Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| hCG (Human Chorionic Gonadotropin) | Thyroid (Levothyroxine / Liothyronine T3/T4) | |
|---|---|---|
| Category | Hormones | Hormones |
| Standard Dose | Research indicates 250-500 IU administered subcutaneously 2-3 times per week as a TRT adjunct for fertility and testicular maintenance. | Research indicates Levothyroxine (T4): 25-200 mcg daily based on TSH and free T4 levels. Liothyronine (T3): 5-25 mcg daily, often split into 2-3 doses. Combination T4/T3 ratio typically 4:1 to 3:1 when using both. |
| Timing | Administer on non-testosterone injection days if using twice-weekly TRT split. Consistent schedule (e.g., Tuesday/Saturday). Refrigerate reconstituted solution; use within 30-60 days. | Levothyroxine: Take on empty stomach, 30-60 minutes before breakfast or at bedtime (3+ hours after last meal). Separate from calcium, iron, and antacids by 4 hours. Liothyronine: Split into 2-3 daily doses due to short half-life (2.5 hours for T3 vs. 6-7 days for T4). |
| Cycle Duration | Ongoing for as long as TRT continues and fertility preservation is desired. Can be used in 4-8 week pre-PCT bursts to 'prime' testicular recovery. | Ongoing for diagnosed hypothyroidism. Optimization protocols may be shorter-term (3-6 months) with reassessment. |
| Evidence Level | strong_human | strong_human |
hCG mimics luteinizing hormone (LH) by binding the LH/CG receptor on testicular Leydig cells, activating the cAMP-PKA signaling cascade that upregulates steroidogenic acute regulatory protein (StAR) and CYP11A1, driving cholesterol conversion to pregnenolone and downstream testosterone synthesis. By maintaining intratesticular testosterone (ITT) levels during exogenous testosterone administration, hCG preserves Leydig cell function, spermatogenesis, testicular volume, and the production of neurosteroids (pregnenolone, DHEA) and estradiol within the testes.
Research indicates 250-500 IU administered subcutaneously 2-3 times per week as a TRT adjunct for fertility and testicular maintenance.
Administer on non-testosterone injection days if using twice-weekly TRT split. Consistent schedule (e.g., Tuesday/Saturday). Refrigerate reconstituted solution; use within 30-60 days.
Ongoing for as long as TRT continues and fertility preservation is desired. Can be used in 4-8 week pre-PCT bursts to 'prime' testicular recovery.
Levothyroxine (T4) is a prohormone converted to the active triiodothyronine (T3) by type 1 and type 2 deiodinase enzymes (DIO1/DIO2) in peripheral tissues. T3 binds nuclear thyroid hormone receptors (TRa and TRb), forming heterodimers with retinoid X receptors (RXR) that bind thyroid response elements (TREs) in DNA, directly modulating transcription of genes controlling basal metabolic rate, thermogenesis, mitochondrial biogenesis (via PGC-1a), cardiac output, and neuronal development. T3 also exerts rapid non-genomic effects on mitochondrial respiration, ion channels, and cell membrane transport.
Research indicates Levothyroxine (T4): 25-200 mcg daily based on TSH and free T4 levels. Liothyronine (T3): 5-25 mcg daily, often split into 2-3 doses. Combination T4/T3 ratio typically 4:1 to 3:1 when using both.
Levothyroxine: Take on empty stomach, 30-60 minutes before breakfast or at bedtime (3+ hours after last meal). Separate from calcium, iron, and antacids by 4 hours. Liothyronine: Split into 2-3 daily doses due to short half-life (2.5 hours for T3 vs. 6-7 days for T4).
Ongoing for diagnosed hypothyroidism. Optimization protocols may be shorter-term (3-6 months) with reassessment.
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