Hypothyroidism associated with therapy for multi-drug resistant tuberculosis in Australia.

OBJECTIVE: Reports from resource-poor countries have associated thionamide- and para-aminosalicylate sodium (PAS)-based treatment of multidrug-resistant tuberculosis (MDR-TB) with the development of hypothyroidism. We aimed to identify predictors and assess the cumulative proportions of hypothyroidism in patients treated for MDR-TB with these agents in Australia.

DESIGN, SETTING AND PARTICIPANTS: Retrospective multi-centre study including MDR-TB patients from five academic centres covering TB services in Victoria, Australia. Patients were identified using each centre's pharmacy department and cross checked with the Victorian Tuberculosis Program. Hypothyroidism was categorised as subclinical if thyroid stimulating hormone (TSH) was elevated, and as overt if free thyroxine (fT4) was additionally reduced on two separate occasions.

MAIN OUTCOME MEASURE: Cumulative proportion of hypothyroidism (at 5 years from treatment initiation).

RESULTS: Of the 29 cases available for analysis, the cumulative proportion of hypothyroidism at 5 years was 37% (95% CI: 0-57.8%). Eight of the nine affected cases developed hypothyroidism within the first 12 months of treatment. Hypothyroidism was marginally (p=0.06) associated with higher prothionamide/PAS dosing and was reversible with cessation of the anti-tuberculosis medication.

CONCLUSIONS: Prothionamide/PAS treatment-associated hypothyroidism is common in MDR-TB patients in Australia, emphasising the importance of regular thyroid function monitoring during this treatment. Thyroid hormone replacement if initiated, may not need to be continued after MDR-TB treatment is completed. This article is protected by copyright. All rights reserved.