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5MEDICAL SCIENCES
UDC 616.441-006:614.876:577.118 FEATURES OF MICROELEMENT SUPPLY IN THE CARPATHIAN REGION WITH VARIOUS
DEGREES OF IODINE DEFICIENCY
Skrypnyk N.,
MD, Professor, Head of the Endocrinology Department
Rybchak L.,
Clinical Ph.D. Candidate of the Endocrinology Department
Melnyk S.,
Assistant of the Department of Anesthesiology & Intensive Care
Lavruk Kh.,
Assistant of the Department of Radiology & Radiation Medicine
Gudz I.
Assistant of the Endocrinology Department Ivano-Frankivsk National Medical University, 2 Halytska str., Ivano-Frankivsk city, Ukraine
Abstract
The 90 residents of the Carpathian region have been examined within the framework of given study. The patients were divided into such groups: group I - having no thyroid pathology - control group (n = 50), group II -patients with diagnosed nodular goiter - study group (n = 20), group III - patients with diffuse endemic goiter (n = 20).
As shown by the research performed, the ioduria median was 100.45 ^g/l in the examined patients of the control group, 81.5 ^g/l in the study group of patients with nodular goiter and 66.4 ^g/l in the group of patients with diffuse goiter, which indicated the presence of mild iodine deficiency. In patients with nodular goiter and diffuse endemic goiter, the reduced level of selenium (p<0.05) was found in blood serum and hair. In the examined patients with nodular goiter, the median value of selenium in blood serum was 0.044 mg/l; in hair it was 0.18 ^g/g; in patients with diffuse endemic goiter, the median value of selenium in blood was 0.082 mg/l; in hair it was 0.4 mg/l as compared with the corresponding indices in the control group. The median value of zinc and copper content in blood serum and hair did not significantly differ in all groups. The relative risk (RR) of nodular goiter development at low selenium content in blood was 1.5 mg/g (p<0.1-0.2); at low copper content in blood it was 1.5 mg/g (p<0.1 -0.2). At low selenium level in hair, the relative risk (RR) was 1.4 ^g/g (p<0.1 -0.2) and al low copper level in hair the RR was 1.5 ^g/g (p<0.1-0.2).
Keywords: nodular goiter, thyroid gland, iodine deficiency, urinary iodine excretion, macro- and microelements, relative risk of disease.
Introduction.
A nodular goiter (NG) is an assembled clinical concept that includes all formations of the thyroid gland (TG) with different morphological structure [1, p.86]. Apart from iodine deficiency, a nodular goiter is also provoked by the deficiency of other microelements and disproportion in their correlation. The risk of developing a nodular goiter increases due to the deficiency of zinc, iron, calcium, copper, selenium and other components [2, p.64]. The importance of selenium and zinc in iodine metabolism has been also proved. Their insufficiency adversely affects the thyroid function. The numerous fundamental studies in biochemistry, molecular pharmacology of microelements have shown: both prevention and treatment of iodine deficiency conditions cannot but be related to the close connection of iodine metabolism with metabolism of other micronutrients, which are iodine synergists by their action [3, p.203]. When discussing the contribution of microelement imbalance in goiter formation, the particular attention is paid to selenium (Se) and zinc (Zn) [4, p.637]. The scientific literature presents experimental and clinical data that confirm the hypothesis on the goitrogenic action of
Zn deficiency, which is a component of over 200 metalloproteins, including the nuclear T3 receptor, which explains the need in this microelement in realization of biological effects of thyroid hormones [5, p.89]. In the structure of this receptor, the so-called zinc fingers are found - the specialized fragments of protein that che-late Zn. The Zn-containing superoxide-dismutase enzyme provides antioxidant protection of the thyroid gland, while reduction of this enzyme activity increases the risk of thyroid hyperplasia [6, p.52]. With zinc deficiency in the organism, its functional antagonists are accumulating - lead and cadmium. They are disrupting the biosynthesis processes of thyroid hormones and creating an additional burden on the thyroid gland [7, p.441].
The research purpose: establishing the features of microelement provision of population (zinc, copper and selenium content in blood and hair) of the Carpathian region with various degrees of iodine deficiency and their importance in nodular goiter development.
Materials and methods.
90 people aged from 20 to 68 years old were examined: 50 - in the control group (37 women and 13
men) aged from 32 to 64 years old, 20 - in the study group (14 women and 6 men) aged from 25 to 57 years old with diagnosed nodular goiter and 20 patients with diffuse endemic goiter (13 women and 7 men) aged from 20 to 53 years old.
The iodine study in urine of patients of the Carpathian region was carried out at the Department of Epidemiology of Endocrine Diseases of State Establishment "V.P. Komisarenko Institute for Endocrinology & Metabolism of the National Academy of Medical Sciences of Ukraine", which is included in the EQUIP International Program and constantly undergoes external quality control at the CDC Atlanta Center (USA), using the Sandell-Koltoff cerium-arsenite method in the Dunn modification [13]. The research results were interpreted according to World Health Organization criteria [12].
The ultrasound examinations of thyroid gland were performed on the SWE device (ACUSONS2000 -2013). The size of the thyroid gland was determined according to Brunn's recommendations. When estimating the thyroid volumes in adults, the limit values were used - 13 cm3 for women and 15 cm3 for men.
The determination of microelement content in hair - zinc, copper and selenium content by the atomic-absorption method, as well as the determination of microelement content in blood - zinc, copper and selenium content by the competitive immune-enzyme analysis using the atomic absorption spectrophotometer AA -7000 Shimadzu at the Bioelementology Centre of the Ivano-Frankivsk National Medical University (Direc-
tor of the Center - Doctor of Biological Sciences, Professor Ersteniuk Hanna Mykhailivna). The lower and upper limits of normal content of microelements in blood serum were for zinc 0.551 - 0.925 milligrams per liter (mg/l), for copper 0.794 - 2.023 mg/l, for selenium 0.046 - 0.14 (mg/l); in hair: for zinc 50 - 250 micrograms per gram (pg/g), for copper 7.5 - 20 pg/g and for selenium 0.2 - 2.5.
Results and their discussion.
The studies performed have shown that the ioduria median in the patients of control group was 100.45 [65.8-135.1] pg/l, in the study group of patients with nodular goiter it was 81.5 [138-25] pg/l and in patients with diffuse endemic goiter it was 66.4 [107.8-28]. Thus, if comparing with the control group, the condition of iodine supply in the group of patients with nodular and diffuse endemic goiter is significantly lower (Fig. 1).
In the control group, the median value of thyrolo-bulin (Tg) was 49.0 [38.45-59.48] pg/l. The Tg median in the study group was 19.78 [11.25-38.96] pg/l, while in the group with diffuse goiter it was 25.49 [14.5836.41] pg/l. It means that the Tg level in the group with nodular goiter significantly differed from the one in the control group. The TTH level in all groups did not exceed the level of 4 mmole/l (see Table 1). Referring to the results of ultrasound studies, the median of thyroid size in patients with nodular goiter was 19.78 [16.7622.8] cm3; the index in the control group was 12.18 [10.49-13.87] cm3, whereas in patients with diffuse goiter the median of thyroid size was 21.2 [16.89-25.68]
cm3
Table 1.
Indices of thyroid status and ioduria in the examined population of the Carpathian region.
Index Control group (n - 50) Nodular goiter (n - 20) Diffuse goiter (n - 20)
Ioduria [^g/l] 100,4 [65,8-135,1] 81,5 [138-25] 66,4 [107,8-25]
Tg fog/l] 49,0 [38,45-59,68] 25,1 [11,25-38,96] 25,4 [14,58-36,41]
Thyroid volume [cm3] 12,1 [10,49-13,87] 19,78 [16,76-22,8] 21,2 [16,89-25,68]
Thyrotropic hormone (TTH) [mmole/ml] 1,53 [1,96-2,1] 1,42 [0,96-1,88] 1,9 [0,99-2,85]
P<0,05 as compared with the control according to the Mann Whitney Test.
The median value of zinc content in blood serum in the control group was 0.69 [0.999-0.388] mg/l and in the group with diffuse endemic goiter it was 0.62 [0.987-0.256]. The zinc content in the group with nodular goiter was 0.54 [0,968-0,125] mg/l. The median value of copper content in blood serum of patients of the control group was 1.2 [2.22-0.582] mg/l, while in the group with diffuse endemic goiter it was 1.3 [2.360.255]. In patients with nodular goiter, the copper content was 1.2 [2,025-0,456] mg/l. The median value of selenium content in blood serum of patients of the control group was 0.3 [0.68-0.015] mg/l, in the group with diffuse endemic goiter it was 0.082 [0.15-0.014] mg/l, the median value of selenium content in serum of patients with nodular goiter was 0.044 [0.08-0.014] mg/l, which is significantly lower (p <0.05 according to the Mann-Whitney test) if compared with the control group (Fig. 2).
The median value of zinc content in hair in the control group was 108.9 [168-49.8] pg/g, in the group with diffuse endemic goiter it was 98.34 [158,45-38,23] pg/g. The zinc content in the group with nodular goiter was similar - 90.08 [164.8-15] pg/g. The median value of copper content in hair of patients of the control group was 12.33 [20.3-4.36] pg/g; in the group with diffuse endemic goiter it was 11.5 [20.6-2.55] pg/g. In patients with nodular goiter, the copper content was 10.3 [18.24-2.37] pg/g as compared with the control group and the group with diffuse endemic goiter. The median value of selenium content in hair of patients of the control group was 1.2 [2.4-0.045] pg/g. In the group with diffuse endemic goiter, the selenium level in hair was 0.4 [0.798-0.036] pg/g and in patients with nodular goiter the selenium content in hair was 0.18 [0.36-0.018] pg/g, which is significantly lower (p<0.05 according to the Mann-Whitney test) if compared with the control
group.
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81,5
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Figure 1. Iodine level in urine ofpatients of study groups. Control group Group with nodular goiter Group with diffuse goiter
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Figure 2. Index of selenium level in blood ofpatients of study groups. Control group Group with nodular goiter Group with diffuse goiter
CONCLUSIONS
1. The patients with nodular and diffuse goiter had mild iodine deficiency, which was indicated by the median values of ioduria in patients with nodular goiter -81.5 (g/l and 66.4 (g/l in patients with diffuse goiter, while in control group this value was 100.45 (xg/l.
2. Based on the results of microelement study in blood serum and hair in the group of patients with nodular goiter and diffuse goiter, the reduced selenium content was revealed therein in comparison with the control group.
3. In the group with nodular goiter, the reduced zinc content in blood serum was found as compared with the results obtained in the control group and patients with diffuse goiter.
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