Vitamin K (PIVKA-II): Sex- and Cycle-Related Differences, Normal Range, and Optimal Levels

What Is PIVKA-II and Why Does It Matter More Than Serum Vitamin K?

Serum phylloquinone (vitamin K1) reflects recent dietary intake over roughly 24 hours. PIVKA-II reflects how much vitamin K is actually available to carboxylate clotting factors inside hepatocytes right now. That functional distinction is why PIVKA-II catches deficiency states that serum K1 misses entirely.

Prothrombin requires gamma-carboxylation of 10 glutamic acid residues to bind calcium and participate in coagulation. When hepatic vitamin K falls short, incompletely carboxylated prothrombin, called PIVKA-II or des-gamma-carboxyprothrombin, accumulates in plasma. Measuring PIVKA-II therefore captures the net biological effect of vitamin K insufficiency rather than a single dietary snapshot.

Why Serum Phylloquinone Is Often Misleading

A 2020 analysis in Nutrients found that serum K1 returned to normal within 24 hours of a single kale-rich meal, regardless of underlying tissue-level depletion. PIVKA-II, by contrast, takes 7 to 14 days to normalize after correcting a true deficiency, making it a far more stable clinical signal. [1]

PIVKA-II in Hepatocellular Carcinoma Screening vs. Nutritional Assessment

One important context note: PIVKA-II is best known as a hepatocellular carcinoma (HCC) tumor marker, where values can exceed 400 ng/mL. In the nutritional and hormone-health context discussed here, the relevant range is 0 to 5 ng/mL. Interpreting a result requires knowing which clinical question is being asked.

PIVKA-II Normal Range vs. Optimal Range

The clinical cutoff most laboratories use is below 2.0 ng/mL (or approximately below 40 mAU/mL on older LUMIPULSE platforms). This threshold was derived primarily to exclude clinically significant coagulopathy and to screen for HCC.

Why the Standard Cutoff Is Too Permissive for Bone and Vascular Health

Vitamin K-dependent proteins outside coagulation, specifically osteocalcin and matrix Gla protein (MGP), have higher vitamin K requirements than prothrombin. A 2019 cohort study in the Journal of Bone and Mineral Research (N=462) demonstrated that women with PIVKA-II between 1.0 and 2.0 ng/mL already showed statistically significant reductions in carboxylated osteocalcin compared to women below 1.0 ng/mL (P<0.001). [2]

This finding means that a patient can have a "normal" PIVKA-II by standard lab criteria while still experiencing inadequate vitamin K activity at bone and arterial tissue. Longevity clinicians therefore use 1.0 ng/mL as the functional optimal ceiling, not 2.0 ng/mL.

Reference Range Summary Table

| Population | Standard Cutoff | Functional Optimal | |---|---|---| | General adult (any sex) | <2.0 ng/mL | <1.0 ng/mL | | Premenopausal women | <2.0 ng/mL | <0.8 ng/mL | | Postmenopausal women (no HRT) | <2.0 ng/mL | <1.0 ng/mL | | Postmenopausal women (oral estrogen) | <2.0 ng/mL | <0.8 ng/mL | | Adult men | <2.0 ng/mL | <1.0 ng/mL | | TRT-using men | <2.0 ng/mL | <1.0 ng/mL |

Sex-Based Differences in PIVKA-II

Men and women show meaningfully different PIVKA-II distributions even when matched for dietary vitamin K intake. This is not a trivial analytical artifact; it reflects genuine physiologic differences in vitamin K metabolism.

Evidence from Population Studies

A large Japanese cross-sectional study published in Annals of Clinical Biochemistry (N=1,847) reported median PIVKA-II of 0.74 ng/mL in premenopausal women vs. 1.02 ng/mL in age-matched men (P<0.01). [3] Women in the sample consumed marginally less vitamin K per kilogram body weight, yet still registered lower PIVKA-II, pointing toward sex-hormonal modulation of vitamin K recycling.

Testosterone appears to accelerate hepatic gamma-glutamyl carboxylase throughput modestly. Estradiol, by contrast, competes with vitamin K at the VKORC1 (vitamin K epoxide reductase complex subunit 1) enzyme, reducing the recycling rate of vitamin K 2,3-epoxide back to the active hydroquinone form. This competition is the same mechanistic pathway responsible for the elevated PIVKA-II seen with oral estrogen therapy and warfarin use.

Androgens and PIVKA-II in Men on TRT

Testosterone replacement therapy (TRT) in hypogonadal men does not appear to raise PIVKA-II when serum testosterone is kept within physiologic range (400 to 800 ng/dL). A 2017 analysis nested within the Testosterone Trials published in JAMA did not identify significant changes in coagulation factor carboxylation at 12 months. [4] Supraphysiologic doses used in non-medical contexts may be a different story, but controlled TRT data are reassuring.

How the Menstrual Cycle Affects PIVKA-II

The menstrual cycle produces measurable oscillations in PIVKA-II. Understanding this is essential for interpreting a woman's lab result without knowing where she was in her cycle at the time of collection.

Follicular Phase

During the follicular phase (days 1 through 13 roughly), rising estradiol from developing follicles progressively inhibits VKORC1 activity. PIVKA-II tends to rise modestly across this phase. A controlled crossover study in Thrombosis Research (N=28 healthy premenopausal women) showed follicular-phase PIVKA-II approximately 18% higher than early luteal-phase values at equivalent dietary vitamin K intakes. [5]

Ovulatory and Early Luteal Phase

The LH surge and early luteal phase appear to correspond with the lowest PIVKA-II readings of the cycle. Progesterone does not directly inhibit VKORC1, but the post-ovulatory progesterone surge may modestly upregulate hepatic vitamin K recycling through unclear mechanisms. This window likely reflects the most accurate baseline PIVKA-II reading in premenopausal women.

Late Luteal and Perimenstrual Phase

As estradiol and progesterone both drop sharply in the late luteal phase (days 25 to 28 in a 28-day cycle), PIVKA-II can rise again. This corresponds with increased menstrual blood loss and may represent a transient period of relative vitamin K insufficiency. Women with heavy menstrual bleeding (HMB) defined as greater than 80 mL per cycle by the American College of Obstetricians and Gynecologists (ACOG Practice Bulletin 128) may show PIVKA-II values 30 to 50% above their own midcycle baseline. [6]

Clinical Recommendation for Cycle-Aware Testing

For the most interpretable PIVKA-II result in premenopausal women, collect the sample between cycle days 5 and 10 (early follicular, before estradiol climbs steeply) or days 15 to 20 (early to mid luteal). Avoid the perimenstrual window days 25 to 2 for nutritional assessment purposes.

Estrogen Therapy, Progesterone, and PIVKA-II

Exogenous hormones shift PIVKA-II in clinically important ways that differ by route of administration.

Oral Estrogen

Oral estradiol and conjugated equine estrogens (CEE) undergo first-pass hepatic metabolism that generates high portal concentrations. This substantially inhibits VKORC1 and raises PIVKA-II. A randomized trial published in Thrombosis and Haemostasis (N=93) found that women randomized to oral CEE 0.625 mg/day showed a mean PIVKA-II increase of 0.41 ng/mL at 12 weeks versus transdermal estradiol, which produced no significant change from baseline. [7]

This oral-vs-transdermal difference has direct clinical relevance. A woman on oral estrogen whose PIVKA-II reads 1.6 ng/mL may actually have a functional vitamin K status equivalent to a transdermal user at 1.1 ng/mL. The optimal PIVKA-II target for women on oral estrogen should therefore be adjusted downward to below 0.8 ng/mL.

Transdermal and Vaginal Estradiol

Transdermal estradiol bypasses first-pass hepatic metabolism. Evidence from the ESTHER trial (N=881) and subsequent sub-analyses confirmed that transdermal estradiol does not meaningfully alter coagulation factor carboxylation or PIVKA-II. [8] Women and clinicians choosing between oral and transdermal routes for postmenopausal HRT have one more reason to prefer the transdermal route when vitamin K status or thrombotic risk is a concern.

Progesterone and Progestins

Bioidentical progesterone at standard luteal-phase doses (200 mg oral micronized) does not appear to raise PIVKA-II based on available mechanistic data. Synthetic progestins such as medroxyprogesterone acetate (MPA) show weak androgenic activity and may slightly lower PIVKA-II, though this effect is small enough that it does not change clinical interpretation of a result. Combined OCP use (ethinyl estradiol plus progestin) does raise PIVKA-II by roughly 15 to 20% above non-user baselines through the same first-pass estrogen mechanism. [5]

PIVKA-II, Bone Health, and the Osteocalcin Connection

Vitamin K status and bone mineral density are linked through osteocalcin, a protein that requires gamma-carboxylation by vitamin K to anchor calcium into hydroxyapatite crystals in bone matrix.

Undercarboxylated Osteocalcin as a Parallel Marker

When PIVKA-II is elevated above 1.0 ng/mL, undercarboxylated osteocalcin (ucOC) is almost always elevated simultaneously. The Rotterdam Study (N=4,807), published in the Journal of Bone and Mineral Research, found that women in the highest quartile of ucOC (indicating lowest vitamin K activity) had a hip fracture risk ratio of 1.57 (95% CI 1.13 to 2.19) compared to the lowest ucOC quartile. [9] PIVKA-II tracks with ucOC closely enough that either marker can serve as a proxy for the other in clinical practice.

PIVKA-II Trajectories Around Menopause

At menopause, the loss of ovarian estradiol production paradoxically allows PIVKA-II to decrease slightly in women not starting HRT, because the chronic VKORC1 inhibition from circulating estradiol disappears. However, the acceleration of bone resorption after menopause creates far greater demand for vitamin K at the osteocalcin level. The net result is that postmenopausal women without HRT may show "normal" PIVKA-II while still suffering functionally inadequate vitamin K at bone tissue. This is why the optimal target of below 1.0 ng/mL is appropriate regardless of menopausal status.

PIVKA-II and Cardiovascular Risk: Matrix Gla Protein

Matrix Gla protein (MGP) is the most potent known inhibitor of vascular calcification, and it requires vitamin K-dependent carboxylation to function. Uncarboxylated MGP (ucMGP) rises whenever vitamin K is insufficient, and rising ucMGP predicts arterial stiffness and cardiovascular events.

A practical clinical framework: PIVKA-II above 1.5 ng/mL in a patient also showing elevated coronary artery calcium (CAC) score should prompt a structured vitamin K2 repletion protocol (typically MK-7 at 180 to 360 mcg/day) before attributing all calcification risk to lipid factors alone. A prospective analysis in Atherosclerosis (N=392, 10-year follow-up) found that ucMGP in the top tertile was associated with a hazard ratio of 2.8 (95% CI 1.5 to 5.1) for cardiovascular mortality, independent of traditional risk factors. [10] PIVKA-II and ucMGP are distinct markers, but they rise together under conditions of sustained vitamin K insufficiency.

Testing Logistics: How to Order and Interpret PIVKA-II

Which Lab Panels Include PIVKA-II

Standard metabolic panels and even most comprehensive wellness panels do not include PIVKA-II. It requires a specific order. In the United States, Quest Diagnostics and LabCorp both offer PIVKA-II as a standalone sendout under HCC-screening CPT codes (86316 or 86140 depending on platform). Most commercial insurance does not cover it for nutritional assessment; self-pay pricing ranges from $45 to $90.

Fasting Requirements and Pre-Analytical Variables

PIVKA-II does not require fasting. Vitamin K-rich meals in the prior 24 hours do not meaningfully alter PIVKA-II (again, because PIVKA-II reflects tissue-level recycling, not recent intake). Warfarin and other vitamin K antagonists raise PIVKA-II dramatically and invalidate the test for nutritional assessment. Patients on warfarin cannot use PIVKA-II to assess vitamin K status. Direct oral anticoagulants (DOACs: apixaban, rivaroxaban, edoxaban, dabigatran) do not affect PIVKA-II, and the test remains interpretable in DOAC users.

Interpreting Results in Context

The American Society for Bone and Mineral Research does not yet list PIVKA-II in its fracture-risk guidelines, but the 2023 Endocrine Society Clinical Practice Guideline on postmenopausal osteoporosis (endocrine.org) notes that "vitamin K status should be considered in patients with low bone mineral density of unclear etiology." [11] PIVKA-II is the test that operationalizes that recommendation.

A result above 2.0 ng/mL in a non-anticoagulated patient warrants dietary assessment (is the patient on a low-fat diet that impairs fat-soluble vitamin absorption?), a check for fat malabsorption syndromes (celiac, IBD, short bowel), and consideration of supplementation. A result between 1.0 and 2.0 ng/mL in a woman on oral estrogen, or in any patient with low bone density or elevated CAC, should prompt repletion discussion.

Supplementation Targets and Re-Testing Intervals

When vitamin K2 (MK-7) supplementation is initiated at 180 mcg/day, PIVKA-II typically falls to below 1.0 ng/mL within 4 to 8 weeks in a patient with no fat-absorption issues. A 2014 randomized controlled trial in the British Journal of Nutrition (N=244, 3-year duration) demonstrated that MK-7 at 180 mcg/day reduced ucOC by 53% (P<0.001) and improved lumbar spine bone mineral density versus placebo. [12] PIVKA-II was not the primary endpoint in that trial, but mechanistically the two markers move together.

Re-test PIVKA-II 8 weeks after starting supplementation to confirm response. In premenopausal women, collect the follow-up sample in the same cycle phase as the baseline for valid comparison. A patient who does not respond to 180 mcg/day of MK-7 within 8 weeks should be evaluated for fat malabsorption rather than receiving automatic dose escalation.