Endocrine Abstracts

Introduction: Since the hypothalamic-puituitary axis (HPA) is a radiosensitive region, cranial radiotherapy for head and neck malignancies represents a major risk factor for the development of endocrine complications particularly hypopituitarism.

Case report: A 22 years old girl with a history of a undifferentiated carcinoma of nasopharyngeal type UCNT at the age of 09 years old treated with radiotherapy and chemotherapy was referred to the endocrinology department for investigation of short stature and primary amenorrhea. The patient presented with short stature, height of 146 cm (–3 standard deviations), with normal weight (body mass index 24 kg/m2), Breast Development Scale stage 4 and Pubic Hair Scale stage 4. Radiography of the left hand revealed a bone age of 15 years. Dynamic growth hormone evaluation showed unstimulated levels. The Endocrine investigation was consistent with hypopituitarism (corticotropic insufficiancy, gonadotrop insufficiancy, central hypothyroidism and GH deficiency). However, Prolactin levels were normal. Pituitary MRI showed hypotrophic pituitary gland with partial intrasellar arachnoidocele, and a bilateral postradic demyelination of temporal white matter. Pelvic MRI revealed an uterine and ovarian atrophy. Hormonal substitution therapy with glucocorticoids levoT4 and sex steroids was started.

Discussion: RIH (radiotherapy induced hypopituitarism) is a slow-developing process. Its development dependens on RT per fraction dose, post-RT interval radiation dose, age, the volume of the HPA irradiated. In addition, the incidence of RIH increases with the total dose. However, it should be noted that this incidence does not have a specific threshold dose since cases with doses as low as 20 gy were documented. This further highlights the importance of early detection. Some studies have suggested that the growth hormone deficiency is the first manifestation of RIH followed by deficiencies in gonadotropin, ACTH, and TSH. Moreover, the dysfunction of the hypothalamus leads to the reduction of dopamine release. Hence, hyperprolactinemia, which contributes to gonadal dysfunction, can be present on a case by case basis. Despite the fact childhood cancer survival rates have improved across all measures, survivors are still at risk of developping endocrine disorders, even years removed from therapy. This accentuates the importance of lifelong surveilance.

Conclusion: RIH worsens the quality of life and reduces the life span of patients. Thus, successefull management depends greately on early detection and hormone replacement therapy.