Researchers have called for a review of guidelines after finding a wide range of practice between clinicians regarding treatment of infants with borderline TSH elevation identified after newborn thyroid function screening.

According to an online survey of members of the Australasian Paediatric Endocrinologist Group (APEG), the frequency of follow-up and the levels of thyroid hormone at which treatment is commenced may differ between clinicians.

Recently updated European guidelines recommend treatment should be started at confirmatory serum TSH concentrations >20 mU/L while US guidelines recommend treatment for ‘persistent basal TSH’ >10 mU/L after the first 2 weeks of age.

The study, published in the Journal of Paediatrics and Child Health [link here], said current Australian guidelines do not specify a level of elevated serum TSH at which treatment should begin.

In the survey, APEG members were presented with four case scenarios, three of which qualified for treatment with thyroxine under the guidelines.

Of the 42 respondents, only 7% would treat the infant with an initial TSH on blood spot of 8.3 mU/L and borderline confirmatory serum TSH of 8.7 mU/L.

However the proportion of clinicians who would treat the three infants with elevated confirmatory serum TSH levels of 21.4 mU/L, 24.3 mU/L and 44.7 mU/L varied at 59%, 94% and 100% respectively.

“For children with elevated TSH levels (case 4: 44.7 mIU/L at confirmatory serum), over three quarters (77%) of clinicians would perform a thyroid 99mT or 123I scan, and 38% would perform a thyroid ultrasound.”

“There was a range in responses as to how soon physicians recheck TFTs after initiating treatment with thyroxine; 26% would check 5–7 days after, 12% after 8–10 days, 40% after 11–14 days and 14% more than 14 days after,” the study said.

“For children with a normally sited thyroid gland who had not required increasing doses of thyroxine with growth, 35% of respondents would trial thyroxine cessation at 2 years of age, and 55% would trial stopping treatment at 3 years of age.”

”The authors said that in children with thyroid abnormalities, prompt initiation of treatment that normalises thyroid levels has been shown to result in mostly normal neurocognitive outcomes.

They recommended that AAP and APEG guidelines should be reviewed and expanded to include new evidence, particularly on the cognitive outcomes of children with mildly elevated TSH levels.

“This will ensure up-to-date evidence-based guidelines are available to ensure consistent practice across clinicians,” they concluded.