Thyrotoxicosis factitia (alimentary thyrotoxicosis, exogenous thyrotoxicosis) refers to a condition of thyrotoxicosis caused by the ingestion of exogenous thyroid hormone. It can be the result of mistaken ingestion of excess drug, such as levothyroxine and triiodothyronine, or as a symptom of Munchausen syndrome. It is an uncommon form of hyperthyroidism. Patients present with hyperthyroidism and may be mistaken for Graves’ disease, if TSH receptor positive, or thyroiditis because of absent uptake on a thyroid radionuclide uptake scan due to suppression of thyroid function by exogenous thyroid hormones. Ingestion of thyroid hormone also suppresses thyroglobulin levels helping to differentiate thyrotoxicosis factitia from other causes of hyperthyroidism, in which serum thyroglobulin is elevated. Caution, however, should be exercised in interpreting thyroglobulin results without thyroglobulin antibodies, since thyroglobulin antibodies commonly interfere in thyroglobulin immunoassays causing false positive and negative results which may lead to clinical misdirection. In such cases, increased faecal thyroxine levels in thyrotoxicosis factitia may help differentiate it from other causes of hyperthyroidism. See also
Foodborne illness
Liothyronine

References


== External links ==
A major rate-limiting step in the pathway is at the level of the microsomal enzyme that catalyzes the conversion of HMG CoA to mevalonic acid, and that has been considered to be a prime target for pharmacologic intervention for several years.HMG CoA reductase occurs early in the biosynthetic pathway and is among the first committed steps to cholesterol formulation. Inhibition of this enzyme could lead to accumulation of HMG CoA, a water-soluble intermediate that is, then, capable of being readily metabolized to simpler molecules. This inhibition of reductase would lead to accumulation of lipophylic intermediates with a formal sterol ring. Lovastatin was the first specific inhibitor of HMG CoA reductase to receive approval for the treatment of hypercholesterolemia. The first breakthrough in efforts to find a potent, specific, competitive inhibitor of HMG CoA reductase occurred in 1976, when Endo et al. reported the discovery of mevastatin, a highly functionalized fungal metabolite, isolated from cultures of Penicillium citrium. Biosynthesis
The biosynthesis of lovastatin occurs via an iterative type I polyketide synthase (PKS) pathway. The six genes that encode enzymes that are essential for the biosynthesis of lovastatin are lovB, lovC, lovA, lovD, lovG, and lovF . The synthesis of dihydromonacolin L requires a total of 9-malonyl Coa . It proceeds in the PKS pathway until it reaches (E) a hexaketide, where it undergoes a Diels-Alder cycloaddition to form the fused rings. After cyclization it continues through the PKS pathway until it reaches (I) a nonaketide, which then undergoes release from LovB through the thioesterase encoded by LovG.