Download Management of Hyperthyoidism Iraj Nabipour Bushehr University of

Management of Hyperthyoidism
Iraj Nabipour
Bushehr University of Medical Sciences
Hyperthyroidism
 Hyperthyroidism is
predominantly a
disorder in women.
 prevalence of
approximately 0.6%
among women.
 Graves' disease is the
most common cause
of hyperthyroidism
Graves’disease
 Graves' disease is an autoimmune disorder caused
by an antibody that acts as an agonist on the
thyrotropin receptor.
 Spontaneous remission in 30%
 Ophthalmopathy in one third of patients
Hyperthyroidism
 iodine deficiency,
 the prevalence of toxic adenoma and multinodular
goiter increases with age,
 more common than Graves' disease in older
persons
Toxic adenoma and
multinodular goiter
 cause autonomous, unregulated synthesis of
thyroid hormone.
 mutation in the thyrotropin receptor gene
 not associated with ophthalmopathy
 not resolve spontaneously
 Radioiodine therapy and surgery
Untreated hyperthyroidism
 atrial fibrillation,
cardiomyopathy,
and congestive
heart failure.
 thyroid storm has a
mortality of 20 to
50%.
 osteoporosis and
fracture.
Treatment options
 Antithyroid drugs (USA)
 Radioiodine therapy (Europe and Japan)
 Surgery
 a trend towards primary pharmacological
treatment
Outcomes for treatment
 90% patient
satisfaction,
 no difference in
time to
euthyroidism,
 and similar rates of
sick leave for all
three.
 long-term quality
of life to be similar
Reasons for Antithyroid
drugs
 before radioiodine administration and usually before
surgery, several weeks of treatment with an antithyroid
drug is administered to achieve a euthyroid state.
 in Graves' hyperthyroidism for 1 to 2 years, or longer for
remission.
 Remission of hyperthyroidism is not expected in toxic
adenoma or toxic multinodular goiter.
Mechanisms of action
 inhibit organification of iodide and coupling
of iodothyronines, and hence synthesis of
thyroid hormones.
 Propylthiouracil also inhibits peripheral
mono-deiodination of T4 to T3
 immunosuppressive.
Methimazole vs PTU
 Compliance is better with methimazole
(once daily)
 propylthiouracil (two or three times a day)
 methimazole is now the starting drug of
choice
 Methimazole is more effective than
propylthiouracil at rapid restoration of
euthyroidism
Starting dose
 starting dose of methimazole is 10–20 mg per day.
The equivalent dose of propylthiouracil is 50–100
mg twice daily
 most patients have a normalised serum
concentration of free T4 after 8–12 weeks.
 Thyroid function should be assessed initially
every 4–6 weeks
Follow-up
 Serum TSH might remain suppressed for weeks or
months after free T4 has normalised,
 a rise in serum TSH above the reference range
does necessitate a dose reduction.
 Once methimazole dose has been reduced to
maintenance levels of 5–10 mg per day,
biochemical variables can be monitored less
frequently (every 2–3 months).
Remission
 Treatment duration longer than 18 months is not
associated with improved rates of remission.
 rate of remission of Graves' hyperthyroidism is
roughly 30%.
Predict low likelihood of
remission
 more severe biochemical disease,
 male
 young age (<40 years)
 high concentrations of TSHR antibodies
 large goitre
 smoking
PTU
 Should no longer be used as first line treatment in
adults or children, unless
 the patient is in the first trimester of pregnancy
 reports side-effects from methimazole,
 if radioiodine or surgery is not an option,
 thyroid storm
β blockers
 improves tremor, palpitation, and anxiety
 Propranolol, metoprolol, nadolol, and
atenolol are all effective.
 a long-acting drug is preferable and can be
continued until euthyroidism has been
restored by antithyroid drugs
Radioiodine (131I)
 is similarly processed,
 its beta emissions result in tissue necrosis,
 effectively ablating functional thyroid
tissue over the course of 6 to 18 weeks or
more.
High-risk patients
 with antithyroid drugs for several
weeks before radioiodine
 elderly persons,
 underlying cardiovascular disease
 severe hyperthyroid symptoms
 concentrations of thyroid hormone
two to three times as high as the upper limit of the
normal range.
Pretreatment with an
antithyroid drug
 may increase the risk of treatment failure with the initial
radioiodine dose
 propylthiouracil but not methimazole.
 Antithyroid drugs are discontinued 2 to 3 days before the
administration of radioiodine.
Radioiodine
 orally as a single dose of 131I-labeled
sodium iodide (Na131I) in liquid or capsule
form.
 three fixed doses in amounts based on gland
size as determined by palpation (5, 10, or 15
mCi)
Radioiodine
 The cell necrosis induced by radioiodine occurs
gradually, and an interval of 6 to 18 weeks or
longer must elapse before a hypothyroid or
euthyroid state is achieved.
 During that interval, hyperthyroidism may
transiently worsen.
 If the patient was pretreated with antithyroid
drugs, they may be resumed 3 to 7 days after
radioiodine administration
Monitoring
 at intervals of 4 to 6 weeks.
 When thyroid function has normalized, treatment
with beta-blockers and antithyroid drugs is
stopped and levothyroxine is administered as
indicated
 Suppression of serum thyrotropin may be
prolonged after successful treatment; therefore
measurement of free T4 and T3 is essential for
several months after radioiodine therapy.
Outcome
If sufficient
radioiodine is
administered,
hypothyroidism
develops in 80 to
90% of patients with
Graves' disease; 14%
of patients require
additional treatment.
Contraindications
 Absolute contraindications to radioiodine treatment are




pregnancy, lactation, and an inability to comply with
radiation safety regulations.
Radioiodine is considered safe for use in women of
childbearing age and in older children.
Moderately severe ophthalmopathy
Concurrent administration of glucocorticoids mitigates
exacerbations, at least in patients with mild
ophthalmopathy.
Patients who are allergic to iodinated radiocontrast agents
are usually not allergic to radioiodine.
Complications
Radiation thyroiditis
 In most studies, radioiodine has not been
associated with an increased risk of cancer.
 at increased risk for death from cardiovascular
disease primarily in the first year after treatment.

Relative indications for
surgery
 large goitre (suspicion or
diagnosis of coexisting
thyroid cancer are
absolute indications),
pregnancy (if drug sideeffects are serious) or
desire for pregnancy, and
pronounced
ophthalmopathy.
 Relapse after a course of
antithyroid drugs is also a
relative indication.
Relative indications for
surgery
 Total thyroidectomy is the
preferred surgical
approach in view of the
relapse rate after partial
thyroidectomy
 In experienced hands, the
rates of permanent
hypoparathyroidism and
recurrent laryngeal nerve
damage are less than 2%
and 1%, respectively.
Recommendations
 Radioiodine, antithyroid drugs, and surgery are all reasonable
 Pretreatment with antithyroid drugs should be considered in elderly
persons and in patients with underlying cardiovascular disease, severe
hyperthyroid symptoms, or thyroid hormone concentrations that are
two to three times the upper limit of the normal range.
 Surgery, rather than radioiodine therapy, is recommended for patients
with active, moderately severe Graves' ophthalmopathy.
 Concurrent use of glucocorticoids should be considered in those with
active, mild ophthalmopathy and in smokers.
 Patients should be returned to the euthyroid state with antithyroid
drugs before surgery to avoid thyroid storm.