underwent thyroid function testing between 1995 and 2006.

Hyperthyroidism was defined as a thyroid-stimulating hormone (TSH) level below the normal range (0.3-4.4 mU/L) and free thyroxine (T4) or free triiodothyronine above the normal range (free T4 9.0-26.0 mU/L; free triiodothyronine 2.23-5.3 pM). Conversely, hypothyroidism was defined as TSH above the normal range and T4 or free triiodothyronine below the normal range.

Results

54 patients (2.2%) exhibited abnormal thyroid function -- about twice as high as the rate in the HIV negative general population:

hypothyroidism: 28 patients (1.2%; 10.7 per 10,000 persons);

hyperthyroidism: 26 patients (1.0%; 3.4 per 10,000 persons);

40.0% of patients with hypothyroidism and 66.7% with hyperthyroidism had detectable thyroid antibodies.

After controlling for other factors such as age and CD4 cell count, use of protease inhibitors was a significant predictor of hypothyroidism.

Use of non-nucleoside reverse transcriptase inhibitors (NNRTIs), in particular efavirenz (Sustiva), was a significant predictor of hyperthyroidism.

Based on these findings, the study authors wrote, "We have revealed a higher than expected incidence of hypothyroidism in a large cohort of HIV-infected individuals although the retrospective nature of our cohort with an absence of a defined clinical protocol for thyroid function testing results in selection bias."

The high prevalence of thyroid antibodies, they suggested, might be related to immune reconstitution after starting antiretroviral therapy.

"Based on the previous extensive work in this area, and these data, we recommend routine screening of thyroid function in HIV-infected patients receiving HAART," they concluded.

Department of HIV Medicine, Chelsea and Westminster Hospital, Imperial College School of Medicine, London, UK.

1/23/09

Reference
M Nelson, T Powles, A Zeitlin, and others. Thyroid Dysfunction and Relationship to Antiretroviral Therapy in HIV-Positive Individuals in the HAART Era. Journal of Acquired Immune Deficiency Syndromes 50(1): 113-114. January 1, 2009.