Endocrine dysfunction after total body irradiation and bone marrow transplantation

Area of Science:

• Endocrinology
• Hematology
• Oncology

Background:

• Endocrine glands often appear morphologically resistant to irradiation.
• Sensitive assays now detect subtle functional changes in endocrine parameters post-irradiation.
• Total body irradiation (TBI) followed by bone marrow transplantation (BMT) necessitates understanding endocrine system responses.

Purpose of the Study:

• To serially monitor endocrine parameter changes in patients undergoing TBI and BMT.
• To investigate the temporal dynamics of endocrine system reactions to TBI and BMT conditioning.
• To identify long-term endocrine sequelae, including gonadal insufficiency and hypothyroidism.

Main Methods:

• Serial endocrine studies were conducted on 16 patients receiving TBI and BMT.
• Pretransplant conditioning involved single-dose irradiation and high-dose chemotherapy.
• Hormonal levels including ACTH, cortisol, thyroid hormones, testosterone, and luteotropic hormone were measured.

Main Results:

• Early changes observed in the pituitary-adrenal cortex axis (ACTH, cortisol).
• A transient "low-T3-syndrome" and increased thyroxine indicated extreme stress.
• Primary gonadal insufficiency was evident from low testosterone and luteotropic hormone levels.
• Most hormonal levels normalized post-transplant, except for sexual steroids, indicating persistent gonadal insufficiency.
• Subclinical hypothyroidism was noted in some patients as a potential late effect.

Conclusions:

• TBI and BMT induce significant, temporally ordered endocrine changes.
• Gonadal insufficiency and potential sterility are major long-term consequences of TBI.
• Subclinical hypothyroidism may occur, warranting further investigation and potential therapeutic strategies.