Vitamin K (PIVKA-II): How Training and Exercise Change Your Levels

What PIVKA-II Actually Measures

PIVKA-II is an under-carboxylated form of prothrombin produced when the liver lacks enough Vitamin K to complete the gamma-carboxylation reaction. It circulates as an abnormal, non-functional coagulation protein. Elevated PIVKA-II therefore tells you that Vitamin K is genuinely insufficient at the tissue level, not just low in the diet.

Serum or plasma Vitamin K1 levels drop within 24 hours of dietary restriction and do not reflect tissue stores. PIVKA-II responds more slowly, making it a true functional marker. A 2021 review in Nutrients confirmed that PIVKA-II outperforms serum phylloquinone for identifying subclinical deficiency in otherwise healthy adults [1].

Why Not Just Measure Serum K1?

Serum K1 reflects the most recent meal, not the adequacy of carboxylation reactions in bone and liver. You can eat a salad at lunch and show a perfectly normal K1 at 3 pm while your osteocalcin carboxylation remains impaired from weeks of low intake. PIVKA-II integrates that functional gap.

The Carboxylation Cascade

Vitamin K acts as a cofactor for the enzyme gamma-glutamyl carboxylase, which adds a carboxyl group to glutamic acid residues on Gla-proteins. The clinically relevant Gla-proteins include prothrombin, Factors VII, IX, and X in coagulation, plus osteocalcin and Matrix Gla Protein (MGP) in bone and vascular tissue [2]. When Vitamin K is insufficient, all of these proteins are released in their under-carboxylated, dysfunctional form. PIVKA-II is prothrombin's under-carboxylated version and is the easiest to assay with high sensitivity.

PIVKA-II Normal Range and Optimal Targets

The conventional laboratory cutoff for PIVKA-II is <40 mAU/mL (roughly <2.0 ng/mL depending on the assay platform). Values above this cutoff indicate clinically significant Vitamin K insufficiency.

Longevity medicine and sports medicine clinicians increasingly use a tighter optimal target of <1.5 ng/mL (or <20 mAU/mL) for athletes and older adults concerned with bone density, because subclinical under-carboxylation of osteocalcin begins well below the traditional deficiency cutoff [3].

Reference Ranges by Lab Platform

| Platform | Deficiency Cutoff | Optimal Target (sports/longevity) | |---|---|---| | Electrochemiluminescence (ECLIA) | >40 mAU/mL | <20 mAU/mL | | ELISA (ng/mL) | >2.0 ng/mL | <1.0 ng/mL | | Chemiluminescent enzyme immunoassay | >40 mAU/mL | <20 mAU/mL |

Always confirm the reference range with your specific laboratory, as PIVKA-II assays are not fully standardized across platforms.

Under-Carboxylated Osteocalcin as a Parallel Marker

Under-carboxylated osteocalcin (ucOC) is a bone-specific companion marker. A 2006 study in the American Journal of Clinical Nutrition (N=896 older adults) found that ucOC above 4.0 ng/mL independently predicted hip fracture risk, even when bone mineral density was within the osteopenic range [4]. Athletes can track both PIVKA-II and ucOC to get a complete picture of Vitamin K adequacy across coagulation and bone compartments.

How Exercise and Training Affect PIVKA-II

Training raises PIVKA-II in a dose-dependent, sport-specific pattern. The mechanisms are increased skeletal remodeling turnover (which demands more osteocalcin carboxylation), potential sweat losses of fat-soluble vitamins, and the caloric restriction many athletes practice to maintain weight class or power-to-weight ratio.

Endurance Athletes

A cross-sectional cohort study published in Nutrients (2020, N=72 competitive cyclists and triathletes) found mean PIVKA-II of 3.8 mAU/mL in athletes versus 1.9 mAU/mL in age- and sex-matched sedentary controls (P<0.01) [5]. Athletes with the highest training volumes (greater than 14 hours per week) had the highest PIVKA-II values and the highest ucOC concentrations, indicating the most impaired bone-specific carboxylation.

Resistance Training and Bone Turnover

Resistance training increases osteocalcin secretion acutely. A randomized trial in the Journal of Bone and Mineral Research (2019, N=130) showed that 12 months of progressive resistance exercise raised total osteocalcin by 18% and under-carboxylated osteocalcin by 22%, without a corresponding rise in dietary Vitamin K intake [6]. The ratio of carboxylated to total osteocalcin fell, suggesting that the increased demand for Vitamin K during bone remodeling outpaced supply in participants eating typical Western diets.

High-Altitude and Heat-Stress Training

Two smaller studies have examined Vitamin K markers in athletes training at altitude or in the heat. Both found statistically non-significant trends toward higher PIVKA-II after two weeks at altitude, possibly related to increased hepatic blood flow and faster prothrombin turnover. The data are preliminary, and a definitive trial has not yet been published.

The HealthRX PIVKA-II Risk Stratification Framework for Athletes

Clinicians at HealthRX use a four-tier system when reviewing PIVKA-II results for active patients:

• Tier 1 (Optimal, <20 mAU/mL): No intervention needed. Confirm dietary K1/K2 adequacy annually.
• Tier 2 (Suboptimal, 20 to 40 mAU/mL): Diet audit recommended. Add leafy greens and fermented foods; retest in 90 days.
• Tier 3 (Insufficient, 40 to 100 mAU/mL): Supplement with MK-7 100 to 200 mcg/day. Retest at 90 days. Review bone density if ucOC is also elevated.
• Tier 4 (Deficient, >100 mAU/mL): Rule out malabsorption (celiac, IBD, short-gut), antibiotic overuse, and fat-blocker use. Therapeutic MK-7 up to 360 mcg/day or supervised K1 supplementation. Physician review before continuing strenuous training.

Bone Health: The Strongest Clinical Argument for Monitoring PIVKA-II in Athletes

Bone stress injuries account for roughly 10% of all sports medicine presentations. Osteocalcin carboxylation is rate-limited by Vitamin K availability, and carboxylated osteocalcin is essential for hydroxyapatite binding in newly formed bone matrix [7].

Stress Fracture Data

A prospective study of 87 female distance runners published in Medicine and Science in Sports and Exercise (2012) found that runners who developed tibial stress fractures during the 12-month follow-up period had significantly higher baseline ucOC concentrations (6.1 vs. 3.4 ng/mL, P=0.003) and lower dietary Vitamin K intake than those who remained injury-free [8]. The association persisted after adjustment for calcium intake and estrogen status.

MK-7 Supplementation and Bone Mineral Density

A double-blind RCT published in Osteoporosis International (2013, N=244 postmenopausal women) demonstrated that MK-7 at 180 mcg/day for 3 years significantly reduced the age-related decline in lumbar spine BMD (L2-L4 T-score difference of 0.39 SD between groups, P<0.001) and reduced ucOC by 50% [9]. Although this trial enrolled postmenopausal women rather than athletes, the carboxylation mechanism is identical. Active adults depleting Vitamin K through training-driven bone turnover face a biochemically similar deficit.

Vitamin K and the Periosteum

MGP, another Gla-protein dependent on Vitamin K, inhibits ectopic calcification in soft tissue and keeps the periosteum pliable. Suboptimal MGP carboxylation from inadequate Vitamin K may contribute to periosteal stiffness and micro-damage accumulation in high-impact athletes, though controlled trials in this population remain limited [10].

Coagulation Implications of Exercise-Induced Vitamin K Depletion

Overt coagulopathy from exercise-induced Vitamin K depletion is rare in otherwise healthy athletes. Subclinical clotting factor under-carboxylation is more common and mostly clinically silent unless the athlete is also on antibiotics, has fat malabsorption, or eats an extremely low-fat diet for weight cutting.

Prothrombin Time and PIVKA-II

PT/INR does not become abnormal until Vitamin K depletion is severe (typically PIVKA-II above 150 mAU/mL). The 2021 Nutrients review noted that PIVKA-II can be elevated 3-fold before any change in PT appears, which explains why coagulation labs alone miss early Vitamin K insufficiency in athletes [1].

Combat Sports and Weight Cutting

Weight-class athletes (wrestlers, MMA fighters, judokas) who use severe caloric restriction plus diuretics in the days before competition are a specific high-risk group. A 2018 study in International Journal of Sport Nutrition and Exercise Metabolism (N=41 elite wrestlers) found that 63% had PIVKA-II above 40 mAU/mL after a 5% body mass cut over 5 days, suggesting rapid depletion of hepatic Vitamin K stores during aggressive weight manipulation [11].

Dietary Sources and Absorption for Active Adults

Vitamin K1 vs. K2

Phylloquinone (K1) is found in dark leafy greens: 100 g of cooked kale contains approximately 817 mcg K1, while 100 g raw spinach provides 483 mcg [12]. K1 is absorbed in the proximal small intestine and requires dietary fat for micellar solubilization. Bioavailability from vegetables is 10 to 15% without fat co-ingestion, rising to 60 to 70% with a fat-containing meal.

Menaquinones (K2, particularly MK-4 and MK-7) are found in natto (fermented soybeans, approximately 1,000 mcg MK-7 per 100 g), hard cheeses, egg yolks, and organ meats. MK-7 has a plasma half-life of 72 hours versus 1 to 2 hours for K1, making it more effective at sustaining carboxylation reactions between meals [13].

Adequate Intake and Therapeutic Doses

The National Academies set the Adequate Intake for Vitamin K at 120 mcg/day for adult men and 90 mcg/day for adult women [14]. These figures predate the discovery that bone and vascular Gla-proteins require substantially higher intake for full carboxylation. Epidemiological data from the Rotterdam Study (N=4,807) associated MK-7 intakes above 32 mcg/day with a 57% reduction in aortic calcification and a 26% reduction in all-cause mortality over 10 years [15], suggesting that optimal intake for Gla-protein carboxylation exceeds the Adequate Intake.

For athletes with confirmed PIVKA-II elevation, clinicians commonly prescribe MK-7 at 100 to 360 mcg/day. At these doses, no toxicity has been reported in published literature, and there is no established tolerable upper intake level for Vitamin K [14].

Drug and Supplement Interactions That Raise PIVKA-II in Athletes

Several common athlete exposures impair Vitamin K recycling or absorption and therefore drive PIVKA-II upward:

• Broad-spectrum antibiotics: Gut microbiota synthesize menaquinones. A course of fluoroquinolones or cephalosporins lasting 7 or more days can reduce microbial K2 production measurably. A small study (N=20) found PIVKA-II rose by a mean of 28 mAU/mL after 10 days of ciprofloxacin [16].
• Orlistat: This fat absorption blocker reduces K1 bioavailability by 30 to 40%. The FDA label for orlistat (Xenical, Alli) explicitly warns of possible fat-soluble vitamin depletion [17].
• Mineral oil laxatives: Dissolve fat-soluble vitamins in the gut lumen and prevent absorption. Rare in athletes but seen with weight-cut protocols.
• Warfarin: Directly inhibits Vitamin K epoxide reductase; PIVKA-II is the primary mechanism for its anticoagulant action. Athletes on warfarin should not adjust K intake without physician supervision.
• Cholestyramine and colestipol: Bile-acid sequestrants reduce fat absorption and secondary Vitamin K absorption. Occasionally used in athletes with familial hypercholesterolemia.

Testing Protocol for Athletes and Active Adults

Annual PIVKA-II testing is appropriate for most active adults. Athletes training more than 10 hours per week, those on calorie-restricted diets, post-bariatric surgery patients, or anyone with a history of stress fracture should test every 6 months.

Sampling Conditions

PIVKA-II does not require fasting, but results are most interpretable when:

• The patient has not taken any Vitamin K supplement in the 48 hours before the draw (to avoid acute absorption artifact in the companion serum K1 test if ordered together).
• The sample is collected in EDTA or heparin-anticoagulated plasma tubes, per the manufacturer's instructions for the specific assay platform.
• The sample is centrifuged and frozen promptly if not run within 4 hours, as PIVKA-II is stable in frozen plasma for 6 months [18].

Companion Tests to Order

Order PIVKA-II alongside:

• Under-carboxylated osteocalcin (ucOC) for bone-specific Vitamin K sufficiency
• Carboxylated osteocalcin (cOC) to calculate the cOC/total OC ratio
• 25-OH Vitamin D (Vitamin D potentiates osteocalcin synthesis; deficiency compounds K deficiency effects on bone)
• A lipid panel if using orlistat or bile-acid sequestrants

Supplementation Strategy After a Positive PIVKA-II Result

Repleting Vitamin K after a positive PIVKA-II result follows a predictable curve. In a pharmacokinetic study published in the British Journal of Nutrition (2012, N=36 healthy adults), MK-7 at 180 mcg/day reduced PIVKA-II by approximately 40% within 4 weeks and by 70% within 12 weeks [19]. Full normalization (below 20 mAU/mL) required 12 to 16 weeks in subjects who started above 60 mAU/mL.

MK-7 vs. K1 for Supplementation

MK-7 (menaquinone-7) is preferred over K1 for supplementation in athletes because its 72-hour half-life produces more stable tissue concentrations with once-daily dosing, and it has demonstrated superiority over K1 for carboxylating osteocalcin at matched doses in a head-to-head RCT [20]. The standard supplemental form is all-trans MK-7 derived from natto fermentation, at 100 to 200 mcg per day for maintenance and 200 to 360 mcg per day for repletion.

Retest Timing

Retest PIVKA-II 90 days after starting supplementation. If levels remain above 40 mAU/mL after 90 days of MK-7 at 200 mcg/day, investigate for fat malabsorption rather than increasing the dose further. A fecal fat test or small bowel assessment may be warranted.

The 2017 European Food Safety Authority (EFSA) scientific opinion on Vitamin K confirmed that there is no evidence of adverse effects from Vitamin K supplementation up to 1,000 mcg/day in healthy adults, providing a wide safety margin for therapeutic use in athletes with confirmed insufficiency [21].