An Asymmetric DHT-Weighted Androgen Load and Androgen:Estrogen Ratio

The testosterone-to-estradiol (T:E) ratio is widely used to summarise hormonal balance in men on testosterone therapy, but it ignores dihydrotestosterone (DHT), the more potent androgen-receptor ligand. This note describes the androgen load model used in the TRT Plus app, which folds DHT into a single testosterone-equivalent quantity before the ratio with estradiol is taken. The model is asymmetric about a calibrated DHT reference point. Below the reference, the DHT contribution is linear and subtractive, so suppressed DHT (for example during 5α-reductase inhibition) lowers the load below total testosterone. At or above the reference, the contribution is scaled by a combined receptor-potency factor and amplified by a power term representing local paracrine DHT action. The resulting androgen:estrogen (A:E) ratio is mapped to five gauge states — Estrogenic, E2 Leaning, Balanced, E2 Low and Androgenic — which also inform how estradiol is classified in the TRT Plus Overall Score. We give the formal definition, the rationale for each term, edge-case handling, implementation conventions and limitations. Calibrated parameter values and state boundaries are proprietary and withheld. The model has not been validated against clinical outcomes and is published as a methods description, not as clinical guidance.