Clinical Analysis And Diagnostic Research Of Central Hypothyroidism

BackgroundCentral hypothyroidism (CH) is a rare subgroup of disease in hypothyroidism. The pathogenesis of central hypothyroidism is complex, including congenital genetic factors, pituitary disease (secondary hypothyroidism), hypothalamic lesions (tertiary hypothyroidism). In some cases, central hypothyroidism is an isolated defect of pituitary function, but in most cases it is combined with other pituitary hormone deficiencies(CPHDs).Resrarchers gradually realized that its clinical features, treatment and assessment were very different form primary hypothyroidism in the late 80s of last century. They found that pituitary mass lesions, especially pituitary adenomas, were the most common cause of central hypothyroidism[4]. In addition, surgery or radiation therapy for pituitary adenomas or other mass lesions could cause central hypothyroidism[5-7] . Other causes of acquired central hypothyroidism were infiltrative disorders affecting the pituitary or the hypothalamus (e.g. hemochromatosis, tuberculosis, syphilis, fungal infections), autoimmune lymphocytic hypophysitis, head trauma with injury of the stalk. The diagnosis of central hypothyroidism could only be made with the TSH and thyroid hormone determination at the same time.Wang discussed the diagnostic criteria for central hypothyroidism in China in 1997. However there were almost no treatise discussed the clinical features, treatment and assessment since then. Reseaches of hypothalamus-pituitary mass lesions(include complications of surgery and radiation therapy) were focused on electrolyte imbalance, infection, bleeding and hematoma, diabetes insipidus, and optic nerve damage, while rarely mentioned central hypothyroidism.Foreign scholars thought symptoms and signs of thyroid insufficiency in central hypothyroidism were usually the same but milder than those of primary hypothyroidism, but its Clinical features and gender differences were still not clear. And we also found that conditions of most patients with central hypothyroidism were severer in clinical practices. So it is important to make further understanding to central hypothyroidism, to find the clinical features of central hypothyroidism in our country which may be different form that of othe countries.Objectives(1) To analyze the clinical manifestation and laboratory data of 35 females with central hypothyroidism (CH) in our hospital, in order to find the features in females.(2) To analyze the clinical manifestations and laboratory data of all the 77 patients with CH, in order to make further understanding to the characteristics this disease and discuss the diagnostic criteria.MethodsRecorded variety of clinical symptoms, signs and laboratory data of all the patients, and dealt the data with SPSS17.0 statistical software. Results(1) About 40.0% of female cases were caused by Sheehan's syndrome,28.6% by hypothalamus-pituitary mass lesions, 25.7% by surgery and radiation therapy, and only 5.7% by ischemic encephalopathy and idiopathic CH.(2)About 45.5% of all the patients with CH were hypothalamus-pituitary mass lesions, 24.7% by surgery and radiation therapy, 22.1% by hypopituitarism and 7.7% by other diseases.(3) Most patients had not only the performance of hypothyroidism symptoms, but also the performances of primary disease or secondary gonadal, adrenal insufficiency symptoms.(4) The ratio in females whose FSH decreased was higher than that in males, while the ratios in females whose cortisol, testosterone, progesterone decreased were lower than that in males.(5)The cases whose thyroid functions were evaluated before and after surgery or radiation therapy in our hospital were only 11.6%. Conclusions(1) Sheehan's syndrome was the most common cause of CH in females, which was different from males. And some clinical manifestation were significantly different.(2) The most common cause was hypothalamus-pituitary mass lesions in all the patients, followed by surgery and radiation therapy, and then, hypopituitarism.(3) The rate of missed diagnosis of central hypothyroidism was rather high.(4) The diagnostic criteria were included the following conditions: radiotherapy doses of brain tumor were greater than 50Gy or the time of radiotherapy had past for more than 5 years; impairment of vision was found or MRI abnormalities were found in the optic nerve; biochemical abnormalities were found in gonadal, adrenal insufficiency; secondary anaemia did not achieve an improvement and the lack of erythroblastic was found in bone marrow biopsy.