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Azizova Guzzal Djambulovna, Republic specialized scientific-practice medical center of obstetrics and gynecology, Tashkent, Uzbekistan, scientific explorer E-mail: [email protected] Azizova Dinara Shukurullaevna, Republic specialized scientific-practice medical center of obstetrics and gynecology, Tashkent, Uzbekistan, scientific explorer E-mail: [email protected]
POSTMENOPAUSAL OSTEOPOROSIS AND THE ROLE OF POLYMORPHISM OF THE VITAMIN D RECEPTOR GENE IN WOMEN OF THE UZBEK POPULATION
Abstract: In purpose of the estimate postmenopausal osteoporosis in women of tht Uzbek population, we saw 133 women in the post-menopausal period. The mean age of the patients was 57.5 ± 4.7 years. The study included women of the Uzbek population in postmenopausal women, who turned to the LLC RSSPMC of obstetrics and gynecology MH of the RUzb.
Keywords: post-menopausal period, osteoporosis, in women of tht Uzbek population.
Introduction
From the standpoint of modern medicine, it is extremely important to identify certain interrelationships and common pathogenetic mechanisms between different diseases with a view to developing a comprehensive and individual approach to the treatment and prevention of diseases.
Systemic osteoporosis is usually attributed to the inevitable age-related changes in bone tissue. The most common form of bone disease is postmenopausal osteoporosis [1; 2]. Decrease in density, and accordingly, the strength of bone tissue, inevitably arises in the process of aging of the organism, having a beginning already at the age of40-45 years [3; 2; 4]. Each subsequent year of life the woman, on average, loses 0.86-1.21% of bone mass, and the man to 0.04-0.90% [5]. Against the background of the general aging of the population, the number of patients with osteoporosis increases every year. By now, the duration of human life is high enough, in this connection, the proportion of people of elderly and senile age increases annually. According to modern data, the age of over 65 years in both sexes is identified as a separate predictor of bone fractures [6]. According to WHO data, by 2020 the number of people over 60 years will exceed the number of children under the age of 5, which will undoubtedly lead to an increase in the number of patients with osteoporosis. However, the fact that menopause is an indispensable period in the life of every woman, and a clinically significant decrease in bone density does not appear in all women, suggests that in addition to reducing the function of the gonads, there are additional factors that initiate accelerated bone loss [7; 8].
Vitamin D (25 (OH) D) is now ranked as a hormone (D-hormone). More precisely, the active metabolite of vitamin D-calcitriol (1.25-dihydroxyvitamin D3) is included in the hormone-active substance [9]. The overall effect of vitamin D on the body is aimed at stimulating calcium absorption in the intestine, as well as participation in the regulation of bone remodeling and mineralization of bone tissue [5; 10]. There is no other similar stimulator of calcium absorption in the body [11]. Besides, vitamin D affects the reabsorption of calcium and phosphorus in the renal tubules. In addition, vitamin D is able to directly change the permeability of cell membranes for calcium directly, increasing the influx of calcium into the cell [12]. This is shown on enterocytes, hepatocytes, and skeletal muscle cells [9]. Vitamin D is heterogeneous in the human body and is represented by the two most common and active forms - D2 (ergocalciferol) and D3 (cholecalciferol). The main source of vitamin D2 for people - milk, eggs, fish, cereals. Vitamin D3 - a more active form than ergocalciferol, is mainly formed endogenously, in the skin under the influence of ultraviolet, but can also come with food. The total level of vitamin D depends on the insolation, the region of residence, the duration of daylight, age, nutrition [13]. The daily requirement of a healthy adult in this vitamin is 400-800 IU [7; 13]. However, at different ages and under certain conditions (pregnancy, lactation, impaired liver function, kidney function, hypoparathyroidism), the need for vitamin D increases [8; 14; 15].
With the development of molecular biology, the study of genetic factors involved in aging processes, the knowledge
gained allowed us to consider aging as a heterogeneous product ofgenetic factors that are manifested under the influence of various environmental causes, behavioral, psychosocial and economic conditions, many of which are significantly influenced by both available and newly emerging treatment strategies. Among the factors that affect the risk of osteopenia and osteoporosis, as a consequence of changes in bone mineral density (BMD), heredity plays an important role. In the course of research, the relationship between the vitamin D receptor gene (VDR) and the above diseases was revealed. Vitamin D, when linked to its receptor, plays an important role in calcium and phosphoric homeostasis, regulating the growth and differentiation of bone cells, intestinal calcium absorption and the secretion of parathyroid hormones. Polymorphisms of the VDR gene are associated with the circulating level ofosteocalcin, weight and mineral density ofbone, osteoporotic fractures of bones [16; 17]. Polymorphisms in the gene of the vitamin D receptor (VDR) cause the genetic variability of the BMD.
Aim: To determine the possible relationship between the polymorphism of the vitamin D receptor gene and osteoporosis in postmenopausal women in the Uzbek population.
Materials and methods: The study included women of the Uzbek population in postmenopausal women, who turned to the LLC RSSPMC of obstetrics and gynecology MH of the RUzb. The mean age of the patients was 57.5 ± 4.7 years. Age of onset of menopause is 49.35 ± 3.8 years. The duration of menopause (persistent absence of menstruation for a year or more) was 6.4 ± 7.8 years.
The main complaints during treatment were: "hot flashes" to the head, severe sweating, sleep disturbances (insomnia, intermittent sleep, difficulty falling asleep), headaches, dizziness, low back pain, weakness, increased or decreased blood pressure, cramps in the calf muscles and etc.The severity of climacteric syndrome (CS) was determined with the help of a modified menopausal index (MMI) according to E. V. Uva-rova. MMI ranged from 22 to 38 points and averaged 29.3 ± ± 4.8 points. All examined women had a gynecological examination, ultrasound of the pelvic organs.
Taking into account the estrogen deficiency as the main predictor of the above postmenopausal disorders and the pres-
In order to study the state of BMD, depending on the polymorphism of the VDR gene, X-ray densitometry was performed in 89 participants of the study (see Table № 2).
In 25 women (59.5%) with the FF genotype, osteoporotic changes of the lumbar spine were detected on x-ray densitom-
ence of menopausal (climacteric) syndrome, all participants were recommended hormone replacement therapy (HRT) for 3-6 months with the aim of pathogenetic therapy, with 1 mg of estradiol and 5 mg of dydrogesterone.
Measurement of bone mineral density was performed using dual-energy X-ray absorptiometry (DXA) of the vertebrae of the lumbar region, the neck of the femur and the forearm with a Hologic apparatus (USA).
Combined preparation with a calcium carbonate content of 500 mg and vitamin D400 mg 1tab 2 times a day and preparations of cholecalciferol were recommended for patients without osteoporotic changes with a preventive goal, the dose of which was selected individually according to its indexes in the blood. Additionally alendronic acid in a dose of 75 mg 1 time per 7 days on an empty stomach 2 hours before meals were recommended for women with osteoporotic changes.
133 blood samples ofwomen of the Uzbek population in the postmenopausal period were studied for polymorphism of the VDR gene. Studies were conducted in the genomics laboratory at the Institute of Bioorganic Chemistry of the Academy of Sciences of Rep of Uzbekistan. PCR analysis was performed using a set of reagents for PCR amplification of DNA GenePak ™ PCRCore DNA (manufactured by Isogen Laboratory).
Results and discussion: Against the background of the use of hormone replacement therapy with 1 mg of estradiol and 5 mg of dydrogesterone, climacteric disorders (hot flushes to the head, severe sweating, sleep disturbance) decreased by more than 60% in all studied women. The modified menopausal index against the background of treatment ranged from 7 to 12 points and averaged 11 ± 0.8 points.
Genetic analysis of 133 DNA samples of patients revealed the following distribution of polymorphisms in the VDR gene: 64(48.12%) women were homozygous carriers of the F/F genotype, the f/f genotype was detected in 23 samples (17.29%), heterozygous F/f there were 46 patients (34.58%) (see Table № 1). The FF genotype testifies a good uptake of vitamin D receptors followed by a full-fledged effect on calcium absorption in the intestine, respectively, Ff and ff- on unsatisfactory capture.
etry, 19 (45.17%) females had osteoporotic changes in femoral neck, 10 (23.7%) had osteoporotic changes in the lower third of the forearm. As for the Ff genotype, 21 (63.6%) had osteoporotic changes in the lumbar spine, 14 (42.3%) femoral neck females, and 10 (30.3%) had osteoporotic changes in the
Table 1.
Vitamin D receptor gene FF-genotype Ff-genotype ff-genotype
n-133 64(48.12%) 46 (34.58%), 23 (17.29%)
lower third of the forearm. With the ff genotype, 6(42.87%) 5(35.7%) females had osteoporotic changes in femoral neck, women exhibited osteoporotic changes in the lumbar spine, and 3 (21.42%) in the lower third of the forearm.
Table 2. The state of bone tissue in women with polymorphism of the VDR gene
Genotype BMD Lumbar spine Neck thighs Lower third of forearm
FF(n-42) Osteoporosis 10-(23.8%) 7-(16.6%) 3-(7.14%)
Osteopenia 15-(35.71%) 12(28.57%) 7-(16.6%)
Ff(n-33) Osteoporosis 11-(33.3%) 3-(9%) 5-(15.15%)
Osteopenia 10-(30.3%) 11-(33.3%) 5-(15.15%)
ff(n-14) Osteoporosis 2-(14.3%) 0-(0%) 1-(7.14%)
Osteopenia 4(28.57%) 5(35.7%) 2-(14.28%)
Thus, in women with the genotype FF, osteoporotic changes in the lumbar spine (28.1%) were slightly less frequent than with the Ff and ff alleles (30.3%). Osteoporotic disorders in the femoral neck were found in the same number of owners of the FF genotype (21.3%) and Ff and ff(21.3%). As for the lower third of the forearm, osteoporotic changes were slightly more frequent in patients with genotypes Ff and ff(14.6%) than with the FF genotype (11.2%).
In our studies, the presence of osteoporosis was not always associated with the possession of the genotypes Ff or ff in the polymorphism of the VDR gene. Osteoporotic changes
were found even in the owners of the FF genotype, which indicates the polyetiologic nature of this pathology.
Interesting data were obtained when determining the concentration ofvitamin D in the blood of 56 postmenopausal women of the Uzbek population. Despite the prevalence of sunny days and increased insolation in our region, only one woman found a normal level of this indicator; in all others the concentration of vitamin D was reduced to different degrees (see Table № 3). The degree of saturation with this hormone was determined in terms of: norm: 30-100 ng/ml, insufficiency: 21-29 ng/ml, deficiency: 10-20 ng/ml, expressed deficiency: < 10 ng/ml.
Table 3. Indicators of vitamin D in postmenopausal women of the Uzbek population
The degree of saturation Absolute Median Min. value Maksim. value M ± m
with vitamin D amount (%) (ng/ml) (ng/ml) (ng/ml) (ng/m0
Normal 1(1.8%) 30.51 - - -
Insufficient 8(14.3%) 21.76 20.13 26.75 22.53 ± 0.95
Deficit 21(37.5%) 14.32 10.18 19.53 14.36 ± 0.74
Expressed deficiency 26(46.4%) 5.445 3 9.8 5.55 ± 0.43
The results of our studies showed that, despite the increased and prolonged insolation, women in our region need additional intake of exogenous vitamin D, as only 1.8% of participants in our survey had a normal level of vitamin D in the blood, the insufficiency of this necessary vitamin was detected in 14.3%, a deficit - in 37.5% (more than a third of women) and, finally, a pronounced deficit - in 46.4% 9 (almost half of patients).
Thus, in order to prevent the development of osteoporosis, it is extremely necessary to identify the degree of saturation with vitamin D and recommend the intake of an adequate dose of exogenous vitamin D.
The level of calcium in the blood was reduced in 10 (18.9%) patients. The median was 2.13 mmol/l, M + m =
= 2.13 + 0.02 mmol/l. A lowered level of calcium in the blood may be due to a deficiency of this macroelement and vitamin D. A lowered level of calcium in the blood can also be caused by impaired absorption of substances, kidney and liver diseases, endocrine and other disorders. The level of calcium in the blood can not be the only clear criterion of osteoporosis, since it does not indicate the calcium content in bone tissue. If the body does not receive enough of this macro-element or it is lost because of the decreased level of the female hormone estrogen, calcium begins to wash out of the bones to compensate for the deficiency in the blood. That is, bone tissue suffers so that the rest of the brain, heart, nerves, and muscles can work normally.
Table 4. The level of markers of bone metabolism after 3 months of antiresorptive therapy (M + m)
b-CrossLaps n = 12 ng/ml PINP n = 12 ng/ml Osteocalcin n = 10 ng/ml Vit.D total n = 11 ng/ml Calcium n = 12 mol/l
Outcome 0.46 ± 0.03 56.8 ±2.95 27.04 ± 1.4 11.73 ± 0.95 2.13 ± 0.02
After 3 months of therapy 0.21 ± 0.06* 36.9 ± 1.78* 21.4 ± 1.3 30.47 ± 0.96* 2.31 ± 0.06
p < 0.01 p < 0.5 P < 0.5 p < 0.01
* - p between the initial value and after therapy
Thus, our studies showed that in postmenopausal women there are significant changes in bone metabolism, characterized by the prevalence of the destruction process over the process of bone tissue synthesis.
Postmenopausal women need to examine biochemical markers of bone tissue in order to monitor the effectiveness of therapy and to adjust dosage of drugs.
After three months of anti-resorptive treatment, the levels of bone metabolism markers changed somewhat (see Table 4).
Thus, in postmenopausal women there are significant changes in bone metabolism, characterized by the prevalence of the destruction process over the process of bone tissue synthesis. Namely, the value of b-CrossLaps (bone resorption marker) was 5.8 times higher than normal (0.46 + 0.03 ng ml), while the markers of bone formation remained within normal limits. Disappointing indicators of vitamin D in the blood of our women living in the region of prolonged and active insolation: only 1.8% of participants in our survey had a normal level of vitamin D in the blood, a deficiency of this necessary vitamin was detected in 14.3%, deficiency in 37, 5% (more than a third of women) and, finally, a pronounced deficit - in 46.4% 9 (almost half of patients). Insufficiency of vitamin D promotes reducing absorption of calcium into the blood in the intestine and the development of osteoporotic changes. In order to prevent the development of osteoporosis, it is extremely necessary to identify the degree of saturation with vitamin D and recommend an adequate dose of exogenous vitamin D.
Thus, a significant number ofwomen of the Uzbek population, despite the increased and prolonged insolation, are susceptible to osteoporotic lesions of bone tissue. Therefore, residents of our region need to be examined for osteoporosis and further monitoring, as well as in the prevention and treatment of osteoporotic disorders.
So, all women in postmenopause are advisable to prevent osteoporosis with the use of calcium preparations in a daily dose of 1000 mg and vitamin D with an individual selection of its dose. In case of detection of osteoporotic changes, antiresorptive therapy is recommended.
Thus, patients with risk factors for postmenopausal osteoporosis desirability to determine the polymorphism of the vitamin D receptor gene for predicting osteoporotic changes and the beginning of their timely prevention and treatment. Bone metabolism markers (PTH, P1NP, Betta-crossLaps, osteocalcin, CT, CA), in particular vitamin D in postmenopausal women with osteoporotic changes, before treatment, as well as after 3 months, 6 months and a year later for dose adjustment and determining the duration of drug intake.
Conclusions:
1. In the absence of contraindications and the presence of symptoms of climacteric syndrome, the most valid method of treatment of postmenopausal osteoporosis remains mono-phasic combined hormone replacement therapy. An effective agent for the treatment of the syndrome is a drug containing 1 mg of estradiol and 5 mg of dydrogesterone.
2. Determination of the bone tissue state by the method of dual-energy x-ray osteodensitometry should be carried out directly in the areas of the greatest risk of fractures: in the distal forearm, lumbar spine and proximal femur, as the loss of BMD in postmenopausal osteoporosis occurs unevenly.
3. For the purpose of revealing postmenopausal osteoporosis, as well as for evaluating the effectiveness of therapy, it is necessary to conduct an annual study of the bone mineral density of the distal forearm, lumbar spine and proximal femur by dual-energy X-ray osteodensitometry.
4. In order to predict the development of osteoporotic disorders, it is advisable to carry out genetic studies on polymorphisms of the vitamin D-VDR receptor gene. Our studies showed that 51.87% of women in the Uzbek population have homozygous (ff) and heterozygous (Ff) polymorphism of the VDR gene and this group has a high risk of osteoporosis.
5. Despite the increased and prolonged insolation of women in our region, they need an additional intake of exogenous vitamin D, the dose of which must be selected individually after determining the degree of saturation.
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