Do general practitioners use thyroid stimulating hormone assay for opportunistic screening?

AIM

The presenting features of early thyroid disease can be subtle and non-specific; consequently, general practitioners (GPs) have a low threshold for ordering thyroid function tests (TFTs). This study examined the use and results of TFTs by GPs in a 1-year period in a population-based sample of adults without known thyroid disease enrolled in general practice.

METHOD

This record linkage study analysed the use of TFTs over a 12-month period from laboratory data, which were linked to patient's GP records from two large urban New Zealand general practices with a total registered population of 21,290 patients. Outcomes were analysed by age and gender.

RESULTS

One in six adult patients visiting their GP in a 12-month period had a thyroid stimulating hormone (TSH) test, whilst only 1 in 20 had a free thyroxine (FT4) test. 7.0% had an elevated TSH concentration and 1.0% had a low TSH concentration, most with subclinical disease. Rate of testing was higher in females compared with males.

CONCLUSION

This study suggests that general practitioners are opportunistically screening with TSH alone to find new cases of thyroid disease.