Evaluation of Serum Homocysteine Levels in Pregnant Patients with Graves' Disease

Transcription

1 ORİJİNAL ARAŞTIRMA Evaluation of Serum Homocysteine Levels in Pregnant Patients with Graves' Disease Dilek BERKER, MD, a Serhat IŞIK, MD, a Yusuf AYDIN, MD, a Ufuk ÖZUĞUZ, MD, a Yasemin TÜTÜNCÜ, MD, a Gönül ERDEN, MD, b Serdar GÜLER, MD a Clinics of a Endocrinology and Metabolism, b Biochemistry, Ankara Numune Research and Training Hospital, Ankara Ge liş Ta ri hi/re ce i ved: Ka bul Ta ri hi/ac cep ted: Ya zış ma Ad re si/cor res pon den ce: Dilek BERKER, MD Ankara Numune Research and Training Hospital, Clinic of Endocrinology and Metabolism Ankara, TÜRKİYE/TURKEY dberker6@yahoo.com ABS TRACT Ob jec ti ve: In se ve ral stu di es, se rum ho mocy ste i ne le vels we re fo und nor mal or low in hyperth yro i dism and low in preg nancy. Hyper ho mocy ste i ne mi a and thyro to xi co sis may in di vi du ally ca u se va ri o us comp li ca ti ons in preg nancy. In this study we ai med to eva lu a te se rum to tal ho mocy ste i ne (thcy) le vels in preg nant with Gra ves di se a se. Ma te ri al and Met hods: Twenty-two newly di ag no sed thyro to xic preg nant wo men (gra vi da 1, preg nancy we eks 12 th -16 th, ave ra ge age 24.0 ± 2.8) and 20 he althy preg nant wo men (gra vi da 1, preg nancy we eks 12 th -16 th, ave ra ge age 23.1 ± 3.0) we re inc lu ded in the study. Fas ting blo od tests we re per for med for thyrot ro pin (TSH), fre e thyro xi ne (FT4), fre e tri i o doth yro ni ne (FT3), TSHre cep tor an ti body (TRAb), ho mocy ste i ne (thcy), vi ta min B 12, fo la te, and al bu min. Re sults: The re we re no sig ni fi cant dif fe ren ces bet we en the 2 gro ups with re gard to age (24.0 ± 2.8 and 23.1 ± 3.0 res pec ti vely) (p= 0.265). Vitamin B 12, fo la te, and al bu min le vels we re not sig ni fi cantly dif fe rent bet we en the thyro to xic and con trol gro up. The ove rall me an ho mocy ste i ne con cen tra ti on of the thyro to xic preg nant sub jects (9.6 ± 2.9 µmol/l) was sig ni fi cantly hig her than con trol gro up (5.0 ± 1.9 µmol/l) (p< 0.001). Ho mocy ste i ne le v- els we re po si ti vely cor re la ted with FT3 le vels (r= 0.390, p= 0.01) and ne ga ti vely cor re la ted with TSH le - vels in both thyro to xic and non-thyro to xic gro ups (r= , p= 0.01). Ho we ver, no cor re la ti on was fo und bet we en FT4 and thcy le vel. Ave ra ge TRAb le vel of the pa ti ents was 16.6 ± 3.2 IU/L (mi ni mum 12.8 IU/L and ma xi mum 23.4 IU/L). No cor re la ti on was fo und bet we en TSH re cep tor an ti body and thcy le vel. Conc lu si on: In this study, we ob ser ved that se rum ho mocy ste i ne le vels in thyro to xic preg nant wo men with Gra ves di se a se we re hig her than con trol gro up. The re is a ne ed for lar ge sca le stu di es com pa ring pre- and post-tre at ment ho mocy ste i ne le vels in hyper-hypoth yro id ca ses of preg nant and non-preg nant in di vi du - als. Key Words: Gra ves di se a se; ho mocy ste i ne; thyro to xi co sis; preg nancy ÖZET Amaç: Bir çok ça lış ma da se rum ho mo sis te in se vi ye le ri hi per ti ro i dizm de nor mal ya da dü şük, ge be - lik te ise dü şük bu lun muş tur. Hi per ho mo sis te i ne mi ve ti ro tok si koz bir bi rin den ba ğım sız ola rak ge be lik te pek çok komp li kas yon dan so rum lu ola bil mek te dir. Gra ves has ta lı ğı olan ge be ler de se rum to tal ho mo sis te in (thcy) dü zey le ri ni de ğer len dir mek ama cıyla bu ça lış ma yı plan la dık. Ge reç ve Yön tem ler: Ye ni ta nı al mış 22 ti ro tok sik ge be has ta (gra vi da 1, ge be lik haf ta sı) ile 20 sağ lık lı ge be (gra vi da 1, ge be lik haf - ta sı) ça lış ma ya da hil edil di. Aç lık se rum ti rot ro pin (TSH), ser best ti rok sin (st4), ser best tri i yo do ti ro nin (st3), TSH re sep tör an ti ko ru (TRAb), vi ta min B 12, fo lat ve thcy dü zey le ri ça lı şıl dı. Bul gu lar: Ti ro tok sik ge be ler ile kon trol gru bu nun yaş or ta la ma la rı ben zer di (sı ra sıy la 24.0 ± 2.8 ve 23.1 ± 3.0, p= 0.265). Ti ro - tok sik has ta lar ile kon trol gru bu ara sın da se rum fo lat, vitamin B 12 ve al bu min dü zey le rin de an lam lı fark - lı lık yok tu. thcy dü zey le ri ti ro tok sik ge be ler de (9.6 ± 2.9) kon trol gru bu na (5.0 ± 1.9) oran la an lam lı dü zey de da ha yük sek ti (p< 0.001). Ti ro tok si koz lu ve kon trol ge be grup la rın her iki sin de st3 dü ze yi ile thcy dü ze - yi ara sın da is ta tis tik sel ola rak an lam lı po zi tif ko re las yon (r= 0.390, p= 0.01) ve TSH dü ze yi ile thcy dü zey - le ri ara sın da is ta tistik sel ola rak an lam lı ne ga tif yön de ko re las yon iz len di (r= , p= 0.01). Bu nun la bir lik te st4 dü ze yi ile thcy dü ze yi ara sın da iliş ki sap tan ma dı. Has ta la rın or ta la ma TRAb dü ze yi 16.6 ± 3.2 IU/L (mi ni mum 12.8 IU/L ve mak si mum 23.4 IU/L) ola rak sap tan dı. TSH re sep tör an ti ko ru ile thcy dü ze - yi ara sın da iliş ki bu lun ma dı. So nuç: Ça lış ma mız da Gra ves has ta lı ğı sap ta nan ti ro tok sik ge be ler de nor mal ge - be le re gö re se rum thcy dü zey le ri da ha yük sek bu lun du. Bu ko nu da ge be ve ge be ol ma yan bi rey ler de hi per-hi po ti ro i di du rum la rın da te da vi ön ce si ve son ra sı ho mo sis te in dü zey le ri nin kar şı laş tı rıl dı ğı ge niş çap lı ça lış ma la ra ih ti yaç var dır. Anah tar Ke li me ler: Gra ves has ta lı ğı; ho mo sis te in; ti ro tok si koz; ge be lik Cop yright 2009 by Tür ki ye Kli nik le ri Turkiye Klinikleri J Gynecol Obst 2009;19(3):155-9 Turkiye Klinikleri J Gynecol Obst 2009;19(3) 155

2 Dilek BERKER et al EVALUATION OF SERUM HOMOCYSTEINE LEVELS IN PREGNANT PATIENTS WITH GRAVES' DISEASE hyroid hormones increase oxidative system as they induce basal metabolic rate and specific mitochondria enzymes, consequently result in free radical formation. 1 Overt hypothyroidism and thyrotoxicosis have well-documented adverse impacts on pregnancy outcomes. 2-4 Graves disease (GD) is an autoimmune disorder causing hyperthyroidism, in which the thyrotrophin receptor antibody (TRAb) acts as a stimulator of the thyroid gland. Similar to other autoimmune diseases, the prevalence of GD is much more common in females than males, particularly in women of childbearing age. Because untreated GD during pregnancy results in an increased frequency of complications such as miscarriage, stillbirth, preterm delivery and intrauterine growth retardation. 5 Generally, in human studies, serum homocysteine levels were found normal or low in hyperthyroidism Homocysteine is an amino acid whose effect is similar to that of free radicals, which is recently acknowledged to be included in oxidative system and which is not classified under proteins Hyperhomocysteinemia has also been associated with complications in pregnancy, such as neural tube defects, repeated miscarriages, abruptio placentae, fetal death, preeclampsia and intrauterine growth retardation. 14,15 Various studies show that homocysteine concentrations are physiologically lower in normal pregnancies. 16,17 As we have not encountered studies on homocysteine levels in pregnant women with hyperthyroidism, we studied if there is a difference between the serum homocysteine levels of women with thyrotoxic pregnancy and normal pregnancy. MATERIAL AND METHODS STUDY GROUP AND DESIGN Twenty-two newly diagnosed thyrotoxic pregnant women (gravida 1, pregnancy weeks 12 th -16 th, average age 24.0 ± 2.8) and 20 healthy pregnant women (gravida 1, pregnancy weeks 12 th -16 th, average age 23.1 ± 3.0) were included in the study. Pregnant women with diabetes mellitus, impaired glucose tolerance, connective tissue disease, hypertension, coagulation disorder, atherosclerotic disease, smoking history, active infection and inflammation findings and nodules in thyroid ultrasonography larger than 1 cm were excluded. The diagnosis of GD was based on the clinical signs of hyperthyroidism combined with suppressed serum thyrotropin and positive thyrotropin receptor antibodies. Informed consent was obtained from all participants. LABORATORY ANALYSIS Venous blood samples were obtained after fasting overnight for 8-10 hours and a resting period of 20 minutes. After 30 minutes they were centrifuged for 10 minutes at 3000 g and were assayed after being separated. Homocysteine specimens were centrifuged at 4 C for 10 minutes at 3000 g and sera were stored at -20 C until assayed. We measured serum thyroid stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxin (FT4), serum vitamin B 12 and serum folate levels by an immunoluminometric assay on a random-access analyzer (Architect i2000; Abbott Diagnostics Division). Biological principle of the procedure was chemiluminescent microparticle immunoassay (CMIA). Patients who had TSH levels lower than 0.35 µiu/ml and FT3 and FT4 levels above reference ranges (> 3.71 pg/ml and > 1.48 ng/dl; respectively) were accepted as having hyperthyroidism. TSH TRAb was studied with RADIM brand kit and radioimmunassay (RIA) method (normal < 10 IU/L). Serum albumin was analyzed on the Olympus-AU2700 with photometric method using original kits in biochemistry autoanalyser. Homocysteine assays were studied using Recipe Chemicals kit following HPLC method and utilizing Shimadzu brand HPLC device (reference ranges for homocysteine µmol/l). STATISTICAL ANALYSIS The Statistical Package for the Social Sciences (SPSS version 13.0 for Windows) was used for statistical analyses. Descriptive statistics are expressed as mean +/- standard deviation. Continuous variables were compared with Mann-Whitney U test. The chi-square test was used for categorical variables. p values of less than 0.05 were considered, statistically significant. Correlations between vari- 156 Turkiye Klinikleri J Gynecol Obst 2009;19(3)

3 EVALUATION OF SERUM HOMOCYSTEINE LEVELS IN PREGNANT PATIENTS WITH GRAVES' DISEASE Dilek BERKER et al ables were tested using the Spearman rank correlation test. RESULTS There were no significant differences between the 2 groups with regards to age (24.0 ± 2.8 and 23.1 ± 3.0 in group 1 and 2 respectively) (p= 0.265). Serum albumin, folate and vitamin B 12 levels were similar between pregnant women with thyrotoxicosis and the control group (Table 1). However, thcy levels were significantly higher in the pregnant women with thyrotoxicosis (9.6 ± 2.9) than the control group (5.0 ± 1.9) (p< 0.001). Statistically significant negative correlation was followed between TSH level and thcy levels (r= , p= 0.01). Statistically significant correlation was found between FT3 level and thcy level (r= 0.390, p= 0.01). However, no correlation was found between FT4 and thcy level. Average TRAb level of the patients was 16.6 ± 3.2 IU/L (minimum 12.8 IU/L and maximum 23.4 IU/L). No correlation was found between TSH receptor antibody and thcy level (Table 2). DISCUSSION Previous studies showed that homocysteine (thcy) level decreased in pregnancy. 16,17 The mechanism responsible for this decrease in thcy concentration is not known but increased use of metionin by fetus, increase in estrogen and cortisol hormones TABLE 1: Comparison of groups in terms of age and laboratory results. Thyrotoxic group Control group (n= 22) (n= 20) p Age (years) 24.0 ± ± a FT3 (pg/ml) 3.92 ± ± 0.38 < b FT4 (ng/ml) 1.40 ± ± b TSH (µu/ml) 0.03 ± ± 1.09 < b Vitamin B 12 (pg/ml) ± ± b Folate (ng/ml) 8.8 ± ± b thcy (µmol/ml) 9.6 ± ± 1.9 < b Albumin (g/l) 35.0 ± ± b TSH: thyro id-sti mu la ting hor mo ne; FT3: fre e tri i o doth yro ni ne; FT4: fre e thyro xi ne; TR- Ab: an ti-tsh re cep tor an ti body; thcy: to tal ho mocy ste i ne a Stu dent s t-test, b Mann-Whit ney U test. TABLE 2: Correlation coefficients and significance levels between the age, thyroid functions and autoantibodies, vitamin B 12, folate and thcy levels Total homocysteine Variables rho p Age (years) FT3 (pg/ml) FT4 (ng/dl) TSH (µiu/ml) < TR-Ab (IU/L) TPO-Ab (IU/L) Tg-Ab (IU/L) Folate (ng/ml) Vit B 12 (pg/ml) Albumin (g/l) TSH: thyro id sti mu la ting hor mo ne; FT3: fre e tri i o doth yro ni ne; ft4: fre e thyro xin; TR-Ab: an ti-tsh re cep tor an ti body; TPO-Ab: an ti-thyro pe ro xi da se an ti body ; Tg-Ab: an ti-thyrog - lo bu lin an ti body. in pregnancy, decrease in albumin level was related to decreased B 12 vitamin and folate level and physiological pregnancy hemodilution. 18,19 There are contradictory conclusions about the homocysteine levels of the hyper-hypothyroidy patients. Generally serum homocysteine levels were found normal or high in hypothyroidism and normal or low in hyperthyroidism In animal studies, however, serum homocysteine levels were high in hyperthyroidism. 20,21 The mechanism of the homocysteine increase in hypothyroid patients is not entirely clear, but studies suggest it may be related to decreased renal excretion of homocysteine due to decreased glomerular filtration rate or decreased activity enzymes involved in homocystein metabolism. 18,22 The mechanism of the increase in homocysteine levels in hyperthyroidism seems to be more complicated. Colleran et al. found in their study that there was an increase in homocysteine levels in thyrotoxic individuals with newly diagnosed Graves disease. 23 It is known that Graves disease may be accompanied by pernicious anemia as well as other autoimmune diseases. In this case, there may be absolute vitamin B 12 deficiency and due homocysteine increase. However, in this study, none of the patients had low vitamin B 12 level. Although there was no vitamin B 12 deficiency in the Turkiye Klinikleri J Gynecol Obst 2009;19(3) 157

4 Dilek BERKER et al EVALUATION OF SERUM HOMOCYSTEINE LEVELS IN PREGNANT PATIENTS WITH GRAVES' DISEASE mentioned study, positive correlation was found with homocysteine levels in methylmalonic acid levels which is the marker of vitamin B 12 deficiency. 23 Also in this study, which revealed similar results, although there was no absolute vitamin B 12 deficiency, it was considered that potential functional vitamin B 12 deficiency may be the cause for the increase in homocysisteine levels. It has also been stated that there may be a homocysteine increase in autoimmune diseases in line with inflammatory activation, as well as it can contrarily act as immune-stimulating molecule in homocysteine. 24 It was considered that another reason for high homocysteine in our patients with hyperthyroidism depending on Graves disease can be the bi-directional relationship between autoimmune diseases and homocysteine. There are numerous reports on experimental studies showing that FT4 and hyperthyroidism affect folate metabolism and the enzymes involved. The observations that methylenetetrahydrofolate reductase is increased in hyperthyroidism and decreased in hypothyroidism may be relevant for the relation between the thcy level and thyroid status. 25 This enzyme is responsible for the formation of 5-methyltetrahydrofolate, which functions as methyl donor during remethylation of homocysteine to methionine. 26 During endemic goiter in humans, plasma thcy increases, whereas most other amino acids except for methionine decrease. 22 Turkey is in endemic goiter region. Yet it is considered that the reason why pregnant women with Graves disease have high homocystein levels than those without, lies not in endemic goiter but thyrotoxicosis, autoimmune or functional vit B 12 deficiency. In this study, serum thcy levels were higher in thyrotoxic pregnant women than normal pregnant women. However sufficient information has not been achieved concerning the homocysteine in pregnant women with GD. As it is known that hyperhomocysteine causes neural tube defects, repeated miscarriages, abruptio placentae, fetal death, preeclampsia and intrauterine growth retardation in pregnant women. It should be borne in mind that homocysteine levels can be high in risky pregnancies accompanied by Graves disease and can cause complications, as there is no clear data available so far on changes in homocysteine levels in pregnant women with Graves disease. In conclusion, there is a need for large scale studies comparing pre- and post-treatment homocysteine levels in hyperthyroid cases of pregnant and non-pregnant individuals. 1. Sun da ram V, Han na AN, Ko ne ru L, New man HA, Fal ko JM. Both hypoth yro i dism and hyperth yro i dism en han ce low den sity li pop ro te - in oxi da ti on. J Clin En doc ri nol Me tab 1997; 82(10): Le ung AS, Mil lar LK, Ko o nings PP, Mon to ro M, Mest man JH. Pe ri na tal out co me in hypoth - yro id preg nan ci es. Obs tet Gyne col 1993; 81(3): Mil lar LK, Wing DA, Le ung AS, Ko o nings PP, Mon to ro MN, Mest man JH. Low birth we ight and pre ec lamp si a in preg nan ci es comp li ca ted by hyperth yro i dism. Obs tet Gyne col 1994; 84(6): Shef fi eld JS, Cun ning ham FG. Thyro to xi co sis and he art fa i lu re that comp li ca te preg nancy. Am J Obs tet Gyne col 2004;190(1): REFERENCES 5. Da vis LE, Lu cas MJ, Han kins GD, Ro ark ML, Cun ning ham FG. Thyro to xi co sis comp li ca ting preg nancy. Am J Obs tet Gyne col 1989; 160(1): Barbé F, Kle in M, Chan go A, Frémont S, Gérard P, Wery ha G, et al. Ho mocy ste i ne, fola te, vi ta min B12, and trans co ba la mins in pati ents un der go ing suc ces si ve hypo- and hyperth yro id sta tes. J Clin En doc ri nol Me tab 2001;86(4): Ned rebø BG, Erics son UB, Nygård O, Ref sum H, Ue land PM, Aak va ag A, et al. Plas ma to tal ho mocy ste i ne le vels in hyperth yro id and hypoth yro id pa ti ents. Me ta bo lism 1998;47(1): Ata bek ME, Pir gon O, Er kul I. Plas ma ho mocy ste i ne con cen tra ti ons in ado les cents with subc li ni cal hypoth yro i dism. J Pe di atr En doc ri - nol Me tab 2003;16(9): Di ek man MJ, van der Put NM, Blom HJ, Tijs - sen JG, Wi er sin ga WM. De ter mi nants of chan - ges in plas ma ho mocy ste i ne in hyperth yroi dism and hypoth yro i dism. Clin En doc ri nol (Oxf) 2001;54(2): De mir bas B, Oz ka ya M, Ca kal E, Cul ha C, Gul ce lik N, Koc G, et al. Plas ma ho mocy ste i - ne le vels in hyperth yro id pa ti ents. En docr J 2004;51(1): Han key GJ, Ei kel bo om JW. Ho mocy ste i ne and vas cu lar di se a se. Lan cet 1999;354 (9176): van Gul de ner C, Ro bin son K. Ho mocy ste i ne and re nal di se a se. Se min Thromb He most 2000;26(3): Turkiye Klinikleri J Gynecol Obst 2009;19(3)

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