Abstract
Resistance to thyroid hormone syndrome (RTHS) is defined as increased thyroxine
and triiodothyronine associated with normal or increased thyrotropin. This is
usually due to a pathogenic variant of the gene coding for thyroid hormone
receptor B (THRB). THRB is a rare genetic disorder characterized by an altered
response of target tissue to the thyroid hormone action. Retrospective
cross-sectional observational study with diagnosis of RTHS evaluated in
secondary and tertiary hospitals for 6 years, from 2014 to 2020, in order to
describe variables including age, sex, anthropometric data, clinical and
biochemical characteristics of patients, who were divided according to age, in a
pediatric group from 0 to 14 years (index cases), and an adult group composed of
adult relatives of index cases. A molecular analysis of the THRB gene was
performed. The total retrospective cohort included 7 pediatric patients and 15
adults. We found 22 cases with a clear male predominance (14/22). Mean
age is 24.8 years old (22 days-70 years). Patients were referred because of
symptoms 18.2% (4/22), analysis results 22.7%
(5/22), or familial study 59.1% (13/22). About
31.8% (7/22) cases show goiter, 31.8% (7/22)
sympathetic symptoms and 13.6% (3/22) abnormalities in behavior.
In most cases, 77.3%, (17/22) show familial background of
thyroid abnormalities. It is important to remark that 18.2%
(4/22) relatives received previous incorrect treatments such as
thyroidectomy, because of wrong diagnosis. In conclusion, a better understanding
of RTHS, its prompt molecular diagnosis and genetic counseling, could avoid
unnecessary tests and inappropriate treatments.
Key words
resistance to thyroid hormone - thyroid receptor - symptoms - diagnosis - treatment
