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doi:10.1111/jog.12482
J. Obstet. Gynaecol. Res. Vol. 40, No. 12: 2201–2203, December 2014
Case of radioactive iodine exposure during pregnancy Hisanobu Sadakata1, Hiromitsu Shinozaki2, Tetsuya Higuchi3 and Takashi Minegishi1 Departments of 1Obstetrics and Gynecology and 3Diagnostic Radiology and Nuclear Medicine, Gunma University Graduate School of Medicine, and 2Gunma University Graduate School of Health Science, Gunma, Japan
Abstract A 43-year-old woman (gravida 0, para 0) was diagnosed with thyroid carcinoma and had been receiving radioactive iodine for remnant ablation. Eventually, her pregnant status became apparent; during radiation, she was at 5 gestational weeks. She decided to continue the pregnancy and delivered a boy of 2362 g at 37 gestational weeks. The infant did not present thyroid dysfunction or developmental abnormalities at 2 months of age. The patient was in the early pregnancy stage during radiation, so the fetus did not develop radiationrelated damage of the thyroid gland because at this stage, the fetal thyroid does not concentrate iodine. Although the mother had received radioactive iodine during the critical organogenesis period, the fetus did not develop teratogenicity because the radiation was administered at the borderline threshold for teratogenicity. This case suggests the importance of iodine thyroid absorption when considering radiation-related damage to the fetal thyroid gland during early pregnancy. Key words: congenital abnormalities, fetal thyroid function, iodine radioisotopes, maternal exposure, radiation effect.
Introduction Radiation can affect the human body through external and internal exposure, and its effect depends on the affinity of each nuclide for various organs. In particular, in cases of radioactive iodine exposure to the thyroid gland, the iodine accumulates in the thyroid gland. A similar influence is expected on a fetus when a pregnant woman is exposed to radiation. We report the case of a woman who received radioactive iodine medication without knowledge of her pregnancy.
Case Report A 43-year-old woman, gravida 0, para 0, with a history of type 2 diabetes and hyperuricemia was diagnosed with thyroid carcinoma and had undergone total thyroidectomy. The lymph node pathology was positive for metastasis of carcinoma cells, so she needed radiation therapy for remnant ablation.
She was administered 50 mCi of I-131 exposure (1.85 × 103 MBq) for remnant ablation 5 months after the surgery. Then, she was on thyroid hormone replacement therapy with 150 μg of levothyroxine per day. She also took 2 mg of glimepiride and 250 mg of metformin hydrochloride per day for diabetes and 50 mg of benzbromarone per day for hyperuricemia. The patient assumed that she was not pregnant as her last menstruation had occurred about 2 months before the radiation therapy, and her menstrual cycle was originally irregular and infrequent. After radiation therapy, she continuously felt nauseous, but she thought it was a side-effect of the radiation. She decided to take a pregnancy test, and her urine was positive for human chorionic gonadotrophin, indicating pregnancy. Nine weeks after the radiation therapy, a medical practitioner determined that she had completed 15 weeks of gestation. The radiologist was informed of her pregnancy to investigate the possible effects of radiation on her fetus.
Received: November 10 2013. Accepted: April 23 2014. Reprint request to: Dr Hisanobu Sadakata, Department of Obstetrics and Gynecology, Gunma University Graduate School of Medicine, 3-39-15, Showa-machi, Maebashi, Gunma 371-8511, Japan. Email: [email protected]
© 2014 The Authors Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology
2201
H. Sadakata et al.
According to the International Commission on Radiological Protection (ICRP) recommendations, the total absorbed dose of radiation by the fetus, from external exposure throughout pregnancy, is estimated to be 50–100 μGy per one MBq of administered I-131.1 Therefore, in the present case, the fetus absorbed an estimated dose of 92.5–185 mGy of radiation through external exposure. Regarding the teratogenicity of radiation, up to 100–500 mGy of radiation has been reported as safe for the fetus;2,3 however, other reports state that 100 mGy of radiation at 4–10 weeks of gestational age is sufficient to induce fetus deformity.4 Regarding internal exposure, the fetal thyroid can absorb 0.5–1.1 Gy of radiation per one MBq of administered I-131.1 Therefore, in the present case, the fetus absorbed an estimated dose of 925–2035 Gy through internal exposure. In adults, the threshold dose of radiation that induces hypothyroidism is approximately 20–50 Gy, and >200 Gy of radiation is known to induce acute radiation thyroiditis.5 In contrast, a fetus is found to have greater sensitivity to radiation than an adult.6 Therefore, the dose of radiation absorbed by the fetus in the present case is considered sufficient to have caused fetal thyroid gland dysfunction. Ten weeks after the radiation therapy, the patient visited our outpatient department of obstetrics and gynecology. The sonographic assessment indicated that the fetus was at 15 weeks and 5 days of gestational age, and the estimated date of confinement was found to be 5 weeks and 3 days of gestational age at the time of radiation therapy. The patient discussed the continuation of pregnancy with her family and finally decided to give birth. She stopped oral hypoglycemic drugs and started subcutaneous insulin injection. We suggested umbilical cord blood sampling for the evaluation of fetal thyroid function, but she declined. Finally, she delivered a 2362-g baby boy at 37 weeks of gestation by cesarean section. The infant had no abnormalities, and his laboratory data were normal. The thyroid function of the infant (reference range) was as follows: thyroid-stimulating hormone levels (mIU/L) were 5.92 (3–22) at day 0, 2.91 (1–19) at day 5, and 2.37 (1–19) at day 28 and free thyroxine levels (pmol/L) were 15.45 at day 0, 26.64 at day 5, and 16.73 (7.47–21.1) at day 28. Thus, the infant’s thyroid function test results revealed that the hormones were within their normal ranges after radiation exposure. The infant showed no developmental abnormalities at 2 months of age.
2202
Discussion We present the case of a pregnant woman whose fetus was exposed to an estimated 92.5–185 mGy of external radiation and 925–2035 Gy of internal radiation. However, she delivered a child with no congenital abnormality. During human embryogenesis, the thyroid gland is developed, and it starts concentrating iodine and secreting iodotyrosine from 10–12 weeks of gestational age.7,8 We suspect that in the present case, the fetal thyroid did not trap any I-131 because at the time of radiation, it did not concentrate iodine. On the other hand, with regard to direct exposure, the threshold value at which the absorbed dose of radiation induces fetal teratogenicity is approximately 100 mGy.1 In the present case, the time of radiation exposure (at the gestational age of 5 weeks and 3 days) was within the organogenesis period. The estimated dose absorbed by the fetus due to external exposure is believed to be similar to the borderline value required to induce teratogenicity. However, the fetus was not affected by radiation in the present case. According to the ICRP Publ. 84,1 animal data suggest that the child’s probability of not developing any malformations during the organogenesis period is nearly 97% when the dose absorbed by the fetus is 100 mGy. In the present case, the estimated dose absorbed by the fetus was 92.5–185 mGy; therefore, the probability of not developing any malformations may be slightly lower than 97%. We should also note that the patient had undergone thyroidectomy for thyroid carcinoma; therefore, I-131 could have been concentrated in the remnant thyroid tissue and metastatic focus and remained in the mother’s body. Hence, the fetus may have been exposed to I-131 for a certain amount of time after the administration of I-131. However, the ability of thyroid cancer cells to take up I-131 is much lower than that of healthy cells;9 therefore, it is unlikely that the radiation dose absorbed by the fetus was sufficiently high to induce malformation, even if remnant thyroid tissue and metastasis were present in the current case. There are several reports on the effects of maternal exposure to radioactive iodine. Kurtog˘lu et al. reported a case in which an infant developed congenital hypothyroidism because the mother had received 20 mCi of radioactive iodine at 12 weeks of gestational age.8 In another report, the infant whose mother had received 103 mCi of I-131 at 10 weeks of gestational age had thyroid tissue destruction.10 These reports suggest that
© 2014 The Authors Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology
Radiation during pregnancy
maternal I-131 exposure after 10 weeks of gestational age could negatively affect the fetus because at this time, as the thyroid starts to accumulate iodine. In contrast, a previous study has reported the case of an infant who had normal thyroid function, even though the mother had received 542 MBq (equivalent to 14.7 mCi) radiation at 8 weeks of gestational age.11 The estimated fetal absorbed dose was 45 mGy, which was lower than the threshold at which fetal damage occurs, but if the fetal uptake of iodine has begun, the estimated fetal absorbed dose is 271–596 Gy, which is sufficient to cause fetal thyroid damage.1,6 The present case suggests that the fetal thyroid may not be affected by maternal I-131 exposure before the thyroid gland starts accumulating iodine. There are several reports on prenatal diagnosis and treatment of fetal hypothyroidism. Samples of fetal blood are taken by cordocentesis to measure fetal thyroid function. If the fetus is diagnosed with hypothyroidism, levothyroxine is infused weekly into the amniotic cavity.12 In the present case, we did not perform the procedure because the patient did not consent to this. It is generally known that thyroxine can cross the placental barrier; however, it is unknown if the maternal supplement of levothyroxine has a supportive effect on the fetus. There are other effects of fetal radiation. Mental retardation could occur in the child, when the absorbed dose of radiation is greater than 200 mGy after 8 weeks of gestation.13 The risk of carcinogenesis of the fetus increases when the absorbed dose of radiation is 10 mGy during embryogenesis.14 Therefore, the infant should be followed up longitudinally to assess mental development and detect carcinogenesis. Even though our patient received radiation therapy during her pregnancy, we conclude that radiationinduced thyroid dysfunction did not occur in the fetus because she had received radiation during the early stages of her pregnancy. This case suggests the importance of iodine thyroid absorption when considering radiation-related damage of the fetal thyroid gland during the early stage of pregnancy. Written informed consent was obtained from the patient for publication of this case report.
References 1. International Commission on Radiological Protection. Pregnancy and medical radiation. Ann ICRP 2000; 30: 1–43. 2. De Santis M, Di Gianantonio E, Straface G et al. Ionizing radiations in pregnancy and teratogenesis: A review of literature. Reprod Toxicicol 2005; 20: 323–329. 3. Brent RL. Utilization of developmental basic science principles in the evaluation of reproductive risks from pre- and postconception environmental radiation exposures. Teratology 1999; 59: 182–204. 4. Streffer C, Shore R, Konermann G et al. Biological effects after prenatal irradiation (embryo and fetus). A report of the International Commission on Radiological Protection. Ann ICRP 2003; 33: 5–206. 5. Nonstochastic effects of ionizing radiation. Ann ICRP 1984; 14: 1–33. 6. Ogris E. Exposure to radioactive iodine in pregnancy: Significance for mother and child. Acta Med Austriaca 1997; 24: 150– 153. 7. Fisher DA, Klein AH. Thyroid development and disorders of thyroid function in the newborn. N Engl J Med 1981; 304: 702–712. 8. Kurtog˘lu S, Akin MA, Daar G et al. Congenital hypothyroidism due to maternal radioiodine exposure during pregnancy. J Clin Res Pediatr Endocrinol 2012; 4: 111–113. 9. Kukulska A, Krajewska J, Gawkowska-Suwin´ska M et al. Radioiodine thyroid remnant ablation in patients with differentiated thyroid carcinoma (DTC): Prospective comparison of long-term outcomes of treatment with 30, 60 and 100 mCi. Thyroid Res 2010; 3: 9. 10. Richards GR, Brewer ED, Conley SB, Saldana LR. Combined hypothyroidism in an infant after maternal 131I administration. J Pediatr 1981; 99: 141–143. 11. Evans PM, Webster J, Evans WD, Bevan JS, Scanlon MF. Radioiodine treatment in unsuspected pregnancy. Clin Endocrinol (Oxf) 1998; 48: 281–283. 12. Abuhamad AZ, Fisher DA, Warsof SL et al. Antenatal diagnosis and treatment of fetal goitrous hypothyroidism: Case report and review of the literature. Ultrasound Obstet Gynecol 1995; 6: 368–371. 13. Stabin MG, Watson EE, Marcus CS, Salk RD. Radiation dosimetry for the adult female and fetus from iodine-131 administration in hyperthyroidism. J Nucl Med 1991; 32: 808– 813. 14. Kusama T, Ota K. Radiological protection for diagnostic examination of pregnant women. Congenit Anom (Kyoto) 2002; 42: 10–14.
Disclosure The authors have no conflicts of interest to disclose.
© 2014 The Authors Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology
2203
Copyright of Journal of Obstetrics & Gynaecology Research is the property of WileyBlackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
doi:10.1111/jog.12482
J. Obstet. Gynaecol. Res. Vol. 40, No. 12: 2201–2203, December 2014
Case of radioactive iodine exposure during pregnancy Hisanobu Sadakata1, Hiromitsu Shinozaki2, Tetsuya Higuchi3 and Takashi Minegishi1 Departments of 1Obstetrics and Gynecology and 3Diagnostic Radiology and Nuclear Medicine, Gunma University Graduate School of Medicine, and 2Gunma University Graduate School of Health Science, Gunma, Japan
Abstract A 43-year-old woman (gravida 0, para 0) was diagnosed with thyroid carcinoma and had been receiving radioactive iodine for remnant ablation. Eventually, her pregnant status became apparent; during radiation, she was at 5 gestational weeks. She decided to continue the pregnancy and delivered a boy of 2362 g at 37 gestational weeks. The infant did not present thyroid dysfunction or developmental abnormalities at 2 months of age. The patient was in the early pregnancy stage during radiation, so the fetus did not develop radiationrelated damage of the thyroid gland because at this stage, the fetal thyroid does not concentrate iodine. Although the mother had received radioactive iodine during the critical organogenesis period, the fetus did not develop teratogenicity because the radiation was administered at the borderline threshold for teratogenicity. This case suggests the importance of iodine thyroid absorption when considering radiation-related damage to the fetal thyroid gland during early pregnancy. Key words: congenital abnormalities, fetal thyroid function, iodine radioisotopes, maternal exposure, radiation effect.
Introduction Radiation can affect the human body through external and internal exposure, and its effect depends on the affinity of each nuclide for various organs. In particular, in cases of radioactive iodine exposure to the thyroid gland, the iodine accumulates in the thyroid gland. A similar influence is expected on a fetus when a pregnant woman is exposed to radiation. We report the case of a woman who received radioactive iodine medication without knowledge of her pregnancy.
Case Report A 43-year-old woman, gravida 0, para 0, with a history of type 2 diabetes and hyperuricemia was diagnosed with thyroid carcinoma and had undergone total thyroidectomy. The lymph node pathology was positive for metastasis of carcinoma cells, so she needed radiation therapy for remnant ablation.
She was administered 50 mCi of I-131 exposure (1.85 × 103 MBq) for remnant ablation 5 months after the surgery. Then, she was on thyroid hormone replacement therapy with 150 μg of levothyroxine per day. She also took 2 mg of glimepiride and 250 mg of metformin hydrochloride per day for diabetes and 50 mg of benzbromarone per day for hyperuricemia. The patient assumed that she was not pregnant as her last menstruation had occurred about 2 months before the radiation therapy, and her menstrual cycle was originally irregular and infrequent. After radiation therapy, she continuously felt nauseous, but she thought it was a side-effect of the radiation. She decided to take a pregnancy test, and her urine was positive for human chorionic gonadotrophin, indicating pregnancy. Nine weeks after the radiation therapy, a medical practitioner determined that she had completed 15 weeks of gestation. The radiologist was informed of her pregnancy to investigate the possible effects of radiation on her fetus.
Received: November 10 2013. Accepted: April 23 2014. Reprint request to: Dr Hisanobu Sadakata, Department of Obstetrics and Gynecology, Gunma University Graduate School of Medicine, 3-39-15, Showa-machi, Maebashi, Gunma 371-8511, Japan. Email: [email protected]
© 2014 The Authors Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology
2201
H. Sadakata et al.
According to the International Commission on Radiological Protection (ICRP) recommendations, the total absorbed dose of radiation by the fetus, from external exposure throughout pregnancy, is estimated to be 50–100 μGy per one MBq of administered I-131.1 Therefore, in the present case, the fetus absorbed an estimated dose of 92.5–185 mGy of radiation through external exposure. Regarding the teratogenicity of radiation, up to 100–500 mGy of radiation has been reported as safe for the fetus;2,3 however, other reports state that 100 mGy of radiation at 4–10 weeks of gestational age is sufficient to induce fetus deformity.4 Regarding internal exposure, the fetal thyroid can absorb 0.5–1.1 Gy of radiation per one MBq of administered I-131.1 Therefore, in the present case, the fetus absorbed an estimated dose of 925–2035 Gy through internal exposure. In adults, the threshold dose of radiation that induces hypothyroidism is approximately 20–50 Gy, and >200 Gy of radiation is known to induce acute radiation thyroiditis.5 In contrast, a fetus is found to have greater sensitivity to radiation than an adult.6 Therefore, the dose of radiation absorbed by the fetus in the present case is considered sufficient to have caused fetal thyroid gland dysfunction. Ten weeks after the radiation therapy, the patient visited our outpatient department of obstetrics and gynecology. The sonographic assessment indicated that the fetus was at 15 weeks and 5 days of gestational age, and the estimated date of confinement was found to be 5 weeks and 3 days of gestational age at the time of radiation therapy. The patient discussed the continuation of pregnancy with her family and finally decided to give birth. She stopped oral hypoglycemic drugs and started subcutaneous insulin injection. We suggested umbilical cord blood sampling for the evaluation of fetal thyroid function, but she declined. Finally, she delivered a 2362-g baby boy at 37 weeks of gestation by cesarean section. The infant had no abnormalities, and his laboratory data were normal. The thyroid function of the infant (reference range) was as follows: thyroid-stimulating hormone levels (mIU/L) were 5.92 (3–22) at day 0, 2.91 (1–19) at day 5, and 2.37 (1–19) at day 28 and free thyroxine levels (pmol/L) were 15.45 at day 0, 26.64 at day 5, and 16.73 (7.47–21.1) at day 28. Thus, the infant’s thyroid function test results revealed that the hormones were within their normal ranges after radiation exposure. The infant showed no developmental abnormalities at 2 months of age.
2202
Discussion We present the case of a pregnant woman whose fetus was exposed to an estimated 92.5–185 mGy of external radiation and 925–2035 Gy of internal radiation. However, she delivered a child with no congenital abnormality. During human embryogenesis, the thyroid gland is developed, and it starts concentrating iodine and secreting iodotyrosine from 10–12 weeks of gestational age.7,8 We suspect that in the present case, the fetal thyroid did not trap any I-131 because at the time of radiation, it did not concentrate iodine. On the other hand, with regard to direct exposure, the threshold value at which the absorbed dose of radiation induces fetal teratogenicity is approximately 100 mGy.1 In the present case, the time of radiation exposure (at the gestational age of 5 weeks and 3 days) was within the organogenesis period. The estimated dose absorbed by the fetus due to external exposure is believed to be similar to the borderline value required to induce teratogenicity. However, the fetus was not affected by radiation in the present case. According to the ICRP Publ. 84,1 animal data suggest that the child’s probability of not developing any malformations during the organogenesis period is nearly 97% when the dose absorbed by the fetus is 100 mGy. In the present case, the estimated dose absorbed by the fetus was 92.5–185 mGy; therefore, the probability of not developing any malformations may be slightly lower than 97%. We should also note that the patient had undergone thyroidectomy for thyroid carcinoma; therefore, I-131 could have been concentrated in the remnant thyroid tissue and metastatic focus and remained in the mother’s body. Hence, the fetus may have been exposed to I-131 for a certain amount of time after the administration of I-131. However, the ability of thyroid cancer cells to take up I-131 is much lower than that of healthy cells;9 therefore, it is unlikely that the radiation dose absorbed by the fetus was sufficiently high to induce malformation, even if remnant thyroid tissue and metastasis were present in the current case. There are several reports on the effects of maternal exposure to radioactive iodine. Kurtog˘lu et al. reported a case in which an infant developed congenital hypothyroidism because the mother had received 20 mCi of radioactive iodine at 12 weeks of gestational age.8 In another report, the infant whose mother had received 103 mCi of I-131 at 10 weeks of gestational age had thyroid tissue destruction.10 These reports suggest that
© 2014 The Authors Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology
Radiation during pregnancy
maternal I-131 exposure after 10 weeks of gestational age could negatively affect the fetus because at this time, as the thyroid starts to accumulate iodine. In contrast, a previous study has reported the case of an infant who had normal thyroid function, even though the mother had received 542 MBq (equivalent to 14.7 mCi) radiation at 8 weeks of gestational age.11 The estimated fetal absorbed dose was 45 mGy, which was lower than the threshold at which fetal damage occurs, but if the fetal uptake of iodine has begun, the estimated fetal absorbed dose is 271–596 Gy, which is sufficient to cause fetal thyroid damage.1,6 The present case suggests that the fetal thyroid may not be affected by maternal I-131 exposure before the thyroid gland starts accumulating iodine. There are several reports on prenatal diagnosis and treatment of fetal hypothyroidism. Samples of fetal blood are taken by cordocentesis to measure fetal thyroid function. If the fetus is diagnosed with hypothyroidism, levothyroxine is infused weekly into the amniotic cavity.12 In the present case, we did not perform the procedure because the patient did not consent to this. It is generally known that thyroxine can cross the placental barrier; however, it is unknown if the maternal supplement of levothyroxine has a supportive effect on the fetus. There are other effects of fetal radiation. Mental retardation could occur in the child, when the absorbed dose of radiation is greater than 200 mGy after 8 weeks of gestation.13 The risk of carcinogenesis of the fetus increases when the absorbed dose of radiation is 10 mGy during embryogenesis.14 Therefore, the infant should be followed up longitudinally to assess mental development and detect carcinogenesis. Even though our patient received radiation therapy during her pregnancy, we conclude that radiationinduced thyroid dysfunction did not occur in the fetus because she had received radiation during the early stages of her pregnancy. This case suggests the importance of iodine thyroid absorption when considering radiation-related damage of the fetal thyroid gland during the early stage of pregnancy. Written informed consent was obtained from the patient for publication of this case report.
References 1. International Commission on Radiological Protection. Pregnancy and medical radiation. Ann ICRP 2000; 30: 1–43. 2. De Santis M, Di Gianantonio E, Straface G et al. Ionizing radiations in pregnancy and teratogenesis: A review of literature. Reprod Toxicicol 2005; 20: 323–329. 3. Brent RL. Utilization of developmental basic science principles in the evaluation of reproductive risks from pre- and postconception environmental radiation exposures. Teratology 1999; 59: 182–204. 4. Streffer C, Shore R, Konermann G et al. Biological effects after prenatal irradiation (embryo and fetus). A report of the International Commission on Radiological Protection. Ann ICRP 2003; 33: 5–206. 5. Nonstochastic effects of ionizing radiation. Ann ICRP 1984; 14: 1–33. 6. Ogris E. Exposure to radioactive iodine in pregnancy: Significance for mother and child. Acta Med Austriaca 1997; 24: 150– 153. 7. Fisher DA, Klein AH. Thyroid development and disorders of thyroid function in the newborn. N Engl J Med 1981; 304: 702–712. 8. Kurtog˘lu S, Akin MA, Daar G et al. Congenital hypothyroidism due to maternal radioiodine exposure during pregnancy. J Clin Res Pediatr Endocrinol 2012; 4: 111–113. 9. Kukulska A, Krajewska J, Gawkowska-Suwin´ska M et al. Radioiodine thyroid remnant ablation in patients with differentiated thyroid carcinoma (DTC): Prospective comparison of long-term outcomes of treatment with 30, 60 and 100 mCi. Thyroid Res 2010; 3: 9. 10. Richards GR, Brewer ED, Conley SB, Saldana LR. Combined hypothyroidism in an infant after maternal 131I administration. J Pediatr 1981; 99: 141–143. 11. Evans PM, Webster J, Evans WD, Bevan JS, Scanlon MF. Radioiodine treatment in unsuspected pregnancy. Clin Endocrinol (Oxf) 1998; 48: 281–283. 12. Abuhamad AZ, Fisher DA, Warsof SL et al. Antenatal diagnosis and treatment of fetal goitrous hypothyroidism: Case report and review of the literature. Ultrasound Obstet Gynecol 1995; 6: 368–371. 13. Stabin MG, Watson EE, Marcus CS, Salk RD. Radiation dosimetry for the adult female and fetus from iodine-131 administration in hyperthyroidism. J Nucl Med 1991; 32: 808– 813. 14. Kusama T, Ota K. Radiological protection for diagnostic examination of pregnant women. Congenit Anom (Kyoto) 2002; 42: 10–14.
Disclosure The authors have no conflicts of interest to disclose.
© 2014 The Authors Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology
2203
Copyright of Journal of Obstetrics & Gynaecology Research is the property of WileyBlackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
