There is the commercially available product in the United States called Armour Thyroid. It is a very popular medicine and has a large base of satisfied patients. In Australia the active ingredient from Armour (Thyroid Extract USP) can be compounded by Captain Stirling Pharmacy. It should be noted that thyroid is a schedule 4 medication and requires a medical practitioners prescription.
The dosage of Armour thyroid is measured in grains (1gr = 60mg) and is available in the following strengths; ¼ grain, ½ grain, 1 grain 1 ½ grain, 2 grain, 3, grain, 4 grain, 5 grain. This dosage refers to the amount of natural desiccated porcine thyroid extract it contains. The active ingredient will deliver both T3 and T4 the same as that in the human body. It also has traces of T2, T1 and calcitonin, which may be a reason why patients have found it works so well, but there is no evidence to suggest these are a factor.
Since the thyroid extract is porcine derived it tends to have more T3 proportionately than human thyroids (80/20 as compared to the human 93/7), and some patients will add a small amount of T4, but only after they find their optimal dose of the thyroid extract; the dose which removes all symptoms and gets the free T3 towards the upper part of the range. Many will do fine on the thyroid extract alone, though.
T4 being the storage hormone can be fine for once daily dosing but T3 is the active form and may only last a matter of hours in the body. Because of this the recommended dosage required should be taken twice daily. For some patients we actually compound a slow release form to deliver the T3 dose over a longer period of the day but a twice-daily dosage is still used.
The following chart outlines the comparative dosing between T3/T4 doses and thyroid extract dose. Since T3 is so much more potent than T4 a combined dose is not recommended and as such all thyroid extract doses should be measures in total dose of powder (eg ½ grain = 30mg etc). A grain weighs about 60mg of the thyroid powder, and traditionally has 9mcg of T3 and 38mcg of T4. T3 is the real workhorse and is far more potent than T4 (four times the potency). Therefore as an example; 60mg of thyroid powder would be roughly equivalent to T3 (4 x 9mcg = 36mcg) and T4 of 38 mcg gives a total equivalent T4 dose of 36+38 = 74mcg.