Incidence Of Primary Hypothyroidism Research Articles

Thyroid Function after Postoperative Radiation Therapy in Patients with Breast Cancer

Objective:The aim of this study was to assess thyroid function in breast cancer patients exposed to therapeutic external beam radiation. The focus was on possible progressive changes and any relationships between the incidence of primary hypothyroidism, the time required to become hypothyroid, and factors such as chemotherapy, hormonotherapy and immunotherapy.Materials and Methods:Seventy females undergoing 3D conformal and IMRT radiation therapy for breast cancers were enrolled in a non-randomized prospective study. The patients was divided into two groups: those after mastectomy or breast conserving surgery (BCS) were irradiated to a scar of the chest wall/breast and the ipsilateral supraclavicular and the axillary areas (supraclavicular radiotherapy group - SC-RT group – 32 patients) and the control group receiving adjuvant chest wall/breast RT only (BCT group - 38 patients). The total doses were 50.0 to 70 Gy in 5 to 7 weeks. The median follow-up term was 24 months (range, 1–40 months). Thyroid function was evaluated by measuring thyroid stimulating hormone (TSH), free thyroxine (fT4), and free triiodothyronine (fT3) levels. The minimum, maximum and mean thyroid gland doses for 20 Gy (V20) were calculated for all patients.Results:Statistically significant results were obtained for the SC-RT group. Two yearsa fter the end of RT the chance of an event was increased in 6% of the population (p=0.009) in the SC-RT group. In the BCT group no significance was noted. No statistically significant differences were found for V20, chemio-, immunotherapy and hormonotherapy or Ki67 values (p=0.12). No significant results were obtained for development of hypothyroidism and clinical factors (age, thyroid volume, treatment modalities).Conclusion:Radiotherapy is associated with a higher incidence of thyroid toxicity in breast cancer patients. Routine thyroid function monitoring should be recommended in such cases.

Incidence of Sunitinib induced thyroid dysfunction in renal cell carcinoma: a pilot retrospective audit

Primary hypothyroidism is a common adverse effect of TKI therapy. The incidence of primary hypothyroidism in this cohort was 20% and is similar to hypothyroidism rates in published data from Sunitinib studies (14-46%). There appeared to be a significant delay between the diagnosis of overt primary hypothyroidism and the start of LT4 therapy. Regular pre-cycle TFT checks and close liaison with Endocrinology will help reduce morbidity from delayed diagnosis and treatment of hypothyroidism. 10% 3%

The relationship between thyroid dose and diagnosis of primary hypothyroidism in pediatric brain tumor patients receiving craniospinal irradiation

The aim of this work is to determine if a relationship exists between thyroid dose and incidence of primary hypothyroidism (PH) in children undergoing craniospinal irradiation (CSI). A total of 22 patients received CSI with evaluable thyroid dose information. All patients received concurrent chemotherapy and 21 patients (95%) received adjuvant chemotherapy. Median follow-up was 42.9 months. The incidence of PH in our cohort was 59% at a median time after radiotherapy of 3.5 years (range: 8 months to 7.5 years). Mean thyroid dose appeared to best predict for PH, with a median of 2080 cGy for patients with PH versus 1736 cGy for children without PH (p=0.057). There was no association between the rate of PH and sex, age, CSI dose, minimum thyroid dose and maximum thyroid dose. A relationship may exist between the mean thyroid dose and incidence of PH in patients undergoing CSI. Thus, new strategies to protect the thyroid gland may be warranted.

Incidence of primary hypothyroidism in patients exposed to therapeutic external beam radiation, where radiation portals include a part or whole of the thyroid gland

Introduction:Hypothyroidism is a known consequence of external-beam radiotherapy to the neck encompassing a part or whole of the thyroid gland. In this non-randomized prospective study, we have tried to evaluate the response of the thyroid gland to radiation by assessing thyroid function before irradiation and at regular intervals after irradiation.Aims and Objectives:The aim of this study were to assess in the cancer patients, who were exposed to the therapeutic external beam radiation, where radiation portals include a part or whole of the thyroid gland: the incidence of primary hypothyroidism, the time required to become hypothyroid, any relation between the total dose for the development of hypothyroidism, and whether there are any patient or treatment-related factors that are predictive for the development of hypothyroidism, including the use of concurrent chemotherapy.Materials and Methods:This non-randomized, prospective study was conducted for a period of 2 years in which thyroid function was assessed in 59 patients (cases) of head and neck cancer, breast cancer, lymphoma patients and other malignancies, who had received radiotherapy to the neck region. 59 euthyroid healthy patients (controls) were also taken, who had not received the neck irradiation. These patients/controls were assessed periodically for 2 years.Results:The incidence of hypothyroidism after external beam radiation therapy (EBRT) to neck where radiation portals include part or whole of the thyroid gland was 16.94%, seven cases had subclinical hypothyroidism (11.86%) and three cases had clinical hypothyroidism (5.08%). Mean time for development of hypothyroidism was 4.5 months. There was no effect of age, gender, primary tumor site, radiation dose and chemotherapy, whether neoadjuvant or concurrent with the development of hypothyroidism.Conclusion:In summary, we found that thyroid dysfunction is a prevalent, yet easily treatable source of morbidity in patients undergoing radiation therapy to neck where radiation portals include a part or whole of the thyroid gland.

Survey of neonatal screening for primary hypothyroidism in England, Wales, and Northern Ireland 1982-4

National screening for congenital hypothyroidism was established in the United Kingdom in 1982. During 1982-4, 488 infants with primary congenital hypothyroidism were detected by the 25 regional screening laboratories in England, Wales, and Northern Ireland. In addition, one infant had signs of cretinism at birth and was investigated before the screening test was done and four infants were known to have been missed by the screening programme; among these four infants the initial thyroid stimulating hormone concentrations were normal in two with inherited defects of synthesis of thyroxine, not measured in one, and false negative in one. The overall incidence of primary hypothyroidism was 1:3937 births (boys 1:6640, girls 1:2756). The incidence seemed to be reduced in infants born to black mothers (two cases only) and increased in those born to Asian mothers (61 cases). Congenital anomalies other than those of the thyroid glands were reported in 36 children (7%), and 15 (3%) died from various causes before the age of 4. Infants who were considered to show unequivocal evidence of hypothyroidism started treatment at a median age of 17 days (5th and 95th centiles 10 and 42 days) compared with a median age of 14 days (5th and 95th centiles 9 and 21 days) for infants with classic phenylketonuria also detected by national screening.

Thyroid and Pituitary Function Following Allogeneic Bone Marrow Transplantation

Thyroid function was evaluated in 13 consecutive patients with chronic myelogenous leukemia to verify in allogeneic bone marrow transplantation if the fractionated irradiation protocol with low dose rate, previously applied to reduce the damage to various organs, also prevents the 43% incidence of primary hypothyroidism that occurs after the administration of single dose with higher dose rate. Following bone marrow transplantation, decreased plasma levels of total thyroxine and triiodothyronine and impaired response of thyrotropic cells to thyrotropin-releasing hormone were observed. These alterations reverted to normal in nine months and none of the patients was hypothyroid at the end of follow-up. The damage to thyrotropic cells appears to be selective because the secretion of prolactin was not impaired and that of gonadotropins even increased, as a consequence of gonadal failure. Longer follow-up is needed to determine if this irradiation protocol, which prevents the complication of permanent primary hypothyroidism and does not cause any destruction of thyroid cells, may increase the risk of irradiation-related thyroid tumors.

Congenital hypothyroidism. Clinical and laboratory characteristics in infants detected by neonatal screening.

The clinical and laboratory characteristics of infants with neonatal hypothyroidism, and the age at which treatment was started are reviewed. The incidence of primary hypothyroidism was 1 in 3488 live births. Most of these cases were detected in a cord blood screening programme which was carried out between October 1973 and May 1980 in the Toronto region. Forty-eight infants with primary persistent hypothyroidism were classified by technetium scintiscanning as follows: 12 with athyrosis (non-visualised thyroid glands), 14 with ectopic thyroid glands, and 14 with goitrous thyroid glands. The remaining 8 infants comprised 4 with hypoplasia and 4 with transient hypothyroidism (2 idiopathic and 2 iodide induced). Although infants with athyrosis had a lower mean thyroxine value, their values overall were not significantly different from those of the other groups. Some infants, particularly those who were goitrous or ectopic, initially had normal thyroxine values. Skeletal maturation was more often delayed in athyrotic infants than in the ectopic or goitrous group. Radioactive iodine uptakes were appreciably higher in the goitrous group, and there was no significant difference between athyrotic and ectopic groups. The mean age at which treatment was started for all patients was 25 (range 6-120) days. The average age for starting treatment using initial thyroxine and secondary thyrotrophin testing in the initial stages of the cord blood screening was 36 days. The use of initial cord serum or dried blood thyrotrophin reduced the start of treatment to 14 days. It is concluded that: (1) It is important to determine the precise anatomical diagnosis, the biochemical severity, and the age at which treatment is started in order to assess the benefits of regional screening programmes in the detection of neonatal hypothyroidism. (2) Routine technetium scintiscanning before the start of treatment helps to determine the diagnosis. (3) Radioactive ¹³¹-I thyroid uptake studies are no longer routinely recommended; this is because of the radiation hazard and the lack of specificity in differentiating between the various anatomical types. (4) The feasibility of cord blood screening to detect the various causes of neonatal hypothyroidism is confirmed. (5) The time between final diagnosis and the institution of treatment can be reduced by 2 or 3 weeks if a thyrotrophin test is used initially from cord blood serum or, preferably, from dried blood spotted on filter paper; the latter is easier to post to a screening laboratory.