Our laboratory has been producing a range of bioidentical T3&T4 combination capsules since early 2000 for the treatment of hyopthyroidism. They can be made so they are equivalent in doses to thyroid extract for those people who prefer thyroid extract with the only difference being our capsules contain bioidentical thyroid hormones unlike thyroid extract which contain pig hormones. The T3 to T4 ratio of these compounded capsules are 1:4.2 just like thyroid extract which reflects the ratio of T3 to T4 found in pigs.
Our preference and recommendation is to use bioidentical T3&T4 combinations which are physiological to humans and thus contain bioidentical hormones in the physiological ratio of 1:3.3 T3 to T4 which reflects the ratio that occurs naturally in normal healthy humans. Healthy adults produce approximately 32mcg of T3 and between 80-100mcg of T4 each day in total.
The chart below lists equivalent doses of the various thyroid preparations supplied by our laboratory.
| Thyroid Extract USP (Porcine)T3/T4 ratio 1:4.2 | Compounded Bioidentical T3/T4 (porcine ratio 1:4.2) | Compounded Bioidentical Physiological T3/T4 (human ratio 1:3.3) | T4 (thyroxine) Equivalent | T3 (Tertroxin)Equivalent |
| 32.5mg – ½ Grain | T4 = 19mcgT3 = 4.5 | T4 = 16.8T3 = 5.1 | 37.2mcg | 9.3mcg |
| 65mg – 1 grain | T4 =38mcgT3= 9mcg | T4 = 33.3T3 = 10.1 | 73.7mcg | 18.4mcg |
| 97.5mg – 1½ grain | T4 = 57mcgT3 = 13.5mcg | T4 = 50.2T3 = 15.2 | 111mcg | 27.7mcg |
| 130mg – 2 grain | T4 = 76mcgT3 = 18mcg | T4 = 66.9T3 = 20.3 | 148mcg | 37mcg |
(This chart indicates theoretical equivalencies of various thyroid preparations based on the theoretical T4 strength being ¼ that of T3. Technically it is not entirely accurate to be used as a direct conversion between products for a number of reasons. Therefore the chart should only be used loosely for an initial conversion between products and then subsequent thyroid hormone tests used to adjust the doses in order to achieve optimal physiological levels)
The T3 and T4 used in our bioidentical T3/T4 combination products have been synthesized from the amino acid tyrosine and iodine so their molecular structure is exactly the same as human thyroid hormones. These are bioidentical so our bodies will be unable to differentiate the difference. The benefits of this is that human hormone equivalents are being used at the correct ratio and can also be highly purified (99.8% pure) thus eliminating the chance of contamination as is the case using porcine extract. In addition the dose of each hormone will be the same with every batch with less variation compared to thyroid extract where a 20% dose variation can occur and still be classed as USP pharmaceutical grade.
We recommend the best approach to treating thyroid deficiencies is to supplement both T3 and T4 at the appropriate doses in order to achieve optimal physiological levels of both hormones and thus ongoing monitoring is essential to achieve this.
Once initiated on either of these therapies you should have a blood test after 8 weeks to measure both T3 and T4 levels. These blood tests should be taken about eight to nine hours after taking your last dose. The dose of each individual hormone may then be individually fine tuned, if test results and symptoms indicate, to ensure they are both present at optimal physiological levels. Again symptoms should also be used as a guide to determine dosages as test results are not 100% accurate on their own.
NOTE: Patients whom have reverse T3 dominance should not use any T3/T4 combination weather it be thyroid extract or bioidentical combinations as the T4 in these products will only perpetuate the production of reverse T3 and keep the cycle going. These patients will require T3 only therapy.
Those patients on thyroxine may use a conversion table to find an appropriate T3/T4 starting dose and then adjust the dose of each hormone according to subsequent thyroid tests.
We were the first in Australia to provide these combinations as Dr Serafin always prefers to supplement hormones as close as possible to as mother nature had intended thus using bioidentical hormones at physiological doses and ratios made the most sense.
