Testicular dose and fertility in men following I¹³¹ therapy for thyroid cancer

Abstract

Radioiodine treatment for thyroid cancer may result in transient impairment of gonadal function. The radiation dose absorbed by the testis after a single ablative dose of radioiodine is well below that associated with permanent damage to germinal epithelium and the risk of infertility in these patients is minimal. Patients requiring multiple administrations for persistent or metastatic thyroid cancer may be at greater risk of gonadal damage although even in this group, we found no evidence of infertility.

Preparation with Recombinant Human Thyroid-Stimulating Hormone for Thyroid Remnant Ablation with 131I Is Associated with Lowered Radiotoxicity

“…Using MIRD (38), the estimated radiation in testes and ovaries would be 85 mGy and 140 mGy, respectively, when 3,700 MBq (100 mCi) of 131 I are administered during euthyroidism (as for the preparation with rhTSH). Specific studies on thyroidectomized patients during hypothyroidism suggest that the same activity would result in a testicular radiation of 86 mGy (39) to 120 mGy (40); the radiation in the ovaries would be much higher than estimated by MIRD (9), and an average radiation of 740 mGy would be obtained for the salivary glands (41). Interstudy comparison is inappropriate because of differences in the characteristics of the patients, in the preparation protocol, in the assessment techniques, and between examiners.…”

Management Guidelines for Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Taskforce

“…Ovarian damage from radioiodine therapy may result in menopause occurring approximately 1 year earlier than the general population, but this result was not associated with cumulative dose administered or the age at which the therapy was given (274). In men, radioiodine therapy may be associated with a temporary reduction in sperm counts and elevated serum follicle-stimulating hormone (FSH) levels (275,276). Higher cumulative doses (500-800 mCi) in men are associated with an increased risk of persistent elevation of serum FSH levels, but fertility and risks of miscarriage or congenital abnormalities in subsequent pregnancies are not changed with moderate radioiodine doses (approximately 200 mCi) (277,278).…”

Short-term Effects of Radioiodine Therapy on Auditory Function

“…The ability of the thyroid tissue to take up 131 I depends on a transport mechanism, namely, sodium iodine symporter (NIS). Physiologically, the main function of NIS is to transport iodide from the blood to the thyroid follicular cells along with sodium [20] . Na + /K -ATPase pump provides energy for this transport system [21] .…”

“…Hair cells rely on ionic gradients for receptor function. Stria vascularis is known to generate the positive potential for providing ionic gradient [20] . Fibrocytes of the stria vascularis contain Na + /K + /Cl -transporter that concentrates K + ions in the intracellular compartment.…”