All of the following are features of Grave's disease except: September 2005
Ans. A: More common in males Graves disease, a syndrome of primary thyrotoxicosis, is caused by circulating thyroid receptor autoantibodies (TRab/ TSH-RAbs). The antibodies not only displace thyrotropin from the thyroid receptors but also mimic thyrotropin by activating the receptor to stimulate the synthesis and release T3 and T4. Because autoantibody production is not linked to the normal pituitary negative feedback loop, thyroid gland function becomes autonomous, and serum T4 and T3 levels become abnormally high and lead to clinical thyrotoxicosis. Because hormone synthesis is accelerated and thyroid gland radioiodine uptake is elevated, radionuclide scans demonstrate a diffuse increase in iodine uptake by the gland. Graves disease is closely associated with Hashimoto's disease (chronic lymphocytic thyroiditis) in which thyrotoxic/ cytotoxic antithyroid antibodies attack the gland. Thyrotoxicosis is eight times more common in females. Major clinical signs include weight loss (often accompanied by a increased appetite), anxiety, intolerance to heat, fatigue, hair loss, weakness, hyperactivity, irritability, apathy, depression, polyuria, polydipsia, and sweating. Additionally, patients may present with a variety of symptoms such as palpitations and arrhythmias (notably atrial fibrillation), shoness of breath (dyspnea), loss of libido, nausea, vomiting, and diarrhea. Long term untreated hypehyroidism can lead to osteoporosis Neurological manifestations can include tremor, chorea, myopathy, and in some susceptible individuals (paicularly of asian descent) periodic paralysis. The goiter in primary thyrotoxicosis is diffuse and vascular; it may be large or small, firm or soft, and a thrill and a bruit may be present. The onset is abrupt but remissions and exacerbations are not infrequent. Hypehyroidism is usually more severe than in secondary thyrotoxicosis but cardiac failure is rare. Manifestations of thyrotoxicosis not due to hypehyroidism per se, for example orbital proptosis, ophthalmoplegia and pretibial myxoedema, may occur in primary thyrotoxicosis. Thyroid dermopathy/ pretibial myxoedema is characterized by thickening of the skin, usually in areas of trauma, by deposition of hyaluronic acid in the dermis and subcutis.
More common in males
Tremor
Pretibial myxedema
Intolerance to heat