Pregnenolone And TRT: What This Hormone Does For You

Pregnenolone and TRT are connected through the steroid hormone pathway, but the clinical relationship between them isn't as clear-cut as many online sources suggest. Pregnenolone is the first hormone the body makes from cholesterol, and it serves as the precursor to steroid hormones like testosterone, DHEA, cortisol, and progesterone. When a man starts TRT for diagnosed hypogonadism, the suppression of endogenous hormone production may also reduce pregnenolone output, though large-scale studies on this specific interaction remain limited.

Marek Health provides telehealth evaluations for men with hormone concerns, including lab panels that can measure pregnenolone alongside testosterone and related steroid markers. This article covers what the current evidence says about pregnenolone and TRT, where the research gaps fall, and how providers approach monitoring when both are part of a treatment plan.

What Is Pregnenolone?

Pregnenolone is a C-21 steroid hormone synthesized from cholesterol in the mitochondria of adrenal, gonadal, and brain cells. The enzyme CYP11A1 (cholesterol side-chain cleavage) converts cholesterol to pregnenolone in what is the rate-limiting step of all steroid hormone production. Every downstream steroid, from cortisol to testosterone to estradiol, depends on this single conversion as its starting point.

Pregnenolone is sometimes referred to as the "parent steroid" in clinical shorthand because it sits at the top of two branching pathways. The delta-5 pathway converts pregnenolone to 17-alpha-hydroxypregnenolone, then to DHEA, then to testosterone. Providers sometimes test DHEA-S levels alongside pregnenolone to assess this branch. The delta-4 pathway converts pregnenolone to progesterone, then branches toward cortisol and aldosterone.

The proportions flowing through each branch shift with age, stress, nutritional status, and inflammation.

How Are Pregnenolone and TRT Connected?

TRT delivers exogenous testosterone, which signals the hypothalamic-pituitary-gonadal (HPG) axis to reduce its own output. This is the same feedback mechanism that suppresses luteinizing hormone (LH) and follicle-stimulating hormone (FSH) during treatment, which is why TRT can affect fertility in men and testicular volume.

The question for pregnenolone is whether this suppression extends upstream. When Leydig cell stimulation decreases because LH drops, those cells may produce less pregnenolone as a result, though no clinical trial has directly measured this change during TRT. Adrenal pregnenolone production, which runs through a separate axis (ACTH-driven), may remain intact, but the extent of any gonadal decline hasn't been quantified in controlled studies.

No large randomized controlled trial has measured pregnenolone changes specifically during TRT for hypogonadism. The Endocrine Society guideline does not address pregnenolone monitoring as a standard component of testosterone therapy (Bhasin et al., 2018). Providers who include pregnenolone in their lab panels are working from clinical observation and steroidogenesis theory rather than guideline-level evidence.

Men who notice shifts in mood or energy during TRT sometimes have pregnenolone levels checked to evaluate whether upstream steroid production has dropped alongside HPG axis suppression.

Pregnenolone as a Neurosteroid

Pregnenolone is one of the most abundant neurosteroids in the brain and serves as the precursor to all other brain-synthesized steroids. Preclinical research has shown that pregnenolone sulfate (PREGS) can modulate NMDA receptor activity and increase acetylcholine release in the hippocampus, both of which are involved in memory formation and learning (Marx et al., 2009).

A proof-of-concept trial in patients with schizophrenia found that within-group serum pregnenolone increases correlated with improvements on cognitive testing batteries, though overall group differences between pregnenolone and placebo did not reach statistical significance (Marx et al., 2009). Separate rodent research demonstrated that reduced hypothalamic pregnenolone was associated with impaired recognition memory in models of metabolic dysfunction (Ramirez et al., 2022).

These findings are early-stage. No trial has specifically examined cognitive outcomes when pregnenolone is added to a TRT regimen in men with diagnosed deficiency. The neurosteroid research suggests a plausible mechanism, but clinical recommendations for men on TRT can't be drawn from it yet.

Does Pregnenolone Supplementation Raise Testosterone?

No large clinical trial has shown that oral pregnenolone supplementation produces a consistent, clinically meaningful increase in serum testosterone. Pregnenolone is a precursor in the steroid pathway, but supplementing it does not guarantee downstream conversion. The body distributes pregnenolone across multiple pathways (cortisol, progesterone, DHEA, testosterone), and the destination depends on enzyme activity that varies by individual.

Small observational studies have noted associations between lower pregnenolone and lower total and free testosterone in certain populations, including shift workers and men with obesity. These associations don't establish that pregnenolone supplementation corrects the deficit.

Neither the Endocrine Society nor the AUA includes pregnenolone as a recommended adjunct in their testosterone therapy guidelines (Bhasin et al., 2018; Mulhall et al., 2018). Providers who prescribe pregnenolone alongside TRT do so on an individualized basis, typically after measuring baseline levels and monitoring response over time.

Factors That May Support Pregnenolone Production

Cholesterol is the raw material for pregnenolone synthesis, so adequate dietary fat intake matters. Diets that severely restrict fat or cholesterol can theoretically limit substrate availability for steroidogenesis, though this has not been studied in controlled clinical settings specific to pregnenolone.

Several nutrients play supporting roles in steroid hormone production. Zinc-rich foods provide a cofactor for enzymes in the testosterone synthesis pathway. Magnesium status supports adrenal function, and vitamin D status has been associated with testosterone levels in observational research, though the clinical significance of supplementation for hormone production isn't settled.

Sleep is also a factor. Steroid hormone production follows circadian patterns, and shortened or disrupted sleep has been associated with lower testosterone in multiple studies. Some clinicians hypothesize that chronic stress may redirect pregnenolone toward cortisol production at the expense of sex hormone pathways, a concept sometimes called "pregnenolone steal." This term is more common in clinical discussion than in peer-reviewed literature, and no controlled trial has confirmed the mechanism in humans.

Monitoring Pregnenolone on TRT

Pregnenolone is not part of the standard monitoring protocol for TRT. The Endocrine Society guideline recommends baseline and follow-up blood work, with specific markers selected based on clinical indication and individual risk (Bhasin et al., 2018). The AUA recommends routine safety blood work during TRT to monitor for known risks (Mulhall et al., 2018).

Providers who add pregnenolone testing typically include it alongside other steroid pathway markers, with the specific panel tailored to the patient. This approach reflects a more detailed assessment of the steroidogenesis pathway rather than the standard guideline-recommended panel.

The February 2025 FDA labeling update added a blood pressure warning to all testosterone products following the TRAVERSE trial, while removing the prior cardiovascular boxed warning (Lincoff et al., 2023). That trial showed a noninferiority result for major cardiac events but higher rates of atrial fibrillation, pulmonary embolism, and acute kidney injury in the testosterone group. These findings apply to all TRT patients, including those who add pregnenolone to their protocol.

Pregnenolone and TRT intersect at the biochemical level, but clinical evidence supporting pregnenolone as a standard adjunct to testosterone therapy remains limited. Men considering hormone evaluation should discuss pregnenolone testing with their provider if upstream steroid pathway assessment is a priority. Individual results vary, and treatment decisions should follow lab confirmation and clinical evaluation.

Disclaimer: This blog post is intended for informational purposes only and should not be considered medical advice. Always consult a healthcare professional before making changes to your health routine.

FAQs

What is the connection between pregnenolone and TRT?

Pregnenolone is the first steroid hormone the body synthesizes from cholesterol, and it sits at the top of the pathway that produces testosterone. TRT suppresses the HPG axis, which reduces Leydig cell activity and may lower gonadal pregnenolone production. Adrenal pregnenolone production operates through a separate ACTH-driven axis and may remain less affected.

Does pregnenolone supplementation increase testosterone levels?

No large RCT shows that pregnenolone supplementation consistently raises serum testosterone. Pregnenolone is a precursor, but the body distributes it across multiple hormone pathways. Neither the Endocrine Society nor the AUA recommends pregnenolone as an adjunct to TRT.

Should pregnenolone be tested before starting TRT?

It is not part of the standard diagnostic workup for hypogonadism. The AUA defines the diagnostic threshold as consistently low total testosterone on repeated early-morning blood draws, confirmed alongside clinical symptoms. Some providers add pregnenolone and DHEA-S to the panel for a broader view of steroidogenesis, but this is clinician-driven rather than guideline-mandated.

Can TRT lower pregnenolone levels?

TRT suppresses LH, which reduces Leydig cell stimulation and may decrease gonadal pregnenolone production. No large trial has quantified this effect specifically. Adrenal pregnenolone production, which is independent of LH, may continue at its baseline rate.

Is pregnenolone a neurosteroid?

Pregnenolone and its sulfated form (PREGS) are among the most abundant neurosteroids in the brain. Animal research has shown associations between brain pregnenolone levels and memory, and a proof-of-concept trial in schizophrenia patients found within-group correlations between serum pregnenolone increases and cognitive test scores, though overall group differences were not statistically significant. Clinical recommendations for TRT patients can't be drawn from these early findings.

What did the TRAVERSE trial find about testosterone and heart risk?

The TRAVERSE trial was a large, multicenter, placebo-controlled study in men with hypogonadism and preexisting or high risk of cardiovascular disease. The primary cardiovascular endpoint met the noninferiority threshold, meaning TRT did not increase the rate of major cardiac events compared to placebo. Higher rates of atrial fibrillation, pulmonary embolism, and acute kidney injury occurred in the testosterone arm. The FDA responded with class-wide labeling changes in February 2025.

References

• Cell Metab. 2022;34(2):269-284.

• FDA Drug Safety Communication: Class-wide labeling changes for testosterone products. February 28, 2025.

• J Clin Endocrinol Metab. 2018;103(5):1715-1744.

• J Urol. 2018;200(2):423-432.

• N Engl J Med. 2023;389:107-117.

• Neuropsychopharmacology. 2009;34(8):1885-1903.