Effects of combined oral contraceptive pills on thyroid function tests in Mosul City

Background: There are very little studies to determine the effects of combined oral contraceptive pills (COCPs) on thyroid function tests in hormonal contraceptive users at least in our locality. Objective: To evaluate the effects of COCPs on serum level of thyroid stimulating hormone (TSH) , free triiodothyronine (FT٣) and free tetraiodothyronine (thyroxine) (FT٤) and in relation to the duration of their usage in Mosul City. Design: A case control study. Subject & Methods: This study was conducted during the period from September ٢٠٠٨ to March ٢٠٠٩. A total of ٧٨ healthy married women , age range between ١٩-٣٥ years, from those who were attending AL–Batool and AL-Khansa Family Planning Centers in Mosul, who were taking Microgynon tablets which are one of monophasic, second generation combined oral contraceptive pills (COCPs) (contain ٠.٠٣ mg of ethinyl estradiol and ٠.١٥ mg levonorgestrel) (N=٤٨) for a period ranged between ٣ months to ٥ years and these were considered the users group. Other ٤٠ healthy married women who did not use any hormonal contraceptives and were drawn from the same population and matched for age, body mass index (BMI) with the users group and they were considered as the non users groups. Blood samples (٥ml) were obtained from COCPs users and non-user groups. The sera obtained from the blood samples were used for the estimation of serum TSH, FT٣, FT٤ using Menividus analytic device. Results: This study revealed non significant differences in TSH , FT٣ and FT٤ serum levels between COCPs users and non users and no correlation between serum TSH, FT٣ and FT٤ levels and duration of hormonal contraceptives usage. Conclusion: This study supported that the free thyroid hormone tests are the tests of choice in assessing thyroid function of women taking COCPs and concluded that COCPs can be regarded as a safe drugs in women using these types of hormonal as far as thyroid function is concerned. صلاخلأ ة ةيفلخلا : ةآرتشملا لمحلا عنم بوبح ريثأت ريرقتل ادج ةليلق تاسارد دجوي ى لع ةد غلا ة فيظو ل قلأا ى لعو ة يقردلا اننتقطنم يف . فدهلا : ريثأت مييقتل بوبح لا لمحلا عنم ةآرتشم ى لع ة يقردلا هد غلل ز فحملا نو مرهلل مد لا لصم ىوتسم ) سا ي ت جا ( ، ينورياثلا رحلا دويلا يثلاثلا ن ) يرث يت فا ( حلا نيسآورياثلاو ر ) رو ف يت فا ( ه تقلاعو ةر تفب مادختسا اه ةنيدم يف لصوملا . ةساردلا ميمصت : ةلاح ةسارد ميمصت . Irq J Pharm Vol. ١١, No. ١, ٢٠١١ قرطلا ةعبتملا صاخشلأاو : لوليأ نم ةرتفلا نيب ةساردلا هذه تيرجا ٢٠٠٨ راذآ ة يغلو ٢٠٠٩ عومجم ذخأ م ت ٧٨ ةأر ما ني ب نهرا معأ حوار تت ةميل س ) ١٩ – ٣٥ ( ىف شتسم ي ف هر سلاا مي ظنت يز آرم نعجار ي ن آ ن مم ةن س نلمعتسي نممو لصوملا يف ءاسنخلاو لوتبلا إ ةآرتشملا لمحلا عنم بوبح ام " نونيجوركيا م " ى لع يو تحت ي تلاو لويادارتسأ ليانيثأ ) ٠٣ ‚ ٠ مغلم ( ليرتسيجرونوفيلو ) ١٥ ‚ ٠ مغلم ( م بو بح نم دحاو وهو ة ينومرهلا لمحلا ع ناو ا لأ ينا ثلا ل يجلا ن مو ه يداح ) نهدد ع ٤٨ ( تاون س سمخ ى لإ ره شأ ة ثلاث ني ب حوار تت ةر تفل ، م ت ءا سنلا ءلاؤ ه نهرابتعا " ةينومرهلا لمحلا عناوم يلمعتسم ةعومجم " عم نهتنراقمو ٤٠ سفن نم ىرخأ ةميل س ةجوزتم ةأرما نلمعتسي لا نمم نزولاو لوطلاو ةيرمعلا ةئفلا ةرطيس وأ طبض ةعومجمآ نهرابتعا متو ةينومرهلا لمحلا عناوم . راد قمب مد بحس مت ٥ سا يقل مد لا جذا من نم ذوخأ ملا مد لا لصم تا نيع مادخت سا م ت نيتعو مجملا لاآ نم س س زا هج لامعتساب ة يراجتلا ةيوديلا ددعلا ةطساوب هيوايميكلا تاصوحفلا د ياف ي نملا ز ي ليلحتلا . مد لا طغض سا يق م ت نزو لا ةم سق ن م م سجلا ة فاثآ سا يقم با سح م تو طاغ ضملا مادخت ساب سو لجلا ةيع ضوب ) م غآ ( ع برم ى لع لوطلا ) رتم .( جئاتنلا : ةساردلا هذه ترهظأ قرف ريغ زيمم ة يقردلا هد غلل ز فحملا نومرهلل مدلا لصم ىوتسم يف ايئاصحإ ) ي ت جا سا ( ، رحلا دويلا يثلاثلا نينورياثلا ) يرث يت فا ( اثلاو رحلا نيسآوري ) رو ف ي ت فا ( تلامعت سم ني ب بو بح ل محلا ع نم ة نراقم ةآرت شملا ر يغب تلامعت سملا و ةد غلا تا نومرهل مد لا لصم ىوت سم ني ب ة قلاع دو جو مد ع ةيقردلا ) جا سا يت ( ، ) يرث يت فا ( و ) روف يت فا ( ةينومرهلا لمحلا عناوم مادختسا ةرتفو . جاتنتسلاا : تخا نأ تمعد ةساردلا هذه ا وه ة يقردلا ةد غلا ة فيظول ةرحلا تا نومرهلا راب لأ مي يقت ي ف لضفلأا را بتخ تلامعتسم ىدل ةيقردلا ةدغلا ةفيظو لمحلا عنم بوبح ةآرتشملا نأ تجتنتساو لمحلا عنم بوبح ةآرتشملا ر بتعت ةبسنلاب هنيملأأ ةيودلأا نم ةيقردلا ةدغلا ةفيظول تلامعتسم ىدل نم عونلا اذه لمحلا عناوم ا ةينومرهل . t has been reported that estrogen increase serum thyroxin-binding globulin (TBG) concentration because this hormone may enhances hepatic production of TBG and decrease TBG clearance , thus increasing serum total tetraiodothyronine (thyroxine) (TT٤) and to a lesser extent total triiodothyronine (TT٣) . As a result, increased TT٤ and TT٣ are seen in states of excessive estrogen and/or progestin, such as pregnancy, hormonal replacement therapy (HRT) and oral contraceptives usage . This phenomenon may cause problems in clinical diagnoses when TT٤ or TT٣ is used for these patients. Oral contraceptives (birth control pills) are medicines taken by mouth to help in preventing pregnancy, contain artificially made form of two hormones naturally produced in the body (estrogen and progesterone) so called COCPs . They are the most effective, safe, reliable and popular form of reversible contraception . The results of a study done by Duijkers et al. ٨ on healthy women aged ١٨-٤٠ years used either vaginal ring delivering ٠.٠١٥ mg ethinyl estradiol and ٠.١٢ mg of etonogestrel per day, or COCPs containing ٠.٠٣ mg ethinyl estradiol and ٠.١٥ mg levonorgestril for six cycles, found that both the vaginal ring and the oral contraceptive have no clinically relevant effects on carbohydrate metabolism, adrenal or thyroid function tests. Other study about the effects of sex-steroid administration on the pituitary-thyroid axis in trans sexuals, concluded that estrogens do not affect T٣/T٤ ratio, irrespective of the route of administration. Whereas Shifren et al. ١٠ suggested that in comparison with COCPs, transdermal route exerted minimal effects on the total and free concentrations of T٤, T٣ and their binding proteins. In contrast to what would be expected theoretically the study done by Grüning et al ., ١١ found that FT٣ values decreased significantly during COCPs usage while TSH and TT٤ were unaffected. In a recent cohort study done by Sänger et al. in ٥٩ women ingested I Irq J Pharm Vol. ١١, No. ١, ٢٠١١ this monophasic COCPs for ١٣ cycles, the serum concentrations of TBG were elevated by about ٦٥% , likewise, an increase in TT٣ and TT٤ by ٣٠-٤٠%, but non significant changes in free T٤ were found. The aim of this study is to assess the effect of COCPs Microgynon (٠.٠٣ mg Ethinylestradiol (EE) and ٠.١٥٠ mg Levonorgestrel (LNG)) on thyroid function tests (TSH, FT٤ and FT٣), and in relation to the duration of use by these hormonal contraceptive users in comparison to non users aged matched women

) and to a lesser extent total triiodothyronine (TT ٣ ) ١,٣ .As a result, increased TT ٤ and TT ٣ are seen in states of excessive estrogen and/or progestin, such as pregnancy, hormonal replacement therapy (HRT) and oral contraceptives usage ٤,٥ .This phenomenon may cause problems in clinical diagnoses when TT ٤ or TT ٣ is used for these patients.
Oral contraceptives (birth control pills) are medicines taken by mouth to help in preventing pregnancy, contain artificially made form of two hormones naturally produced in the body (estrogen and progesterone) so called COCPs ٦ .They are the most effective, safe, reliable and popular form of reversible contraception ٧ .
The results of a study done by Duijkers et al. ٨ on healthy women aged ١٨-٤٠ years used either vaginal ring delivering ٠.٠١٥ mg ethinyl estradiol and ٠.١٢ mg of etonogestrel per day, or COCPs containing ٠.٠٣ mg ethinyl estradiol and ٠.١٥ mg levonorgestril for six cycles, found that both the vaginal ring and the oral contraceptive have no clinically relevant effects on carbohydrate metabolism, adrenal or thyroid function tests.
Other study ٩ about the effects of sex-steroid administration on the pituitary-thyroid axis in trans sexuals, concluded that estrogens do not affect T٣/T٤ ratio, irrespective of the route of administration.Whereas Shifren et al. ١٠ suggested that in comparison with COCPs, transdermal route exerted minimal effects on the total and free concentrations of T٤, T٣ and their binding proteins.In contrast to what would be expected theoretically the study done by Grüning et al ., ١١ found that FT٣ values decreased significantly during COCPs usage while TSH and TT٤ were unaffected.
In a recent cohort study done by Sänger et al. ١٢ in ٥٩ women ingested I this monophasic COCPs for ١٣ cycles, the serum concentrations of TBG were elevated by about ٦٥% , likewise, an increase in TT٣ and TT٤ by ٣٠-٤٠%, but non significant changes in free T٤ were found.
The aim of this study is to assess the effect of COCPs Microgynon (٠.٠٣ mg Ethinylestradiol (EE) and ٠.١٥٠ mg Levonorgestrel (LNG)) on thyroid function tests (TSH, FT٤ and FT٣), and in relation to the duration of use by these hormonal contraceptive users in comparison to non users aged matched women as control.

Subjects and Methods
The Five ml of venous blood were withdrawn, using a disposable syringe from the contraceptive users and non-users.The blood was allowed to clot in a plain tube at room temperature and then the serum was separated by centrifugation at ٣٠٠٠ rpm for ١٠ minutes and then kept frozen at -٢٠ °C to be analyzed thereafter.Serum TSH, FT٤ and FT٣ were measured, using the ELFA technique (enzyme linked fluorescent assay), and TSH, FT٤ and FT٣ kits ( Ref. ٣٠ ٤٠٠, ٣٠ ٤٠١ and ٣٠ ٤٠٢ respectively ) from biomerieux, France were used.
Standard statistical methods were used to determine the mean and standard deviation (SD).Unpaired student t-test was used to compare the results for measured biochemical parameters between hormonal contraceptive users and non-users.
Linear regression analysis [Pearson correlation coefficient (r)] was performed for finding the degree of association between different parameters.ANOVA Test (Analysis of Variance) was used to identify the variation in the different variables in relation to the duration of hormonal contraceptive user groups.P< ٠.٠٥ was considered to be statistically significant.
The approval of the study protocol by an ethic committee has been obtained from the Local Health Committee, Ministry of Health and College of Medicine, University of Mosul, Iraq.

Results
A total number of ٤٨ women who used COCPs were included in this study, with mean age ± SD of ٣٠.٤٦±٣.٤٠),those have been considered to represent the exposed (COCPs users) group.Another ٤٠ women with mean age ± SD of ٢٩.٠٥±٤.٥٠years, who did not use or used non hormonal contraceptives such as condom or IUCDs and were considered to represent the non exposed group (non-users) group.
No significant differences between the mean serum TSH, FT٣ and FT٤ levels in the COCPs users compared with the non users (Table ١) .

Discussion
The hormonal contraceptive used in this study was "Microgynon" tablets, which is one of the monophasic, second generation COCPs (٠.٠٣ mg ethinly estradiol and ٠.١٥ mg levonorgestrel), because COCPs are the most commonly used method of contraception in Iraq, as it was found that oral pills represent the most popular, about ٣٦% of current users use oral pills ١٣ .Also, in another study done in Mosul City ١٠ , found that the most common type of contraceptive methods used was the oral pills, (٤٢.٦%) (including COCPs in ٣٢.٣% and progesterone only pills (POPs) in ١٠.٣%) of the users ١٤ .
Since the introduction of hormonal contraceptives in the early ١٩٦٠s, repeated attention has been focused on possible beneficial and harmful side effects ١٥ .Among the possible impact, the relation between hormonal contraceptive use and thyroid function tests has been studied but the results of these studies, however, have been equivocal.This study found that there were no significant changes in the mean serum levels of TSH, FT٣ and FT٤ among COCPs users in comparison to the non-users, which is in agreement with many studies ٨,١٢,١٦ , who found no significant differences in thyroid parameters in women taking COCPs containing ethinly estradiol and levonorgestrel in comparison to the control.In a recent cohort study done by Sänger et al., ١٢ in ٥٩ women ingested this monophasic COCPs for ١٣ cycles, the serum concentrations of TBG were elevated by about ٦٥% , likewise, an increase in TT٣ and TT٤ by ٣٠-٤٠%, but non significant changes in free T٤ were found.
Other two studies ١٧,١٨ in agreement with our results and concerning thyroid reference levels, concluded that the use of oral contraceptives was a significant predictor for variation in TT٤ and TT٣ concentrations due to estrogen-mediated TBG-induced hepatic synthesis, where as FT٤ and FT٣ were insignificantly affected and that the use of contraceptives should be considered in diagnostic evaluation of thyroid diseases owing to their capacity to modulate the limits of thyroid hormone distinct reference intervals.
The present study showed no correlation between serum TSH, FT٣ and FT٤ levels and duration of hormonal contraceptive usage which indicates that the effects of contraceptives on thyroid tests is time independent.In line with this, Sänger et al., ١٢ observed that during hormonal contraceptive usage, a steady state in the effects on thyroid hormones and androgen parameters was reached within ٣ months and that the changes in the various hormonal parameters did not substantially differ between conventional and extended-cycle regimen.
In the present study, the free hormones (FT٣ & FT٤) were evaluated instead of the routinely measured total forms (TT٣ & TT٤) in Iraq, since total test is a measure of bound and free hormone, and the change in the level of thyroid hormone binding protein, as in subjects using oral contraceptives, produce corresponding changes in the total T٤, even though levels of physiologically active free T٤ are unchanged ١,٥,١٩ ; thus a patient may be physiologically normal but has an abnormal total serum hormonal level.So, FT٣ and FT٤ in the serum can be measured directly , avoiding the hazard of interpreting total levels ٢٠,٢١ .Furthermore, because the free rather than bound thyroid hormone is subjected to homeostatic control by the hypothalamicpituitary-thyroid axis ٢٢ , estimation of free thyroid hormone concentrations are theoretically preferable to TT٤ and TT٣ tests, indicating that free serum thyroxin is the test of choice in assessing the functional thyroid status of women taking oral COCPs or HRT ٢,٢٢ .
In conclusion, COCPs can be regarded as a safe drugs in women using these hormonal contraceptives as far as thyroid function is concerned and the use of free thyroid hormone tests should be followed instead of measuring the total thyroid hormone in assessing thyroid function of women taking hormonal contraceptives.

Table ١ :
Comparison between mean serum levels of measured thyroid hormones of COCPs users and non-user groups Fadhel NN.Knowledge, Altitude and Practice of Contraceptive Methods among Iraqi Women.MSc