Here is a cut and paste about thick skin and Thyroid using gels and creams. From this link.
http://www.definitivemind.com/forums/showthread.php?t=38&highlight=Gels+Thyroid
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Ideally, for hormone replacement therapy, the transdermally based hormone is transferred into the fat layer of the skin. From there, the hormone can be released gradually into the bloodstream, producing stable level.
Alcohol-based gels are more useful for hormone replacement since they allow the hormone to be absorbed into the skin fat and to be slowly released into the blood stream.
Oil-based transdermal gels or creams - such as the PLO gels - are good for rapidly introducing substances into the system. They aren't as useful for hormone replacement therapy because they cause the hormone to bypass the skin fat and allow the hormone to directly go into the blood stream. This causes a large peak and a rapid fall in blood levels.
Both alcohol-based and oil-based gels or creams will result in good absorption generally. They generally result in predictable blood levels of hormones and medications. If the blood level does not go up, then it is not being absorbed. Thus if a testosterone transdermal does not result in an appreciable increase in testosterone it is not well absorbed.
Some people will have difficult absorbing a transdermal preparation. For example, people with hypothyroidism, can develop mxedema. This is a thickening of the skin due to the accumulation of mucin - a glue that holds cells together. This prevents transdermal absorption. In my patients, if a person develops lower thyroid hormone levels from either transdermal testosterone or estradiol, testosterone and estradiol levels fall. When I address thyroid hormone, testosterone and estradiol will again be abssorbed and levels rise. Other reasons for non-absorption include possible ethnic differences or genetic differences in skin such as oilier skin, etc.
One other reason a hormone level does not go up is that the dose used is too low. For example, many patients are given one 5 gram packet of Androgel to use. This is too low for many men. Since there is negative feedback controlling testosterone production, at a certain dose, the dose is too low to make up for the loss of one's testicular testosterone production, when exogenous testosterone is added. Testosterone level actually will decrease when only 1 5-gram pack is used in many men. The percentage of men where testosterone will be low rather than high decreases when two 5-gram packs of Androgel are used. This would be the starting dose I would use. In these men, there is evidence of absorption - such as DHT (dihydrotestosterone) levels going up. But testosterone is either the same or LOWER. In these men, testosterone in Androgel IS absorbed. But the dose is too low.
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Romeo B. Mariano, MD, physician, psychiatrist
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