Context Accurate measurements of circulating hormones is essential for the practice of endocrinology. Immunometric assays employing the streptavidin-biotin system are widely used to measure hormones. However, these assays are susceptible to interference in patients taking biotin supplementations. This interference could mimic a coherent hormone profile, leading to misdiagnosis and unnecessary t...

The authors describe a case of a 37-year-old Malay lady with an unusually slow carbamazepine clearance, which may be related to genetic polymorphisms of drug metabolizing enzymes and transporters. When given a small daily dose of 200 mg immediate-release carbamazepine, this patient experienced drowsiness. Subsequently, she reduced her carbamazepine dose to 200 mg twice a week (on Mondays and Fr...

Mechanisms that have been proposed for peroxidase-catalyzed iodination require the utilization of 1 mol of H2O2 for organic binding of 1 mol of iodide. When we measured the stoichiometry of this reaction using thyroid peroxidase or lactoperoxidase at pH 7.0, we consistently obtained a ratio less than 1.0. This was shown to be attributable to catalase-like activity of these enzymes, resulting in...

Radioiodine, antithyroid drugs and surgery have been well established therapies for Graves' hyperthyroidism for several decades. However there remain large variations in practice among physicians in the preferred modality and the method of administration. Patient choice and perceptions also play a big role in the choice of treatment. Radioiodine may be given using fixed high doses or by calcula...

The relation between clinical and biochemical changes in thyrotoxicosis were studied in 12 patients with Graves's disease who were being treated with carbimazole. Clinical assessment (using the Crooks-Wayne index) was combined with the measurement of free thyroxine and triiodothyronine indices (FT4I and FT3I) and the assessment of two tissue markers of thyroid hormone action--sex-hormone-bindin...

Risks to mother, fetus and neonate from untreated Graves' hyperthyroidism during gestation are compelling reasons for recommending pre-conception counselling. Pre-conception counselling should include discussion as to the optimum treatment of Graves' hyperthyroidism in women wishing to become pregnant. Thyrotropin receptor antibodies remain elevated following radioiodine therapy, so medical or ...

OBJECTIVES To evaluate the efficacy of a fixed dose of radioactive iodine (131-I) in the treatment of thyrotoxicosis, and to identify risk factors associated with treatment failure. DESIGN Retrospective study. SETTING Thyroid Clinic of a regional hospital in Hong Kong. PATIENTS Patients receiving their first dose of radioactive iodine for the treatment of thyrotoxicosis during the inclusi...

BACKGROUND Thyrotoxicosis is common in the Australian community and is frequently encountered in general practice. Graves disease, toxic multinodular goitre, toxic adenoma and thyroiditis account for most presentations of thyrotoxicosis. OBJECTIVE This article outlines the clinical presentation and evaluation of a patient with thyrotoxicosis. Management of Graves disease, the most frequent ca...