Stacking T4 AND T3

[Roshambo]

Only 50mcg T4? Isn't endogenous production 75mcg/d? In that case you're shutting down endogenous production and establishing a lower serum level.

The thyroid gland produces three hormones -- thyroxine (tetraiodothyronine, T4), triiodothyronine (T3), and calcitonin. Calcitonin is primarily employed in bone homeostasis. The overall effect of the thyroid hormones T3 and T4 include necessary actions that contribute to growth, development, control of body temperature, and energy levels through control of basal metabolic processes.

Biosynthesis -- Iodine is a vital component of the hormones. A minimum dietary intake of 75 mcg is required for the daily production of thyroid hormones. (The USRDA for iodine is 150 mcg.) Dietary iodide is taken up by the thyroid gland by specialised transport systems in a process called iodide trapping. Once in the gland, iodide is converted to iodine by thyroidal peroxidase enzymes (which may be inhibited by elevated levels of iodine, as described below). The iodine is then combined with residues of the amino acid tyrosine to form mono-iodotyrosine (MIT) and di-iodotyrosine (DIT). With the products becoming incorporated into thyroglobulin, the thyroid storage sites of thyroid hormones. This process is termed iodide organification. The MIT and DIT may then combine to form tri- and tetra-iodothyronine (MIT + DIT --> triiodothyronine & DIT + DIT --> tetraiodothyronine). This occurs in a ratio of approximately 5:1 (5 T4 : 1 T3).

Release and Pharmacokinetics -- Upon stimulation by TSH, the thyroid hormones are released by a combination of proteolysis of thyroglobulin, freeing the hormone, and exocytosis (released into the circulation). Circulating thyroid hormone is highly bound (>99%) to thyroid binding globulin. (RECALL that œstrogens will increase and androgens decrease circulating levels of TBG.) Circulating levels of T4 and T3 closely match the ratios of the production, with the ratio of 4:1 (T4:T3). The active biological half-life of these hormones are 7 days for T4 and 1 day for T3. Thyroid hormones are then taken up by cells throughout the body where they may exert their effect. Once in the cell T4 is metabolised to T3 or inactive metabolites (this conversion also occurs in the thyroid and plasma, but to a lesser extent) by the enzyme iodinase

[alextg]

I think you should better ask on the HGH thread cause you're on hgh as you say ... Gear should most probably know about this :-) But as far as i know , while on HGH , you use T4

[G-Force]

The thyroid gland produces three hormones -- thyroxine (tetraiodothyronine, T4), triiodothyronine (T3), and calcitonin. Calcitonin is primarily employed in bone homeostasis. The overall effect of the thyroid hormones T3 and T4 include necessary actions that contribute to growth, development, control of body temperature, and energy levels through control of basal metabolic processes.

Biosynthesis -- Iodine is a vital component of the hormones. A minimum dietary intake of 75 mcg is required for the daily production of thyroid hormones. (The USRDA for iodine is 150 mcg.) Dietary iodide is taken up by the thyroid gland by specialised transport systems in a process called iodide trapping. Once in the gland, iodide is converted to iodine by thyroidal peroxidase enzymes (which may be inhibited by elevated levels of iodine, as described below). The iodine is then combined with residues of the amino acid tyrosine to form mono-iodotyrosine (MIT) and di-iodotyrosine (DIT). With the products becoming incorporated into thyroglobulin, the thyroid storage sites of thyroid hormones. This process is termed iodide organification. The MIT and DIT may then combine to form tri- and tetra-iodothyronine (MIT + DIT --> triiodothyronine & DIT + DIT --> tetraiodothyronine). This occurs in a ratio of approximately 5:1 (5 T4 : 1 T3).

Release and Pharmacokinetics -- Upon stimulation by TSH, the thyroid hormones are released by a combination of proteolysis of thyroglobulin, freeing the hormone, and exocytosis (released into the circulation). Circulating thyroid hormone is highly bound (>99%) to thyroid binding globulin. (RECALL that œstrogens will increase and androgens decrease circulating levels of TBG.) Circulating levels of T4 and T3 closely match the ratios of the production, with the ratio of 4:1 (T4:T3). The active biological half-life of these hormones are 7 days for T4 and 1 day for T3. Thyroid hormones are then taken up by cells throughout the body where they may exert their effect. Once in the cell T4 is metabolised to T3 or inactive metabolites (this conversion also occurs in the thyroid and plasma, but to a lesser extent) by the enzyme iodinase

so 75mcg of ioding is needed for thyroid function

doesnt say anything about natural production of T4 being 75mcg

perhaps this is what Drake was getting confused with

75mcg of T4 seems a lot to be producing naturally

[Drake Hotel]

so 75mcg of ioding is needed for thyroid function

doesnt say anything about natural production of T4 being 75mcg

perhaps this is what Drake was getting confused with

75mcg of T4 seems a lot to be producing naturally

No.

there is good agreement that about 1/3 of T4 daily produced (~130 nmol) in normal humans is converted to T3, which corresponds to about 40 nmol and thus 80% of the estimated total daily T3 production of 50 nmol.

http://www.thyroidmanager.org/Chapter3/3c/3c-frame.htm

130nmol T4 = ~101mcg

50nmol T3 = ~32.5mcg