Although the enzyme immunoassay technique we used is the first generation, our study remains important (25, 26, 27). Indeed, our work on 52 patients using 92 HRT tests with levothyroxine and levothyroxine and triiodothyronine combination allowed us to evaluate optimal hormonal balance. The dose placing the TSH delta in a zone of known euthyroidism, (4 to 20 micro IU/ml (IRMA)) was found to be 111.84 + 31.33 microg/d; 72.75 + 7.5 microg/m /d; 1.84 + 0.53 microg/kg/d. However, even when delta TSH is less than 4 micro IU/ml (1.03 + 1.47 micro IU/ml) under levothyroxine or levothyroxine and triiodothyronine combination (1.06 + 1.13 micro IU/ml) without any significant difference between the delta TSH means of these two groups, we found no change in cholesterol or heart rate apart from a weak negative correlation (r: 0.105) between heart rate and delta TSH of less than 4 micro IU/ml when levothyroxine and triiodothyronine were combined.