Problems of Radiation Medicine and Radiobiology

O. V. Kaminskyi, O. V. Kopylova, D. Ye. Afanasyev, O. V. Mazurenko, S. Ya. Berezovskyi

State Institution «National Research Center for Radiation Medicine of the National Academy of Medical Sciences of Ukraine», 53 Melnykova str., Kyiv, 04050, Ukraine

Pilot study of parathyroid glands in adult and pediatric subjects exposed to ionizing radiation after the ChNPP accident, methodology of parathyroid diagnostic ultrasound

Objective. Estimation of the parathyroid hyperplasia prevalence after the ChNPP accident in adults exposed to ionizing radiation and their descendants using the diagnostic ultrasound and its methodology elaboration.
Materials and methods. The pilot prospective study of the prevalence of parathyroid hyperplasia among the Chornobyl Nuclear Power Plant (ChNPP) accident adult survivors (n=686) and their descendants (54 children) was performed using diagnostic ultrasound examination of thyroid and parathyroids. Among the study subjects there were 339 ChNPP accident clean-up workers (ACUW), 32 persons were evacuated from the 30-km exclusion zone and 224 ones were included to the control group. Diagnostic ultrasound of thyroid and parathyroids was performed according to the standard method. Additionally, in children with parathyroid hyperplasia an additional assay of 25-hydroxyvitamin D levels in serum was performed. In calculating the statistical significance, its level p < 0.05 was considered statistically significant.
Results. Parathyroids are a few small but critically important endocrine glands that synthesize parathyroid hormone, regulating mainly phosphoric-calcium metabolism. Insufficient (hypoparathyroidism) or excessive (hyperparathyroidism) function of parathyroids is harmful to the patients affecting the state of nervous and cardiovascular system. Parathyroidss can accumulate isotopes of cesium, strontium and radioactive iodine. The available data testify to an increased incidence of clinically significant hyperplasia of parthyroids (more than 9 mm in adults and more than 5 mm in children) among persons exposed toionizng radiation as a result of the accident at the ChNPP (28.64%) and their descendants (23.8–70.6%). First of all are concerned those adults who live in contaminated areas in comparison with the control group (24.15% in not irradiated). Evacuees from the 30-km exclusion zone being the category of people who were exposed to the absorbed iodine isotopes in the first days of the Chernobyl accident are the another risk group. These data demonstrate sensitivity of parathyroidss to the impact of incorporated isotopes (iodine, cesium and strontium), which in the long-term exposure create conditions for structural and functional changes in regulation of phosphorous-calcium metabolism being the basis for a significant prevalence of osteopenia and osteoporosis in irradiated individuals and their descendants. A number of further studies are required to clarify the findings and to disclose the hormonal mechanisms of radiation effects on parathyroids.
Conclusions. Parathyroid glands are radiosensitive and susceptible to effects of strontium, cesium and iodine isotopes, which cause parathyroid irradiation and subsequent structural and functional changes, being a prerequisite for development of osteopenia and osteoporosis in the ChNPP accident survivors and their descendants. High incidence of parathyroid hypertrophy is found in the inhabitants of the radiation-contaminated territories (long-term irradiation by cesium isotopes), as well as in evacuated from the 30-km exclusion zone (irradiation by iodine isotopes in the early days of the accident).
Key words: accident at ChNPP, irradiation, accident survivors, accident clean-up participants, ionizing radiation, children, parathyroid glands, hyperplasia.

Problems of radiation medicine and radiobiology. 2017;22:382–394.