Central thyroid disease

Secondary hypothyroidism (central thyroid disease) occurs as a result of pituitary or hypothalamic diseases that produce a deficiency in either TSH, TRH, or both. Isolated TSH defi-... 

In addition, other possible causes of dementia also need to be excluded, especially the treatable forms of cognitive impairment, such as that due to depression, chronic drug intoxication, chronic central nervous system infection, thyroid disease, vitamin deficiencies (i.e.. Bn and thiamine), central nervous system angitis, and normal-pressure hydrocephalus (Bird, 2008). Individuals who do not meet these criteria but have short-term memory loss and have only minimal impairment in other cognitive abilities and are not functionally impaired at work or at home are considered to have mild cognitive impairment (Petersen et al., 2001). 

Another problem facing the diagnosis of depression or mania is the fact that other medical conditions can cause similar symptoms. Among them are illnesses such as thyroid diseases, infectious diseases (the flu), cancers of the central nervous system, neurological disorders (multiple sclerosis), blood diseases, and even some reactions to metal toxicity. 

Isoprenaline is better avoided whenever stimulation of the heart or the central nervous system is undesirable, for example in patients with angina pectoris or thyroid disease. There is no reliable information on the risks in liver or renal disease. 

Thyroid carcinoma is the most common endocrine malignancy in the US, with 33550 new cases and 1530 deaths estimated for 2007. For unclear reasons, the annual incidence of thyroid carcinoma has risen over the last two decades (Jemal et ai, 2007). The discovery and use of radioactive iodine are major reasons that nuclear medicine originally achieved its specialty standing and central role in the management of thyroid disease. 

TSH test. Measuring the serum TSH has become the screen test of choice for thyroid disease. Primary hypothyroidism produces elevated TSH levels, whereas patients with primary hyperthyroidism (i.e., Graves disease) should have undetectable TSH values. This relationship is true only in individuals with an intact hypothalamic-pituitary-thyroid axis. Patients who present with a normal or detectable TSH level and elevated thyroid hormone concentrations require further evaluation to exclude central causes of hyperthyroidism. 

Adrenal insufficiency can be associated with hypothyroidism (either by autoimmune destruction or due to hypophyseal disease) and carries the risk of acute Addisonian crisis if thyroid substitution precedes glucocorticoid therapy. The diagnostic problem presented by the fact that a few patients with central hypothyroidism have a moderately increased serum TSH should be kept in mind (62). 

Cancer is uncommon during the first two decades of life, but is nonetheless a substantial concern. In the United States, cancer is diagnosed in approximately 12 400 children and adolescents annually and is the most common cause of death from any kind of disease between 1 and 19 years of age. In the United States and other developed countries, lymphoid neoplasms (leukaemia, lymphoma) and cancers of the central nervous system are the most common paediatric malignancies. Other kinds of childhood tumours include embryonal tumours of the retina, sympathetic nervous system, kidney, and liver tumours of bone and soft connective tissues and certain gonadal neoplasms. Different kinds of cancer (e.g. carcinomas of liver or thyroid) may predominate in children in parts of the world where specific environmental risk factors are more prevalent. 

The incidence of optic neuropathy in thyroid eye disease is 5% to 10%. The class 6 patient usually has mild to moderate proptosis and relatively shallow orbits. Thyroid optic neuropathy may be evidenced by papilledema, papillitis, or retrobulbar neuritis and usually is characterized by a painless and gradual loss of visual acuity. Common visual field defects include central scotomas, arcuate or altitudinal defects, paracentral scotomas, or generalized depressions. Thus visual field and optic disc examinations are the best diagnostic tools for early optic neuropathy. Occasionally, vision loss can occur precipitously over 1 or 2 weeks. Other features of optic nerve dysfunction frequently associated with the decreased visual acuity are color vision disturbances, afferent pupillary defects in the less proptotic eye in patients with asymmetric involvement, and prolongation of the pupil cycle time. 

CalzaL, EemandezM,Giuhani A, D Intino S, Pirondi S, SivihaS, Paradisi M, Desordi N, Giardino L (2005) Thyroid hormone and remyelination in adult central nervous system A lesson from an inflammatory-demy-ehnating disease. Brain Res Brain Res Rev 48 339-346. 

Thyroid Hypofunction Hypothyroidism is the most common disorder of thyroid function. It can be divided into patients who have a failure of the thyroid gland to produce sufficient thyroid hormone (primary hypothyroidism) and patients in which pituitary or hypothalamic disease is associated with impaired TSH stimulation (central or secondary hypothyroidism). Worldwide, primary hypothyroidism is caused most often by iodine deficiency. In areas where iodine is sufficient, chronic autoimmune thyroiditis (Hashimoto s thyroiditis) accounts for most cases. Other causes include postpartum thyroiditis, surgical removal, or radioactive iodine ablation of the gland. Hypothyroidism present at birth (cretinism) is the most common preventable cause of mental retardation in the world. 

The frequency of secondary or central hypothyroidism in adult patients is clearly lower than that of primary thyroid failure (Table 106.1). This form of hypothyroidism arises from diseases that interfere with the synthesis and release of hypothalamic TRH or pituitary TSH (Rose, 2001 Asteria et ai, 2001). The most common causes are pituitary adenomas and their therapy by surgery or radiotherapy. Less frequent causes of central hypothyroidism are hypothalamic tumors (craniopharyngioma), infiltrative diseases, head trauma, lymphocytic hypophysitis, infections, infarction and metastases (Beck-Peccoz et ai, 1996 Rose, 2001). 

Tripodi PF, Ruggeri RM, Campenni A, Cucinotta M, Mirto A, Lo Gullo R, Baldari S, Trimarchi F, Cucinotta D, Russo GT. Central nervous system vasculitis after starting methimazole in a woman with Graves disease. Thyroid 2008 18(9) 1011-3. 

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