Thyrotoxicosis is also known as Hyperthyroidism
Causes of thyrotoxicosis
Toxic multinodular goitre - This commonly occurs in older women. Again, antithyroid drugs are rarely successful in inducing a remission - although they can control the hyperthyroidism.
de Quervain's thyroiditis - This is transient hyperthyroidism from an acute inflammatory process, probably viral in origin. Apart from the toxicosis, there is usually fever, malaise and pain in the neck with tachycardia and local thyroid tenderness. Thyroid function tests show initial hyperthyroidism, the erythrocyte sedimentation rate (ESR) and plasma viscosity are raised, and thyroid uptake scans show suppression of uptake in the acute phase, though hypothyroidism , usually transient, may then follow after a few weeks. Treatment of the acute phase is with aspirin, using short-term prednisolone in severely symptomatic cases.
Toxic solitary adenoma/nodule (Plummer's disease)
Hyperthyroidism
Investigation of Thyrotoxicosis
Serum TSH is suppressed in hyperthyroidism (< 0.05 mU/L), except for the very rare instances of TSH hypersecretion. Diagnosis is confirmed with a raised serum T 4 , free T 4 or T 3 ; T 4 is almost always raised but T 3 is more sensitive as there are occasional cases of isolated 'T 3 toxicosis'. TPO and thyroglobulin antibodies are present in most cases of Graves' disease.
TSH receptor antibodies are not measured routinely, but are commonly present: thyroid stimulating immunoglobin (TSI) 80% positive, TSH-binding inhibitory immunoglobin (TBII) 60-90% in Graves' disease.
Long-term consequences of hyperthyroidism or Thyrotoxicosis
Long-term follow-up studies of hyperthyroidism show a slight increase in overall mortality, which affects all age groups, is not fully explained and tends to occur in the first year after diagnosis. Thereafter, the only long-term risk of adequately treated hyperthyroidism appears to be an increased risk of osteoporosis.
Treatment of Thyrotoxicosis
Treatment is with antithyroid drugs such as propylthiouracil or carbimazole, with beta- blockers reserved for presurgical treatment and immediate control of severe thyrotoxic symptoms.
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