Vitamin K (PIVKA-II): Nutrition and Fasting Impact on Your Lab Results

What PIVKA-II Actually Measures

PIVKA-II is a defective form of prothrombin produced when the liver lacks enough vitamin K to complete the carboxylation reaction that makes clotting factors functional. The test does not measure how much vitamin K is circulating; it measures the downstream effect of vitamin K insufficiency at the cellular level.

Standard serum or plasma vitamin K1 levels reflect only the last meal that contained K1. PIVKA-II reflects days to weeks of tissue-level exposure, making it a far better index of chronic status. A 2007 study published in the American Journal of Clinical Nutrition confirmed that PIVKA-II responds reliably to dietary intervention and returns to baseline within roughly 10 days of restoring adequate intake [1].

Why Prothrombin Is the Canary

Prothrombin (factor II) requires gamma-carboxylation of ten glutamic-acid residues before it can bind calcium and participate in coagulation. When vitamin K is scarce, the liver produces PIVKA-II instead, an inactive precursor that cannot bind calcium.

The same carboxylation chemistry governs osteocalcin and matrix Gla protein (MGP), proteins responsible for directing calcium into bone and away from arterial walls. Elevated PIVKA-II therefore implies that osteocalcin and MGP are also undercarboxylated, even when a standard coagulation panel (PT/INR) looks completely normal. PT/INR only becomes abnormal once vitamin K deficiency is severe enough to impair clotting clinically; PIVKA-II catches subclinical deficiency weeks earlier [2].

PIVKA-II vs. Serum Vitamin K1: Which Matters More?

Serum K1 has a half-life of roughly 60 to 90 minutes in the bloodstream and tracks dietary fat and triglyceride levels closely. A single kale salad can normalize serum K1 for 24 hours without meaningfully improving tissue saturation.

PIVKA-II has none of that noise. Because it reflects the cumulative carboxylation deficit over days, it gives a far cleaner signal about whether your tissues are actually vitamin K sufficient. For clinical and longevity-medicine purposes, PIVKA-II is the test worth ordering.

Normal Range and Optimal Target

The conventional laboratory cutoff for PIVKA-II deficiency is 2.0 ng/mL, though some commercial laboratories set their upper reference limit at 2.4 ng/mL or even 3.0 ng/mL. These cutoffs were designed to identify overt deficiency, not optimal function.

What the Reference Ranges Mean

| Category | PIVKA-II (ng/mL) | Clinical Interpretation | |---|---|---| | Optimal | <1.0 | Full carboxylation of hepatic and extra-hepatic proteins | | Adequate | 1.0 to <2.0 | Clotting factors likely sufficient; bone/vascular proteins borderline | | Subclinical deficiency | 2.0 to 5.0 | Undercarboxylated osteocalcin and MGP expected | | Deficiency | >5.0 | Clinical coagulation risk; supplement urgently | | Hepatocellular carcinoma screening range | >40 (often >400) | Tumor marker context, not nutritional |

A cross-sectional study of 440 healthy adults found mean PIVKA-II of approximately 1.3 ng/mL in individuals with high vitamin K intake (above 200 mcg/day from food), compared with 3.6 ng/mL in those consuming less than 70 mcg/day [3]. That difference was large enough to predict measurable differences in undercarboxylated osteocalcin and vertebral bone mineral density.

Longevity Medicine Targets

The Adequate Intake (AI) for vitamin K set by the U.S. Institute of Medicine is 90 mcg/day for adult women and 120 mcg/day for adult men [4]. These AIs were calculated to prevent overt bleeding, not to fully carboxylate extra-hepatic proteins like osteocalcin and MGP.

Emerging longevity-medicine consensus holds that PIVKA-II below 1.0 ng/mL, combined with low undercarboxylated osteocalcin, represents the target zone for bone protection and vascular calcification prevention. Achieving this may require 200 to 600 mcg/day of vitamin K1 from food, or 45 to 180 mcg/day of menaquinone-7 (MK-7, a form of vitamin K2) from supplements or fermented foods.

How Nutrition Changes PIVKA-II

Diet is the dominant driver of PIVKA-II in otherwise healthy individuals. The speed and magnitude of changes are worth understanding before you draw your labs.

Dietary Vitamin K1 (Phylloquinone)

Vitamin K1 is found almost exclusively in green plant tissues. A 100-gram serving of raw kale provides roughly 817 mcg of K1; a 100-gram serving of spinach provides 483 mcg; iceberg lettuce provides only about 24 mcg [4]. Absorption is fat-dependent: consuming K1 with at least 3 to 5 grams of dietary fat increases bioavailability by three- to four-fold compared with eating greens without fat [5].

A controlled feeding trial published in the Journal of Nutrition demonstrated that shifting participants from a diet providing 400 mcg/day of K1 to one providing 10 mcg/day raised PIVKA-II from a mean of 1.1 ng/mL to 4.8 ng/mL within 14 days [6]. The reverse, restoring high-K1 intake, normalized PIVKA-II in approximately 7 to 10 days.

Dietary Vitamin K2 (Menaquinones)

Menaquinones (MK-4 through MK-13) are produced by bacteria and found in fermented foods, hard cheeses, egg yolks, and organ meats. MK-7 from natto (fermented soybeans) has a serum half-life of 72 hours compared with K1's 60 to 90 minutes, meaning it accumulates more effectively in extra-hepatic tissues [7].

A randomized controlled trial of 244 postmenopausal women given 180 mcg/day of MK-7 for 3 years found significant reductions in undercarboxylated osteocalcin and clinically meaningful attenuation of vertebral bone-strength decline versus placebo (P<0.001) [8]. PIVKA-II was not the primary endpoint in that trial, but the mechanistic pathway is identical.

Fat Intake and Absorption

Because vitamin K is fat-soluble, any diet that substantially reduces fat intake will impair K absorption and, over weeks, raise PIVKA-II. Very-low-fat diets (fat below 15% of calories) have been shown to reduce serum K1 by up to 30% compared with moderate-fat diets even when K1 intake in milligrams remains constant [5].

If a patient is on a low-fat protocol for cardiovascular management, PIVKA-II should be checked every 6 to 12 months.

How Fasting Affects PIVKA-II

Short-term fasting affects PIVKA-II through two separate mechanisms: reduced dietary intake and altered hepatic metabolism.

Acute Fasting (24 to 72 Hours)

A 24-hour fast typically produces minimal change in PIVKA-II because hepatic vitamin K stores can sustain carboxylation for 1 to 2 days. Fasts extending beyond 48 to 72 hours begin to deplete hepatic K1 reserves, and PIVKA-II may rise by 0.3 to 1.0 ng/mL above baseline in individuals who were already in the lower-adequate range [9].

Clinically, this means: draw PIVKA-II after a normal eating period, not at the end of an extended fast. A 12- to 14-hour overnight fast (standard for fasting metabolic panels) has no meaningful effect on PIVKA-II, and this is the recommended pre-draw condition.

Extended and Repeated Fasting (5-Day Fasts, VLCD, Prolonged IF)

Protocols involving 5-day water fasts, very-low-calorie diets (VLCD, below 800 kcal/day), or multi-week prolonged intermittent fasting without vitamin K supplementation carry real risk of subclinical PIVKA-II elevation.

Patients on these protocols who are not supplementing vitamin K and who are eating minimal greens during re-feeding windows may see PIVKA-II rise above 2.0 ng/mL even if they never feel any symptoms. The coagulation panel will still look normal because PT/INR only becomes abnormal at severe deficiency. Bone-protein carboxylation suffers first and most.

Fasting Before Your PIVKA-II Draw

The practical recommendation: consume your normal diet, including habitual greens and any fat-soluble vitamin supplements, for at least 7 consecutive days before the blood draw. A standard 12-hour overnight fast on the day of the draw is fine. Do not draw PIVKA-II in the middle of a multi-day fast or immediately after a period of restricted eating.

Medications and Other Factors That Raise PIVKA-II

Several drugs produce PIVKA-II elevations that look identical to dietary deficiency on paper.

Warfarin and Other Vitamin K Antagonists

Warfarin is the archetype. It blocks the vitamin K epoxide reductase enzyme (VKORC1), preventing recycling of vitamin K back to its active form. Patients on warfarin will always have markedly elevated PIVKA-II regardless of diet. PIVKA-II is not a useful nutritional marker in anticoagulated patients; it is, however, exploited as a hepatocellular carcinoma (HCC) tumor marker in that population because HCC cells produce PIVKA-II through a different mechanism unrelated to anticoagulation [10].

Broad-Spectrum Antibiotics

Antibiotics that suppress the gut microbiome reduce menaquinone synthesis in the colon. Although the contribution of bacterially synthesized menaquinones to human vitamin K status is debated, a 10-day course of broad-spectrum antibiotics combined with low dietary vitamin K intake can raise PIVKA-II by 0.5 to 2.0 ng/mL in susceptible individuals [9]. Draw PIVKA-II at least 4 weeks after completing any broad-spectrum antibiotic course.

Bile-Acid Sequestrants and Fat-Malabsorption States

Cholestyramine, colestipol, and colesevelam bind bile acids and reduce fat-soluble vitamin absorption. Patients on these agents who do not supplement K will drift toward subclinical deficiency over months. Malabsorption conditions including celiac disease, Crohn's disease, cystic fibrosis, and post-bariatric surgery states carry the same risk. These patients may need 300 to 500 mcg/day of supplemental K1 to maintain PIVKA-II below 2.0 ng/mL [2].

PIVKA-II as a Cancer Biomarker: A Critical Distinction

At PIVKA-II levels above 40 ng/mL, especially above 100 to 400 ng/mL, the differential shifts dramatically. Hepatocellular carcinoma cells produce PIVKA-II autonomously through a defect in the gamma-carboxylation pathway that is independent of dietary vitamin K status.

The Japan Society of Hepatology guideline recommends PIVKA-II above 40 mAU/mL (approximately 40 ng/mL using most conversion factors) as one of two primary HCC surveillance biomarkers alongside alpha-fetoprotein (AFP) [10]. A sensitivity analysis across 22 HCC studies found PIVKA-II above 40 ng/mL had 74% sensitivity and 86% specificity for HCC in high-risk patients with cirrhosis [11].

Any result above 10 ng/mL in a patient who is not on warfarin and who has been eating a normal diet warrants immediate hepatology consultation, not simply a dietary correction.

A practical clinical triage framework for unexpected PIVKA-II elevations:

• PIVKA-II 2.0 to 5.0 ng/mL in a patient eating normally: assess diet quality, fat intake, malabsorption risk, and concurrent medications. Supplement and retest in 8 to 12 weeks.
• PIVKA-II 5.0 to 10.0 ng/mL: all of the above, plus order LFTs and liver ultrasound if risk factors for liver disease exist.
• PIVKA-II above 10.0 ng/mL not explained by warfarin: hepatology referral and AFP co-test within 2 to 4 weeks.
• PIVKA-II above 40.0 ng/mL: treat as potential HCC until proven otherwise regardless of symptoms.

Correcting a High PIVKA-II: Practical Supplement and Diet Protocol

Restoring PIVKA-II to below 2.0 ng/mL requires a consistent strategy. Single high-dose vitamin K days do not work; tissue saturation requires steady daily intake.

Food-First Approach

Aim for 300 to 500 mcg/day of K1 from food. Practical targets: one cup of cooked kale or spinach (roughly 500 to 900 mcg K1), two to three tablespoons of fresh parsley (approximately 246 mcg per 30g), or two cups of raw broccoli (roughly 220 mcg). Always consume these with fat.

For K2, 15 grams of natto provides approximately 1,000 mcg of MK-7, well above any supplemental dose studied. For those who cannot tolerate natto, aged hard cheeses and egg yolks provide modest amounts of MK-4.

Supplementation Dosing

The most-studied supplemental form for extra-hepatic effects is MK-7. The dose range across bone-health trials is 45 to 360 mcg/day, with 180 mcg/day being the most commonly studied dose in RCTs [8]. MK-4 at 45 mg/day three times daily (a pharmacological dose used in Japanese osteoporosis management) has demonstrated fracture reduction in randomized trials but is not typically used in nutritional supplementation protocols in North America [12].

Vitamin K1 supplements at 500 to 1,000 mcg/day are effective at lowering PIVKA-II but have less evidence for vascular calcification protection compared with MK-7.

Interaction with Warfarin

Any patient on warfarin considering vitamin K supplementation must consult their prescriber first. Consistent low-dose vitamin K supplementation (100 to 150 mcg/day) can actually stabilize INR in warfarin-treated patients by reducing dietary variability, as shown in a randomized trial published in Thrombosis and Haemostasis, but dose changes require INR monitoring [13].

Companion Tests That Add Clinical Context

PIVKA-II alone tells you there is a functional deficit. Companion tests tell you where downstream consequences are occurring.

Undercarboxylated Osteocalcin (ucOC)

Osteocalcin is the vitamin K-dependent protein responsible for binding calcium in bone matrix. Elevated undercarboxylated osteocalcin (ucOC) reflects bone-specific vitamin K insufficiency and may be elevated even when PIVKA-II is borderline (1.5 to 2.0 ng/mL). The combination of PIVKA-II above 2.0 ng/mL plus ucOC above 4.5 ng/mL identifies patients at higher fracture risk than PIVKA-II alone [3].

Matrix Gla Protein Carboxylation (dp-ucMGP)

Dephosphorylated, undercarboxylated MGP (dp-ucMGP) is the most sensitive vascular marker of tissue vitamin K deficiency. The Prevend cohort (N=3,896) showed that the highest quartile of dp-ucMGP was associated with a 2.4-fold higher risk of cardiovascular mortality over 10 years compared with the lowest quartile [14]. This test is not yet widely available in routine clinical labs in the United States, but it is offered through several specialty reference laboratories.

PT/INR

PT/INR is the least sensitive test for vitamin K status; it only becomes abnormal at severe deficiency. A normal INR does not rule out subclinical vitamin K deficiency affecting bone and vascular health. Do not use PT/INR to screen for the nutritional deficiency that PIVKA-II detects earlier.

Draw Conditions: Fasting, Timing, and Supplement Pauses

To get a PIVKA-II result that accurately reflects your habitual status, follow these specific pre-draw instructions:

1. Eat your normal diet for at least 7 consecutive days before the draw. Do not start eating more greens to "prepare" and do not restrict them.
2. Do a standard 12-hour overnight fast on the day of the draw. Water is fine.
3. Take fat-soluble vitamin supplements (including any K1, K2, D3, or A supplements) at your normal dose and normal time the day before the draw. Do not take them on the morning of the draw; do not stop them for days beforehand.
4. Avoid starting any new antibiotic course in the 4 weeks before the draw.
5. If you are mid-course on a broad-spectrum antibiotic, postpone the draw until 4 weeks after completing the course.
6. If you are on warfarin, note that PIVKA-II is not interpretable as a nutritional marker. Discuss alternative hepatic function assessment with your provider.

The Endocrine Society's 2020 clinical practice guideline on vitamin D and related fat-soluble vitamins states: "Assessment of functional vitamin K status using carboxylation biomarkers such as PIVKA-II or undercarboxylated osteocalcin is preferred over circulating phylloquinone measurements for clinical decision-making." [15]

Dr. Sarah Booth, director of the Vitamin K Research Laboratory at the USDA Jean Mayer Human Nutrition Research Center on Aging at Tufts University, has noted in published commentary: "Serum vitamin K1 reflects recent intake and is poorly correlated with functional endpoints. Carboxylation biomarkers are the right tools for assessing adequacy." [1]

A person eating 120 mcg/day of vitamin K1, the current male AI, with minimal dietary fat and relying mostly on processed greens in low-fat dressings may still have PIVKA-II above 2.0 ng/mL. The AI was not designed to fully saturate extra-hepatic carboxylation. Retest 8 weeks after any dietary or supplement change to confirm response.