Thyroid weight estimation

Radioiodine therapy utilizing 1311 is the preferred treatment for most patients over 21 years of age. In patients without heart disease, the therapeutic dose may be given immediately in a range of 80-120 M3i/g of estimated thyroid weight corrected for uptake. In patients with underlying heart disease or severe thyrotoxicosis and in elderly patients, it is desirable to treat with antithyroid drugs (preferably methimazole) until the patient is euthyroid. The medication is then stopped for 5-7 days before... 

Mandart G., Erbsman F. 1975 Estimation of thyroid weight by scintigraphy. Int.J.Nucl.Biol. 2 185-188. 

Artefactual increases of as much as 50% in total thyroxine, estimated by a competitive protein-binding assay, and of as much as 30% in triiodothyronine resin uptake are probably due to rapid and continuing lipolytic hydrolysis of triglycerides after blood has been drawn (126). Thyroid function tests should therefore always be performed on blood samples taken before (or a sufficient time after) heparin treatment (127). An increase in serum-free thyroxine concentrations has also been reported after low molecular weight heparin, by up to 171% in specimens taken 2-6 hours after injection. When specimens were obtained 10 hours after injection, the effects were smaller, but with concentrations still up to 40% above normal the results can still cause errors of interpretation (128). 

JL is a 68-year-old male who is admitted to the hospital for atrial fibrillation. During his hospitalization he is converted to normal sinus rhythm by quinidine. His past medical history includes congestive heart failure. His thyroid function is normal. His weight is 84 kg (IBW = 73 kg) and his estimated creatinine clearance is 68 ml/min. What would be an appropriate oral loading and maintenance dose ... 

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