The influence of biological sex on the biodistribution of I-131 in mice

• Background: The thyroid is both a risk and target organ in radionuclide therapy. The gland takes up iodine to synthesize thyroidal hormones which are important for various cellular mechanisms throughout the body. 131I is used in nuclear medicine, but hazard exposure can also occur from fallout of nuclear accidents. Physiological differences between the sexes constitute intrinsic variables that are thought to impact the biodistribution of 131I. Aim: The purpose of this study was to assess potential difference between the sexes concerning 131I biodistribution in mice. Methods: In total, 70 C57BL/6N mice (35 males and 35 females) were used in the experiments (n=5/group). Mice were injected intravenously (at 8 am) with 165−175 kBq 131I, prepared in physiological saline, and killed after 1h to 7d following injection. Various tissue samples were collected, weighed, and subjected to gamma counter measurement to determine 131I activity concentration. Results: The results demonstrated clear differences in 131I biodistribution between male and female mice, notably in the kidneys and salivary glands. Statistically significant differences were found for the majority of tissues and time points. Although maximum uptake in the thyroid was similar for both sexes, the decrease of activity concentration after 18h was distinctly slower in females showing statistical significance. Conclusion: Experiments demonstrated that 131I biodistribution differs between the sexes, which would translate to differences in absorbed dose. The extent of difference is tissue-dependent, with markedly different biodistribution in certain tissues. The results advocate that sex should be considered as a variable in biodistribution studies and dose calculations.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Radiologi och bildbehandling (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Radiology, Nuclear Medicine and Medical Imaging (hsv//eng)

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