Thyroid removal

Leon Eisenberg, MD, e-mail correspondence, May 9, 2000. Source for the effect of thyroid removal and electroshock therapy on mental health. 

Two years ago when I was in the United States I had part of my thyroid removed because I had a tumor. After the surgery I was supposed to swallow a pain pill, but I couldn t do it. Not because it was painful for me to swallow. No, because I couldn t stand the smell of the tablet. I said, Please, no This smell kills me I d rather have the pain ... 

Animals ex thyroid Grave s disease (thyrotoxicosis, excess thyroid hormone) - highly excitable Sir Cecil Spring-Rice (World War 1 British Ambassador to USA 1913-4 January 1918) WW2 General George Marshall (thyroid removed 1936)... 

Hyperthyroidism may be treated in several ways. One of these is interference with the synthesis of the thyroid hormones, possibly by removal of iodine. Thiourea and cyclic thioureas have this effect and of such cyclic compounds, thiouracil (1030 R = H), its 6-alkyl derivatives (1030 R = Me or Pr) and thiobarbital (1031) are effective thyroid drugs. Today only propylthiouracil (1030 R = Pr) is widely used, probably because it has fewer side effects than the others (71MI21302). The thiouracils are made by the Principal Synthesis from a /3-oxo ester (1032 R = H, Me, Pr, etc.) and thiourea (45JA2197) their fine structures are experimentally based (64AF1004). 

Hyperthyroidism, that is, the overproduction of thyroid hormones, is usually treated by surgical removal of the thyroid gland. Before such a procedure is undertaken, the hyperthyroidism is usually first brought under control by treatment with so-called antithyroid agents. 

Antithyroid drugp or thyroid antagonists are used to treat hyperthyroidism. In addition to the antithyroid drugs, hyperthyroidism may be treated by the administration of strong iodine solutions, use of radioactive iodine (131I), or by surgical removal of some or almost all of the tiiyroid gland (subtotal thyroidectomy). 

Figure 25-8. Control of adipose tissue lipolysis. (TSH, thyroid-stimulating hormone FFA, free fatty acids.) Note the cascade sequence of reactions affording amplification at each step. The lipolytic stimulus is "switched off" by removal of the stimulating hormone the action of lipase phosphatase the inhibition of the lipase and adenylyl cyclase by high concentrations of FFA the inhibition of adenylyl cyclase by adenosine and the removal of cAMP by the action of phosphodiesterase. ACTFI,TSFI, and glucagon may not activate adenylyl cyclase in vivo, since the concentration of each hormone required in vitro is much higher than is found in the circulation. Positive ( ) and negative ( ) regulatory effects are represented by broken lines and substrate flow by solid lines.

A deiodinase removes 1 from the inactive mono-and diiodothyronine molecules in the thyroid. This mechanism provides a substantial amount of the 1 used in T3 and T4 biosynthesis. A peripheral deiodinase in target tissues such as pituitary, kidney, and fiver selectively removes T from tfie 5 position of T4 to make T3 (see Figure 42-2), wfiicfi is a mucfi more active molecule. In this sense, T4 can be thought of as a prohormone, though it does have some intrinsic activity. 

Surgical removal of the thyroid gland should be considered in patients with a large gland (>80 g), severe ophthalmopathy, or a lack of remission on antithyroid drug treatment. 

General supportive measures, including acetaminophen as an antipyretic (aspirin or other nonsteroidal antiinflammatory drugs may displace bound thyroid hormone), fluid and electrolyte replacement, sedatives, digoxin, antiarrhythmics, insulin, and antibiotics should be given as indicated. Plasmapheresis and peritoneal dialysis have been used to remove excess hormone in patients not responding to more conservative measures. 

In 1858 Schiff removed the thyroid gland from animals and found they could not survive. From his, and later, Horsley s, experiments and from the clinical observations it was concluded that the effects of removal or damage to the thyroid were due to a loss of its internal secretions. Confirmation of this came when patients with myxoedema were successfully treated by thyroid extracts or even by eating thyroid tissue. 

Various factors may be associated with variations in calcium needs differences in vitamin D supply, differences in absorption and excretion, differences in activity of the parathyroid glands, differences in steroid hormone production, differences in thyroid function, differences in phosphate supply and utilization. 10 These we will not discuss, although these considerations may make it possible, in individual cases, to circumvent extra needs for calcium by removing the basis for the augmented need. We are here concerned primarily with the fact that individual people, under prevalent conditions, require amounts of calcium which may vary from individual to individual by a factor of 5. 

Plasma membrane - reductive removal of iodine from thyroid hormones 144-146 ER membrane - reductive removal of iodine from thyroid hormones 147... 

The hormone triiodothyronine (T3) accelerates both total energy expenditure and protein degradation. The hormone secreted by the thyroid gland is thyroxine, which is converted to the active hormone T3 in a process that removes an iodine atom from the 5 position of the thyronine ring. If, however, an iodine atom is removed from the 3 position, the result is the formation of reverse-Ts... 

Figure 16.14 Effect of thyroidectomy on survival of rats during starvation. Thyroidectomy protects rats from starvation that is, the number or rats surviving prolonged starvation is much larger when the thyroid gland is removed (Goldberg et al. 1978).

The transport of amino acids at the BBB differs depending on their chemical class and the dual function of some amino acids as nutrients and neurotransmitters. Essential large neutral amino acids are shuttled into the brain by facilitated transport via the large neutral amino acid transporter (LAT) system [29] and display rapid equilibration between plasma and brain concentrations on a minute time scale. The LAT-system at the BBB shows a much lower Km for its substrates compared to the analogous L-system of peripheral tissues and its mRNA is highly expressed in brain endothelial cells (100-fold abundance compared to other tissues). Cationic amino acids are taken up into the brain by a different facilitative transporter, designated as the y system, which is present on the luminal and abluminal endothelial membrane. In contrast, active Na -dependent transporters for small neutral amino acids (A-system ASC-system) and cationic amino acids (B° system), appear to be confined to the abluminal surface and may be involved in removal of amino acids from brain extracellular fluid [30]. Carrier-mediated BBB transport includes monocarboxylic acids (pyruvate), amines (choline), nucleosides (adenosine), purine bases (adenine), panthotenate, thiamine, and thyroid hormones (T3), with a representative substrate given in parentheses [31]. 

TSH is approved for medical use as a diagnostic aid in the detection of thyroid cancer/thyroid remnants in post-thyroidectomy patients. Thyroid cancer is relatively rare, exhibiting the highest incidence in adults, particularly females. First-line treatment is surgical removal of all or most of the thyroid gland (thyroidectomy). This is followed by thyroid hormone suppression therapy, which entails administration of T3 or T4 at levels sufficient to maintain low seum TSH levels through the negative feedback mechanism mentioned earlier. TSH suppression is required... 

The thyroid hormones T4 and T3 contain 65% and 59% of iodine respectively as an essential component for biological activity of the molecule. Iodine from dietary sources or medication enters the body via gastrointestinal tract. The recommended daily adult intake is 150-300 pg. Iodine is rapidly absorbed and enters the extracellular fluid pool. Iodide is removed from the blood largely by the thyroid and kidneys. The higher the intake the lower the fractional iodine uptake by the thyroid. 

A second dietary trace element, selenium, is also essential for normal thyroid hormone metabohsm. Selenium in the form of selenocysteine is a required component for three enzymes that remove iodide from thyroid hormones. Deiodination is the major metabohc pathway by which T4 and T3 are cleared from the system. After secretion by the thyroid gland, T4 may be deiodinated to yield either T3 or the physiologically inactive reverse Tj (3,3, 5 -triiodothyronine, or rX3). T3 and rTj are further deiodinated to form less active metabolites. Selenium, like iodine, is deficient in many areas of the world. 

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