Focus on radioiodine-131 biokinetics: the influence of methylprednisolone on intratherapeutic effective half-life of 131I during radioiodine therapy of Graves’ disease

Abstract

Aim Radioiodine therapy (RIT) may trigger the development of Graves’ ophthalmopathy (GO) or exacerbate pre-existing subclinical GO. Therefore, glucocorticoid administration is recommended for patients with pre-existing GO. Aim of this study was to analyze the influence of glucocorticoid therapy with methylprednisolone on intratherapeutic effective half-life (EHL) of radioiodine-131 in patients with Graves’ disease (GD) as recent studies showed an effect for prednisolone. Methods In a retrospective study, 264 patients with GD who underwent RIT without any additional antithyroid medication were evaluated. Intrathyroidal EHL was determined pre- and intratherapeutically. Patients with co-existing GO (n = 43) received methylprednisolone according to a fixed scheme starting 1 day prior to RIT, patients without GO (n = 221) did not receive any protective glucocorticoid medication. The ratios of EHL during RIT and during radioiodine uptake test (RIUT) were compared. Results Patients receiving methylprednisolone showed a slight decrease of the mean EHL from 5.63 d (RIUT) to 5.39 d (RIT) (p > 0.05). A comparable result was obtained in patients without glucocorticoids (5.71 d (RIUT) to 5.47 d (RIT); p > 0.05). The ratios of the EHL between RIT and RIUT failed to show a significant difference between the two groups. EHL is therefore not significantly influenced by an additional protective treatment with methylprednisolone. Conclusions In the present study a decreased intrathyroidal EHL under glucocorticoid medication with methylprednisolone could not be detected. Therefore, co-medication with methylprednisolone in patients with GO may be preferred to avoid an intratherapeutic decrease of EHL by accompanying protective glucocorticoides.

Relative Adrenocortical Insufficiency Following Radioactive Iodine Therapy for Graves’ Disease: A Report of Two Cases

“…16 Third, the intra-therapeutic 131 I uptake and effective half-life (EHL) for patients were not evaluated, which may influence therapeutic outcome or trigger potential side effects. 23,24 In summary, based on these two cases, we propose that the adrenocortical function of patients with severe thyrotoxicosis be evaluated around 131 I administration for. Determination of the basal serum cortisol level is an optional screening test in testing-limited institutions.…”

“…22 Actually, factors like inaccurate dose due to potential changes of pre-to intra-therapeutically biokinetics of 131 I may induce side effects such as thyroid swelling, sialadenitis, or immune response. [23][24][25] RAI therapy may even trigger rare complications like thyroid storm and heart block. 26 Combined with the aforementioned points, one may reasonably conceive that some patients would suffer symptoms of cortisol deficiency in the post-RAI period due to the short-term worsening of hyperthyroidism or the possible immune interaction.…”

“…29 Methylprednisolone may be preferred to prednisolone to obtain a stable intra-therapeutic EHL of 131 I. 23 If suspected adrenal crisis does occur following RAI, we suggest performing random serum cortisol and plasma ACTH measurement immediately and giving intravenous hydrocortisone succinate and fluid resuscitation. The dose and course depend on individual varied conditions.…”

The influence of thyroid hormone medication on intra-therapeutic half-life of 131I during radioiodine therapy of solitary toxic thyroid nodules

“…In several countries, the pre-therapeutic determination of the effective half-life is a non-optional requirement. It directly influences the absorbed radiation dose to the thyroid and therefore the success of RIT 10 , 11 , 15 , 16 . The emitted beta radiation leads to ionisation resulting in cell death.…”

Retrospective Analysis of the Development of Human Thyroglobulin during Pregnancy in Patients with Treated Non-Recurrent Differentiated Thyroid Cancer

“…Radioiodine therapy (RIT) is a well-established integral part of therapy in patients with benign and malignant thyroid diseases [ 1 , 2 , 3 , 4 , 5 ]. Based on the German Guideline [ 1 ], all differentiated thyroid cancers (DTC) except non-metastatic papillary microcarcinoma are usually treated with thyroidectomy and, depending on the tumor stage, at least one RIT [ 6 ].…”