Intermediate and long-term adverse effects of radioiodine therapy for differentiated thyroid carcinoma--a systematic review.

BACKGROUND: Treatment of differentiated thyroid carcinoma (DTC) often involves administration of radioactive iodine (I-131) for remnant ablation or adjuvant therapy. As DTC has favorable outcome and the incidence is increasing, concerns have been raised about the possible adverse effects of I-131 therapy. We systematically reviewed the literature to examine the risk of intermediate and long-term adverse effects of I-131 therapy in DTC patients. METHODS: Multiple electronic databases were searched up to November 2014 for English-language, controlled studies that reported on the risk of salivary gland dysfunction, lacrimal gland dysfunction, gonadal dysfunction, female reproductive outcomes or second primary malignancies (SPM) after I-131 exposure. The certainty of the evidence found was assessed using GRADE. RESULTS: In total, 37 articles met all inclusion criteria, no studies reporting on adverse effects after I-131 treatment focused solely on children. After exposure to I-131 for DTC, patients experienced significantly more frequently salivary gland dysfunction (prevalence range: 16-54%, moderate-level evidence), lacrimal gland dysfunction (prevalence: 11%, low-level evidence), transient male gonadal dysfunction (prevalence: 35-100%, high-level evidence), transient female gonadal dysfunction (prevalence: 28%, low-level evidence) and SPM (prevalence: 2.7-8.7%, moderate-level evidence) compared to unexposed patients. I-131 therapy seems to have no deleterious effects on female reproductive outcomes (very-low level evidence). The prevalence and severity of adverse effects were correlated to increasing cumulative I-131 activity. CONCLUSION: Treatment with I-131 for DTC may have significant adverse effects, which seem to be dose dependent. These adverse effects of treatment must be balanced when choosing for I-131 therapy in patients with DTC.

The effect of life-long thyroxine treatment and physical activity on bone mineral density in young adult women with congenital hypothyroidism.

OBJECTIVE: Normalization of plasma thyrotropin in T4-supplemented patients with thyroidal congenital hypothyroidism (CH) requires elevated plasma FT4-concentrations compared to patients with acquired thyroidal hypothyroidism. We investigated bone mineral density (BMD) in patients with CH. PATIENTS AND METHODS: BMD was measured in 14 adult women with thyroidal CH and nine age-matched female controls. RESULTS: There were no significant differences between patients and controls for femoral neck bone mineral content (BMC) (38.6 vs 37.6 g), BMD (0.98 vs 1.01 g/cm(2)), T-score (0.1 vs 0.3 SD) and z-score (0.1 vs 0.3 SD) and for spine BMC (63.1 vs 71.9 g). The differences in spine BMD (0.97 vs 1.09 g/cm(2)), T-score (-0.7 vs 0.4 SD) and z-score (-0.5 vs 0.6 SD) were significant (p = 0.025, p = 0.023, and p = 0.021, respectively). CONCLUSIONS: Although BMD in patients with CH was slightly lower compared to controls, all scores were within the reference range. This does not support the hypothesis that the upwards shifted plasma FT4-concentrations in patients treated for CH have a deleterious effect on BMD.