Pregnenolone Unit Converter
Pregnenolone Unit Converter
Convert serum pregnenolone between ng/dL, nmol/L, ng/mL and µg/L. This is the first steroid made from cholesterol, so it sits above every branch of the pathway — and it is the same molecule as the over-the-counter supplement, which is an entirely different conversation from the one on this page.
Pregnenolone converter
Mass ⇄ molarSerum pregnenolone 60 ng/dL in an adult woman
The conversion, derived from the molecular weight
ng/dL = nmol/L ÷ 0.031598
because 1 ng/dL is 10⁻⁸ g/L, and 10⁻⁸ ÷ 316.48 g/mol = 3.15976 × 10⁻¹¹ mol/L = 0.0315976 nmol/L
- MW 316.48
- pregnenolone, C₂₁H₃₂O₂ — the 21-carbon steroid produced when the cholesterol side chain is cleaved. Every other steroid hormone is downstream of it
- ng/dL → nmol/L is ÷ 31.6
- divide the ng/dL figure by about 32. 60 ng/dL is 1.90 nmol/L, 100 ng/dL is 3.16 nmol/L
- ng/mL = µg/L = ng/dL ÷ 100
- so 60 ng/dL is 0.60 ng/mL. A bare pregnenolone of “0.6” on a report is almost certainly ng/mL, and reading it as ng/dL understates it a hundredfold
- 0.03159757
- the factor Mayo Clinic Laboratories publishes on its own pregnenolone page, to eight figures. It agrees with the value derived here from the molecular weight, which is a useful independent check on the arithmetic
Worked example
Serum pregnenolone 60 ng/dL in an adult woman
60 × 0.031598 = 1.90 nmol/L (1.8959 before rounding)
60 ng/dL = 0.60 ng/mL = 0.60 µg/L
That is comfortably inside ARUP's adult female interval of 15–132 ng/dL (0.47–4.17 nmol/L)
It is also inside Mayo's adult interval — but only just, because Mayo's starts at 33 ng/dL and runs to 248 ng/dL (1.04–7.84 nmol/L). The same 20 ng/dL would be normal for ARUP and below range for Mayo
Two mass-spectrometry laboratories, two adult intervals
| Source | Method | Adult interval (ng/dL) | Same in nmol/L |
|---|---|---|---|
| ARUP 0092334 | HPLC-MS/MS | Female 18+: 15–132 | 0.47–4.17 |
| ARUP 0092334 | HPLC-MS/MS | Male 18+: 23–173 | 0.73–5.47 |
| Mayo PREGN | LC-MS/MS | 18 years and over: 33–248 (not sex-split) | 1.04–7.84 |
| ARUP 0092334 | HPLC-MS/MS | Tanner I: female 15–171, male 13–156 | 0.47–5.40 / 0.41–4.93 |
Where pregnenolone sits, and what an accumulation means
| Step | Enzyme | If this step is blocked |
|---|---|---|
| Cholesterol → pregnenolone | CYP11A1 (side-chain cleavage), with StAR delivering cholesterol | Almost nothing is made. Lipoid congenital adrenal hyperplasia — a global failure, not an isolated laboratory finding |
| Pregnenolone → 17-hydroxypregnenolone | CYP17A1 (17α-hydroxylase) | Pregnenolone and progesterone accumulate; cortisol and androgens fall; mineralocorticoid precursors rise and cause hypertension |
| Pregnenolone → progesterone | 3β-HSD type 2 | Pregnenolone, 17-hydroxypregnenolone and DHEA accumulate while their Δ4 counterparts fall. The Δ5-to-Δ4 ratio is the diagnostic finding |
| 17-hydroxyprogesterone → 11-deoxycortisol | CYP21A2 (21-hydroxylase) | The common congenital adrenal hyperplasia. 17-OHP accumulates; pregnenolone is too far upstream to be a useful marker of it |
The top of the pathway, and why that makes it an awkward test
Pregnenolone is what cholesterol becomes when the side-chain cleavage enzyme removes six carbons from it inside the mitochondrion. That single reaction is the committed step of steroidogenesis and the point at which ACTH exerts most of its acute control, through StAR, the protein that delivers cholesterol to the enzyme. Everything else — cortisol, aldosterone, the androgens, the oestrogens, progesterone — is downstream of the molecule this page converts. It is made in the adrenal cortex, the gonads, the placenta and, independently of all of them, in the brain.
Being at the top of a pathway is precisely what makes pregnenolone an awkward test. A hormone at the end of a chain tells you about one thing; a substrate at the beginning of a branching network tells you about whichever branch happens to be obstructed, and only if the obstruction is close enough for the backlog to reach it. In practice that means two enzyme defects. A 17α-hydroxylase (CYP17A1) block leaves pregnenolone and progesterone piling up while cortisol and every androgen fall away, with hypertension from the mineralocorticoid precursors that accumulate instead. A 3β-HSD type 2 defect leaves the whole Δ5 series — pregnenolone, 17-hydroxypregnenolone, DHEA — high relative to their Δ4 counterparts, and it is that ratio, not any single concentration, that makes the diagnosis. For 21-hydroxylase deficiency, which is the congenital adrenal hyperplasia almost everybody means when they use the phrase, pregnenolone is three steps too far upstream to be informative and 17-hydroxyprogesterone is the analyte to ask for.
This is also why the page is emphatic about which pregnenolone it is discussing. The serum steroid and the tablet sold as a nootropic or an anti-ageing supplement are the same molecule, and that is where the resemblance ends. The measurement on a report is a window onto an enzymatic pathway, interpreted against a reference interval and alongside four or five other steroids. Taking pregnenolone orally is an entirely separate question about what an exogenous substrate does when it enters a regulated network at the top, and neither the reference intervals on this page nor the conversion factor tells you anything useful about it. What is worth knowing at the bench is that recent supplement use will be visible in the result, so it belongs in the request details.
One last practical point. Serum concentrations of this steroid are low, the assays that measure it reliably are mass spectrometric, and the two major reference laboratories that publish intervals do not agree: ARUP gives adult women 15 to 132 ng/dL and men 23 to 173, while Mayo gives a single adult interval of 33 to 248 ng/dL. A result of 20 ng/dL is normal against one and low against the other. Convert the number here, then read it against the interval printed on the report it came from.
Frequently asked questions
How do I convert pregnenolone from ng/dL to nmol/L?
Multiply by 0.031598. A pregnenolone of 60 ng/dL is 1.90 nmol/L. Divide by 0.031598 to go back, or divide the ng/dL figure by roughly 32 as a mental check. The factor comes from the molecular weight, 316.48.
What is pregnenolone a test for?
Mainly for the two enzyme blocks immediately below it: 17α-hydroxylase deficiency, where pregnenolone accumulates with hypertension and absent androgens, and 3β-HSD type 2 deficiency, where the whole Δ5 series is raised relative to the Δ4 steroids. For 21-hydroxylase deficiency it is too far upstream to be useful — ask for 17-hydroxyprogesterone.
Is the pregnenolone supplement the same as the one measured in blood?
It is the same molecule, but that is where the resemblance ends. The serum measurement is read against a reference interval and alongside the rest of the steroid panel to locate an enzyme block. Taking it orally is a separate question entirely, and recent supplement use will show up in the result, so it should be stated on the request.
Why do two laboratories publish different pregnenolone reference intervals?
Both use mass spectrometry, but reference intervals depend on the population sampled, the extraction and the calibration. ARUP gives adult women 15–132 ng/dL and men 23–173 ng/dL; Mayo gives a single adult interval of 33–248 ng/dL. A value of 20 ng/dL is normal against one and low against the other, which is why the report’s own interval is the one to use.
Why do ng/mL and ng/dL differ by a hundred?
A decilitre is 100 mL, so a concentration per decilitre is a hundred times the same concentration per millilitre. 60 ng/dL is 0.60 ng/mL, and µg/L is numerically identical to ng/mL. A bare “0.6” on a pregnenolone report is almost certainly ng/mL.
Related calculators
References
- ARUP Laboratories. Test 0092334 — Pregnenolone by LC-MS/MS, Serum or Plasma. Quantitative high performance liquid chromatography-tandem mass spectrometry. Adults 18 years and older: female 15–132 ng/dL, male 23–173 ng/dL; Tanner stage I: female 15–171, male 13–156 ng/dL.
- Mayo Clinic Laboratories. Test ID: PREGN — Pregnenolone, Serum. Liquid chromatography tandem mass spectrometry. Reference values 18 years and older: 33–248 ng/dL. Conversion to nmol/L by multiplying by 0.03159757.
- Miller WL, Auchus RJ. The molecular biology, biochemistry, and physiology of human steroidogenesis and its disorders. Endocr Rev. 2011;32(1):81–151. doi:10.1210/er.2010-0013
- Speiser PW, Arlt W, Auchus RJ, et al. Congenital Adrenal Hyperplasia Due to Steroid 21-Hydroxylase Deficiency: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(11):4043–4088. doi:10.1210/jc.2018-01865
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