Thyroid and Parathyroid

These drugs also can cross the placenta, inhibiting fetal thyroid function, and they are
excreted in breast milk. Side effects of treatment include skin rashes (1 percent),
fever, peripheral neuritis, polyarteritis, granulocytopenia (which is reversible on
discontinuing treatment), and, rarely, agranulocytosis (1:250). In rare instances,
aplastic anemia, which has a poor prognosis, has been documented. Patients should be
monitored for these possible complications and warned to stop medication and seek
. medical advice should they develop a sore throat or fever
Standard medical treatment is to start the patient on 100 to 300 mg propylthiouracil
three times daily, or 10 to 30 mg methimazole, initially three times daily and then
once daily, or 40 mg carbimazole daily. Beta blockers are often used initially, before
the diagnosis is made, to treat tachycardia and may be added for symptomatic relief.
Patients are observed regularly on an outpatient basis, and the dose of antithyroid
medication is titrated as needed in accordance with TSH and T4levels. Most patients
have improved symptoms in 2 weeks and become euthyroid in about 6 weeks. The
regimen described here is in wide use, though some physicians add thyroxine 0.05 to
0.10 mg to prevent hypothyroidism (the blocking/replacement regime). The length of
treatment with antithyroid drugs is controversial. For patients with small, diffusely
enlarged glands or larger glands that decrease in size in response to treatment with
antithyroid medication, the relapse rate after treatment for 12 to 18 months is about 50
percent. Patients with larger diffuse glands or toxic nodular goiter develop recurrent
hyperthyroidism when the antithyroid medication is discontinued, and hence
. definitive treatment with thyroidectomy or radioiodine therapy is indicated
( Radioactive Iodine Therapy (131I
Most patients in the United States undergo treatment with radioiodine. The major
advantages of this form of treatment are the avoidance of a surgical procedure and the
concomitant risks of recurrent laryngeal nerve damage and hypoparathyroidism,
reduced overall treatment costs, and ease of treatment. The major disadvantage is the
high incidence of hypothyroidism requiring lifelong thyroxine replacement therapy,
the slower correction of the hyperthyroidism, and a higher relapse rate after initial
treatment, necessitating further therapy. Radioiodine therapy also has more of an
. adverse effect on ophthalmopathy than does thyroidectomy
Patients most suitable for 131I therapy are those with small or moderate- sized
goiters, those who have relapsed after medical or surgical therapy, and those in whom
antithyroid drugs or surgery are contraindicated. Younger patients (under 35 years of
age) usually are treated with thyroidectomy, and older patients are treated with 131I.
Radioiodine therapy is contraindicated in women who are pregnant or breast-feeding.
Relative contraindications are ophthalmopathy (in which progression of eye signs has
been documented), patients with isolated thyroid nodules or toxic nodular goiters, and
young age (i.e., especially children and adolescents). Although there is no evidence of
long-term problems with infertility or increased incidence of cancer in children who
have been treated with 131I, most specialists are reluctant to treat children in this
manner and suggest thyroidectomy (usually near-total) for this age group. Children
treated with radioiodine for Graves' disease have an increased risk of developing
. hyperparathyroidism
Patients should be euthyroid before 131I therapy and should stop all antithyroid drugs
for 2 to 3 weeks before treatment in order to allow for adequate uptake into the