Warning over thyroid hormone treatment of pregnant women
Use of thyroid hormones in women with hypothyroidism who become pregnant has come under the spotlight following a study published last week
(JAMA 2004;292:691).
Researchers have concluded that high levels of thyroid hormone in pregnant
women can increase the risk of miscarriage or result in a lower birth
weight for their infants. They came to their conclusions after investigating
the effects of excess thyroid hormone among members of a family with
mutations in the thyroid-hormone receptor gene. Affected people have
a resistance to thyroid hormone and so compensate with increased thyroid
gland activity. By comparing pregnancy outcomes in affected and unaffected
members of the family, the researchers were able to show that high serum
levels of thyroid hormone were associated with a higher rate of miscarriage.
Furthermore, offspring who inherited the genetic mutation and so were
resistant to the hormone had a higher birth weight than their unaffected
siblings.
“Given the established importance of providing thyroid hormone
to even mildly hypothyroid pregnant women, it is important to recognise
that
over-replacement appears to be equally detrimental,” they conclude. |
The
Pharmaceutical Journal
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