Effectiveness of 131-I Therapy in Graves’ Disease Patients

the words Graves Disease largely typed into a book with a pair of reading glasses resting on topIn China, researchers studied the effectiveness of radioactive iodine therapy—referred to as 131-I therapy—in patients with Graves’ disease.  They were looking to improve its one-time curative ratio.

Their study is published in the January 2012 issue of Nuclear Medicine Communications; the article is “Analysis of 131I therapy and correlation factors of Graves’ disease patients:  a 4-year retrospective study.”

There were 766 patients in the study—529 women (range 14-75 years old; mean 40.22±13.34 years) and 237 men (range 12-77 years; mean 40.98±13.12 years).  Overall, the age range of the patients was 12-77 years; the mean was 40.46±13.12 years.

Before the patients received the first 131-I therapy, they underwent several tests:

  • the maximal radioactive uptake of thyroid (RAIUmax)
  • the effective half-life (EHL)
  • the ultrasound of thyroid to calculate its weight
  • thyroid imaging with single-photon emission computed tomography and serum-free triiodothyronine (FT3)
  • free thyroxine (FT4)
  • sensitive thyroid-stimulating hormone (sTSH)
  • anti-thyrotrophin receptor antibody (TRAb)
  • thyroid-stimulating immunoglobulin
  • thyroflobulin antibody (TgAb)
  • anti-thyroid microsome antibody (TMAb)

For every patient, the 131-I dosage was determined, and then they all took it once orally.  The 131-I dosage range was 74-592 MBq (22.63±100.64).

At 1, 3, 6, and 12 months following 131-I therapy, each patient underwent clinical and laboratory assessment.  They were grouped into two divisions:  the clinically recovered group (symptoms and signs disappeared, free thyroid hormone levels within or below the normal range, and sTSH within of above normal range) and the clinically unhealed group (symptoms and signs disappeared partially, free thyroid hormone levels still above the normal range [or within normal range for some time but then increased again], and sTSH was always below the normal range).

The researchers analyzed the data with the unpaired t-test, the independent samples t-test, and Chi-test, logistic regression, and Pearson bivariate correlation.

The researchers saw a one-time curative rate of 78.7% (this include euthryoidism and hypothyroidism.

They noted that there were several factors that influence the effectiveness of 131-I therapy; these included age, EHL, TRAb, RAIUmas, and TgAb.

The protecting factors were RAIUmax and EHL. The risk factors were TRAb, TgAb, and age.

TRAb also influenced the one-time curative ratio between patients with negative and positive TRAb; that ratio was higher in men (2.836 times) than in women (1.438 times).

The researchers concluded that 131-I therapy is effective for patients with Graves’ disease, noting that the higher the RAIUmax and/or the longer the EHL, the higher the possibility of a one-time curative effect.  Additionally, older patients or patients with a positive TRAb and/or TgAb have a lower possibility of a one-time cure.  Finally, women with a positive TRAb should be given an increased 131-I dose; this will improve the curative effect.

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