Lecture 5 Short Answer

The most likely diagnosis is primary hypothyroidism.

The disorder is primary hyperthyroidism.

Yes, in primary hyperthyroidism, the TSH level is typically low.

<p>Once the T4 levels return to normal, the TSH levels will likely increase.</p> Signup and view all the answers

<p>Increased Thyroid hormone synthesis. Positive in Graves (homogenous scan), multinodular goitre, toxic adenoma (heterogenous scan)</p> Signup and view all the answers

<p>Positive in Graves. Useful if above scan is not possible, contraindicated</p> Signup and view all the answers

<p>Hashimoto’s, Graves. Signifies susceptibility to autoimmune thyroid disease. Establishes risk of thyroid disease in response to certain medications (e.g. amiodarone, lithium)</p> Signup and view all the answers

<p>Used as a tumor marker to monitor for recurrence in cancer of the thyroid</p> Signup and view all the answers

<p>Some clinical features of hyperthyroidism include weight loss, increased appetite, tremors, heat intolerance, and palpitations. Clinical features of hypothyroidism include weight gain, fatigue, constipation, cold intolerance, and dry skin.</p> Signup and view all the answers

<p>Causes of hyperthyroidism include Graves' disease, toxic multinodular goiter, and thyroiditis. Causes of hypothyroidism include Hashimoto's thyroiditis, iodine deficiency, and certain medications.</p> Signup and view all the answers

<p>Highly sensitive assays for TSH are required because they can detect even small changes in TSH levels, allowing for earlier detection of thyroid dysfunction.</p> Signup and view all the answers

<p>Risks of subclinical hyperthyroidism include further progression to osteoporosis, atrial fibrillation, and thyrotoxicosis if exposed to iodine.</p> Signup and view all the answers

<p>Risks of subclinical hypothyroidism include further progression of general well-being, depressive illnesses, and possible effects on fetal brain development during pregnancy.</p> Signup and view all the answers

<p>Primary hyperthyroidism can be caused by conditions such as Graves' disease and toxic nodules.</p> Signup and view all the answers

<p>Primary hypothyroidism can be caused by conditions such as Hashimoto's disease and pituitary/hypothalamic dysfunction.</p> Signup and view all the answers

<p>Increased BMR, Tachycardia, Heat intolerance, Diarrhoea, Weight loss, Increased appetite, Moist, velvet skin, Anxiety, Diminished fertility &amp; menstrual irregularities, Muscle weakness –Myopathy –CK levels may be raised (not as common as in hypothyroidism), Thyroid storm</p> Signup and view all the answers

<p>Decreased BMR, Bradycardia, Cold intolerance, Constipation, Weight gain, Decreased appetite, Dry coarse skin, Lethargy, Diminished fertility &amp; menstrual irregularities, Galactorrhoea, Delayed growth, Hyperlipidaemia, Muscle weakness, CK levels often raised, Myxoedema, Coma</p> Signup and view all the answers

<p>Diseases of the thyroid gland</p> Signup and view all the answers

<p>Derangements in TRH/TSH secretion e.g. due to diseases of the hypothalamus/pituitary, A tumour elsewhere in the body (ectopic) may produce TSH (ectopic TSH secretion), TSH-like activity of high levels of hCG</p> Signup and view all the answers

<p>T4</p> Signup and view all the answers

<p>T3</p> Signup and view all the answers

<p>TRH +ve -ve TSH Hypothalamus Pituitary -ve fT4, fT3 TSH +ve Thyroid Thyroid</p> Signup and view all the answers

<p>Important to normal brain development; increases responsiveness to catecholamines. Hypothyroidism: mentation slow. Hyperthyroidism, rapid mentation , irritability, restlessness. Thyroid hormone deficiency is an important cause of cretinism; newborn screening programmes in most developed countries. World-wide incidence 1/4000 -1/10000 Stimulates lipolysis. Potentiates influence of GH. Promotes normal growth &amp; development. Influences expression of myosin heavy chain (MHC) in SM and CM. Relationship to effects in thyroid disease e.g. myopathy in thyroid excess, unclear. Deficiency: delays in both bone growth &amp; epiphyseal closure. Secretion of GH also decreased. Excess or deficiency may result in muscle weakness; prolonged excess may cause severe myopathy. Hypothyroidism may be associated with elevated CK; hyperthyroidism, less often so.</p> Signup and view all the answers

<p>Possible interferences in the Roche fT4 assay include high doses of biotin, streptavidin antibodies, anti-ruthenium antibodies, and blocking or negatively interfering heterophilic antibodies. These interferences can affect the accuracy of the assay and lead to incorrect results.</p> Signup and view all the answers

<p>Some drugs that can increase TBG levels include oestrogens, methadone, heroin, tranquilisers, clofibrate, and 5-fluorouracil.</p> Signup and view all the answers

<p>Some drugs that can decrease TBG levels include glucocorticoids, androgens, and anabolic steroids.</p> Signup and view all the answers

<p>The purpose of measuring total T4/T3 and binding protein levels in the Roche fT4 assay is to calculate a free thyroid index. This index takes into account the total hormone levels and the binding protein levels, providing a more accurate assessment of the biologically free hormone levels.</p> Signup and view all the answers