Effectiveness of radioactive iodine (131I) in the treatment of Graves' disease: single center experience in Assiut University hospital

Abstract

To evaluate the effectiveness of radioactive iodine (¹³¹I) therapy in patients with Graves' disease (GD) in Assiut University Hospital. We retrospectively evaluated two hundred and seven patients with GD, after their therapy with ¹³¹I. Before therapy all the included patients underwent neck ultrasound, hormonal assay and ^99mTechnetium-pertechntate (^99mTc) thyroid scintigraphy to evaluate percentage uptake of the thyroid gland, after therapy all patients followed up clinically and laboratory every 3 months for at least one year to detect outcome; where euthyroid or hypothyroid status denotes successful therapy. Successful outcome obtained in 165/207 patients representing 79.7% of the study population while in the remaining 42 (20.3%) patients a second dose was required. In Univariate analysis only dose of ¹³¹I and previous thyroid surgery are the important factors (P value = 0.003 and 0.001 respectively). We concluded that ¹³¹I therapy is highly effective and cost-effective method for treatment of GD, higher doses are associated with higher success rate.

Keywords: Graves’ disease; radioactive iodine (131I) therapy.

Figure 1

Thyroid uptake, Patient’s first thyroid scan (A) showed diffuse goiter and a 42.6% ^99mTc-pertechnetate uptake. This was followed by administration of a 555 MBq (15 mCi) of ¹³¹I. Subsequent follow up showed persistent suppression of TSH and elevation of FT3 and FT4, and ATDs was reintroduced. 6 months after ¹³¹I therapy, Patient’s second thyroid scan (B) showed a 6.7% ^99mTc-pertechnetate uptake. Consequently, a second dose of 370 MBq (10 mCi) ¹³¹I was administrated. Three months later, laboratory workup showed overt hypothyroidism (TSH: 75 uIU/mL, FT3: 1.04 pg/mL, and FT4: 0.35 ng/dL), and levothyroxine replacement therapy was initiated.

Figure 2

Outcome of ¹³¹I treatment in 207 hyperthryoid patients.

Figure 3

The pattern of changes in serum concentrations of thyroid function studies following ¹³¹I therapy. Comparison of the mean serum levels of TSH (left), FT3 (middle), and FT4 (right) at baseline, 3 months and 6 months after ¹³¹I therapy between those who successfully treated with a single dose of ¹³¹I and those who experienced ¹³¹I treatment failure.