What is Pregnenolone?
Pregnenolone is often referred to as the "parent" or "precursor" steroid hormone because it serves as the starting point for the synthesis of numerous steroid hormones, including progesterone, DHEA, cortisol, aldosterone, testosterone, and estradiol. It is produced primarily in the adrenal glands, gonads, and brain from cholesterol through the action of the enzyme CYP11A1.
Beyond its role in hormone production, pregnenolone also functions as a neurosteroid, influencing cognition, memory, mood, sleep, and stress resilience through its effects on neurotransmitter signaling. Because pregnenolone sits at the top of the steroidogenesis pathway, abnormal levels may reflect alterations in adrenal function, gonadal hormone production, or overall endocrine regulation.
Why Test for Pregnenolone?
Evaluating pregnenolone levels helps clinicians assess steroid hormone production and investigate disruptions in adrenal or gonadal function. Pregnenolone testing is commonly used to investigate:
• Chronic fatigue or low energy
• Poor stress resilience or adrenal dysfunction
• Cognitive decline or brain fog
• Mood changes, anxiety, or depression
• Low libido or sexual dysfunction
• Hormonal imbalances affecting cortisol or sex hormones
• Monitoring hormone replacement or supplementation
• Comprehensive endocrine evaluations
Clinical Significance of Pregnenolone Levels
- Low Pregnenolone Levels: Low pregnenolone levels are commonly considered below ~20–30 ng/dL, although reference ranges vary by laboratory and age. Reduced pregnenolone may be associated with aging, adrenal insufficiency, chronic illness, prolonged physiological stress, or impaired steroid hormone synthesis.
Clinically, low pregnenolone may be associated with fatigue, poor stress tolerance, reduced cognitive function, mood disturbances, low libido, and diminished production of downstream steroid hormones.
- High Pregnenolone Levels: Elevated pregnenolone levels are generally considered above ~150–200 ng/dL, depending on laboratory reference ranges. High levels may occur with pregnenolone supplementation, adrenal hyperactivity, congenital adrenal enzyme disorders, or altered steroid metabolism.
Elevated pregnenolone does not necessarily indicate increased production of downstream hormones, as conversion into cortisol, progesterone, DHEA, or sex hormones depends on multiple enzymatic pathways. Excessively high levels from supplementation may be associated with insomnia, irritability, anxiety, headaches, or hormonal imbalance in susceptible individuals.
Actionable Insights
Pregnenolone should be interpreted alongside DHEA-S, cortisol, progesterone, testosterone, estradiol, and adrenal markers to provide a more complete assessment of steroid hormone production. Although pregnenolone is the precursor to multiple steroid hormones, the concept of "pregnenolone steal" is not supported by current evidence. Instead, chronic stress appears to influence hormone production through changes in HPA axis signaling and enzyme regulation. When abnormalities are identified, clinicians should focus on underlying causes rather than supplementation alone. Monitoring trends over time is often more informative than a single measurement.
Serum vs. Saliva Testing: Serum pregnenolone is the preferred method for evaluating circulating pregnenolone. Salivary testing is less well validated and should not be compared directly with serum results, as each measures a different physiological compartment.
Optimal Ranges
Note: Reference ranges vary by laboratory. In functional medicine, some providers may consider a narrower interpretive window to help guide clinical context. These values are not standardized and should be interpreted in conjunction with the ordering provider’s judgment.
“SHBG serves as a valuable indirect marker of metabolic and endocrine health. With patients on hormone therapies or with discrepant symptoms, measuring SHBG alongside free testosterone calculations helps avoid misinterpreting bioavailability, supporting more precise, individualized management while considering broader factors like thyroid status and liver function. Free Androgen Index (FAI): FAI = 100 × (Total Testosterone [nmol/L] ÷ SHBG [nmol/L]) Men generally targeting 30–100+ and women <5–7 depending on lab/age. men generally targeting 30–100+ and women <5–7 depending on lab/age.”
Dr. Mitch Ghen - Director of Physician Consultations, Access Labs
Disclaimer: Content on the Access Labs blog is for informational purposes only and reflects the views of individual contributors, not necessarily those of Access Labs. We do not endorse specific treatments, products, or protocols. This content is not a substitute for professional medical advice. Always consult a qualified healthcare provider regarding any medical concerns.