Clinical-Metabolic and Hormonal Relationships Between Parathyroid Disease and Other Non-Cancerous Endocrine Disorders in the Chornobyl NPP Accident Survivors

Abstract

Objective: to investigate the clinical, hormonal-metabolic and structural features of parathyroid injuries in survivors exposed to ionizing radiation after the Chornobyl NPP accident in adulthood and childhood, both with their connections to other non-cancerous endocrine disorders, and to establish the respective interhormonal and dysmetabolic relationships. Materials and methods. Clinical effects of ionizing radiation on the endocrine system in persons affected by the Chornobyl NPP accident (n = 224) and their descendants (n = 146), compared with the general population sample (n = 70) were the study object. All patients underwent the ultrasound thyroid and parathyroid examination. The generally recognized clinical, anthropometric (body weight, height, thigh volume, body mass index), instrumental (ultrasound examination of thyroid and parathyroid glands), laboratory (biochemical, hormonal), and statistical methods were applied. Parametric and nonparametric statistical methods were used in data processing. The value of p < 0.05 was considered a statistically significant. Results. No significant difference was found in the incidence of carbohydrate metabolic disorders in the Chornobyl NPP (ChNPP) accident consequences clean-up workers (ACCUW), evacuees from the NPP 30-km exclusion zone, residents of radiologically contaminated areas and in the control group in whom the parathyroid hyperplasia was detected. There was a significant increase in the incidence of arterial hypertension among ACCUW who had parathyroid hyperplasia (76.9%) vs. the control group (51.2%). In cases of parathyoid hyperplasia the vitamin D levels were significantly lower than without it. Vitamin D insufficiency/deficiency was found in 94% of the surveyed subjects. The average level of parathyroid hormone in blood serum was significantly higher in the ACCUW of «iodine» period with diagnosed parathyroid hyperplasia than in the control group: (57.2 ± 2.87) pg / ml against (32.74 ± 3.58) pg / ml, p < 0.05. Results of multivariative analysis indicated a strong association of vitamin 25(OH)D insufficiency/deficiency with development of thyroid disease, carbohydrate metabolic disorders, cardiovascular disease, osteopenia/osteoporosis. parathyroid ultrasound scan was at that an effective diagnostic method for primary screening for parathyroid hyperplasia and regular monitoring of the treatment efficiency. When examining children born to parents irradiated after the ChNPPA the parathyroid hyperplasia (58%) and low serum content of vitamin D (11.6 ± 3.5) nmol / l were most often found in children living on radiologically contaminated territories (RCT). A strong correlation was established between the HOMA insulin resistance index and serum content of vitamin D (r = 0.65), parathyroid hormone (r = 0.60), and free thyroxine (r = 0.68) in the group of children born to parents irradiated after the ChNPPA, having got chronic autoimmune thyroiditis, which indicated a relationship between thyroid function, impaired carbohydrate and fat metabolism and the state of parathyroids. Conclusions. No difference in the incidence of carbohydrate metabolic disorders was found in the ChNPP ACCUW, evacuees from the 30-km exclusion zone, and residents of radiologically contaminated territories in whom parathyroid hyperplasia was detected vs. the control group. Patients with parathyroid hyperplasia were found to be defi cient in vitamin D in 94% of cases, and level of latter was significantly lower than under the normal parathyroid size. There was a significant increase in the incidence of diagnosed arterial hypertension among ACCUW who had parathyroid hyperplasia vs. the control group: (76.9 ± 3.5)% vs. (51.2 ± 3.7)%. According to multivariate analysis a strong association between the vitamin 25(OH)D insufficiency/deficiency and development of thyroid disease, carbohydrate metabolic disorders, cardiovascular disease, and osteopenia/osteoporosis was established. The average level of parathyroid hormone in the blood serum of the ChNPP ACCUW of the «iodine» period with diagnosed parathyroid hyperplasia was significantly higher (57.2 ± 2.87) pg / ml against (32.74 ± 3.58) pg / ml; p <0,05) in the control group. Key words: ChNPP accident, irradiation, accident survivors, accident consequences clean-up workers, ionizing radiation, parathyroids, hyperplasia, hyperparathyroidism, thyroid.