Temporal trends of hyperthyroidism in GTD

There is some evidence that the clinical patterns and presentations of GTD have changed with the introduction of early pregnancy screening. We specifically explored temporal trends of hyperthyroidism in GTD.

A study by Hou et al. [6] compared 113 cases of hydatidiform mole during 1989–2006 with historical data from 1948 to 1975. They found significantly lower rates of GTD-related complications in the ‘modern’ cohort compared to the historical cohort, most likely due to earlier detection of GTD from routine use of first trimester ultrasonography and serum HCG testing [1, 6].

A Brazilian study [16] analysed medical records of women diagnosed with complete hydatidiform mole from 1988 to 2012. They assessed the prevalence of biochemical hyperthyroidism and trends over time. In contrast to the previous study by Hou et al., there was a significantly upward trend in the frequency of hyperthyroidism in women with GTD (0.69% in 1988–1992, 0.68% in 1998–2002 and 3.86% in 2008–2012). Notably, the latest rates (2008–2012) of biochemical hyperthyroidism at this centre was still lower than those described in the other studies. The significant increase in rates over time most likely reflects changes in management protocol for GTD. Prior to 2010, the centre only assessed patients for hyperthyroidism when patients presented with overt clinical hyperthyroidism, or when the uterus was markedly enlarged (> 16 cm). After 2010, however, routine screening for hyperthyroidism was conducted in all patients [16]. This example demonstrates that hyperthyroidism in GTD can be missed in the absence of routine biochemical screening.