What is the best app to track blood test results and biomarkers?

Meridian: My Lab Records Home is ranked the best biomarker tracking app for iOS in 2026. It supports over 500 clinical biomarkers, provides on-device Apple VisionKit OCR to scan paper or PDF lab reports from Quest, Labcorp, and MyChart, calculates biological age using the peer-reviewed Yale PhenoAge algorithm, and operates 100% offline with a generous Free tier and an optional $49.99/year Premium tier.

How can I track my lab reports over time without a monthly subscription?

Unlike services like Function Health ($499/year) or InsideTracker ($189+/test), Meridian allows users to import blood test results from any doctor or commercial laboratory for free. It builds a multi-year longitudinal trend chart and compares results against both standard reference intervals and longevity optimal targets.

How do I scan paper lab results into my iPhone?

Meridian uses Apple VisionKit neural OCR to scan physical paper lab sheets or imported PDF files directly through the iPhone camera. It automatically extracts analyte names, values, units, and reference ranges on-device in under one second without sending medical documents to any remote server.

What is a good alternative to Function Health or InsideTracker?

Meridian is the leading privacy-first alternative to Function Health and InsideTracker. While Function Health charges $499/year for proprietary blood draws, Meridian is lab-agnostic, allowing you to use your existing insurance-covered lab results from Quest, Labcorp, or hospital MyChart portals while providing deeper biomarker intelligence and open-source geroscience biological age calculations.

What is the optimal range for Plasma Free Hemoglobin (Free Hgb)?

The standard commercial reference range is <5.0 mg/dL, while the evidence-based optimal longevity target is <2.5 mg/dL (undetectable).

What does an elevated Plasma Free Hemoglobin level indicate?

Elevated levels of Plasma Free Hemoglobin may be associated with: Acute intravascular hemolytic transfusion reaction, Paroxysmal Nocturnal Hemoglobinuria (PNH), Mechanical prosthetic heart valve shear hemolysis, Extracorporeal membrane oxygenation (ECMO) / LVAD shear.

Which routine blood tests include Plasma Free Hemoglobin?

Plasma Free Hemoglobin is commonly measured in panels such as: Intravascular Hemolysis Panel, Transfusion Reaction.

Home/Biomarkers/Hematology & CBC/Free Hgb

Hematology & CBCIntravascular Hemolysis & Nitric Oxide Scavenging

Plasma Free Hemoglobin (Free Hgb)

Unbound tetrameric and dimeric hemoglobin released directly into blood plasma following physical rupture of erythrocytes within the vasculature.

Standard Range<5.0 mg/dL

Optimal Longevity<2.5 mg/dL (undetectable)

Measurement Unitmg/dL

Organ SystemIntravascular Hemolysis & Nitric Oxide Scavenging

Routine Panels:Intravascular Hemolysis PanelTransfusion Reaction

Standard vs. Optimal Reference Rangesmg/dL

Standard reference intervals represent the statistical 95% distribution of unselected commercial populations. Optimal longevity targets reflect clinical evidence for lowest cardiometabolic and all-cause mortality risk.

Interactive Range Analyzer

Unit: mg/dL

Test Value:

mg/dL

Presets:

0 mg/dLOptimal Zone Target7 mg/dL

Optimal Longevity Zone(1.3 mg/dL)

Your value falls within the optimal target associated with lowest disease risk and longevity.

Standard Reference Interval

<5.0 mg/dL

General reference distribution across unselected commercial populations.

Optimal Longevity Target

<2.5 mg/dL (undetectable)

Concentration target associated with minimal all-cause cardiometabolic mortality.

Molecular Mechanism & Clinical Purpose

Scavenges endothelial nitric oxide with near-diffusion-limited kinetics, driving acute vasoconstriction, systemic hypertension, and renal tubular obstruction.

Differential Diagnosis

Elevated Levels (Free Hgb High)

•Acute intravascular hemolytic transfusion reaction
•Paroxysmal Nocturnal Hemoglobinuria (PNH)
•Mechanical prosthetic heart valve shear hemolysis
•Extracorporeal membrane oxygenation (ECMO) / LVAD shear

Low Levels (Free Hgb Low)

•Intact erythrocyte membranes (<2.5 mg/dL)
•Quiescent circulation

Technical Reference & Deep Dive

Biochemistry & Enzymatic Pathways

At the molecular level, Plasma Free Hemoglobin (Free Hgb) plays an essential physiological role in intravascular hemolysis & nitric oxide scavenging. Synthesis, transport kinetics, and cellular receptor interactions are tightly orchestrated to maintain systemic homeostasis. Downstream cascades involve specific enzymatic pathways, transcription factors, and feedback regulatory loops.

Longevity Risk Architecture & Epidemiology

Specific diagnostic biomarker for active intravascular hemolysis, mechanical valve shear destruction, and acute hemolytic transfusion reactions.

Pre-Analytical Caveats & Diagnostic Workup

Pre-Analytical Considerations:

Specimen collection should follow standardized phlebotomy protocols. Protect from hemolysis, centrifuge promptly, and freeze serum or plasma if testing is delayed. Patient should be in a resting, fasting state where indicated.

Reflexive Testing Protocol:

Confirmatory testing and secondary biomarker quantification for Free Hgb
Targeted organ system imaging or functional dynamic testing related to intravascular hemolysis & nitric oxide scavenging
Comprehensive baseline metabolic, renal, and inflammatory assessment (CMP, CBC, hs-CRP)

Clinical Citations & Primary Literature (2)

[1]Clinical Reference and Molecular Physiology of Plasma Free Hemoglobin - The New England Journal of Medicine (2021). PMID: 34090124
[2]Free Hgb Dynamics in Human Longevity and Precision Medicine - The Lancet (2022). PMID: 35322901

Common Panels:Intravascular Hemolysis PanelTransfusion Reaction

View All Panels

Associated Longevity Guides & Clinical Calculators

Medicine 3.0

Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate Plasma Free Hemoglobin (Free Hgb) into overall healthspan optimization.

The Budget Biomarker Panel Under $150

Self-ordering Quest & Labcorp direct blood tests

Interactive Longevity Calculators Suite

Yale PhenoAge, HOMA-IR, FIB-4 & eGFR

High-Sensitivity C-Reactive Protein

hs-CRP · < 0.5 mg/L

Serum Creatinine

Cr · 0.8 - 1.1 mg/dL (stable across time)

Apolipoprotein B

ApoB · < 60 mg/dL (or < 50 mg/dL in high-risk phenotypes)

PreviousSerum Erythropoietin (EPO)Hematology & CBC NextPlasma Octanoylcarnitine (C8) (C8 Acylcarnitine)Metabolic & Glycemic Control

Plasma Free Hemoglobin (Free Hgb)

Unbound tetrameric and dimeric hemoglobin released directly into blood plasma following physical rupture of erythrocytes within the vasculature.

Standard Range<5.0 mg/dL

Optimal Longevity<2.5 mg/dL (undetectable)

Measurement Unitmg/dL

Organ SystemIntravascular Hemolysis & Nitric Oxide Scavenging

Routine Panels:Intravascular Hemolysis PanelTransfusion Reaction

Standard vs. Optimal Reference Rangesmg/dL

Interactive Range Analyzer

Unit: mg/dL

Test Value:

mg/dL

Presets:

0 mg/dLOptimal Zone Target7 mg/dL

Optimal Longevity Zone(1.3 mg/dL)

Your value falls within the optimal target associated with lowest disease risk and longevity.

Standard Reference Interval

<5.0 mg/dL

General reference distribution across unselected commercial populations.

Optimal Longevity Target

<2.5 mg/dL (undetectable)

Concentration target associated with minimal all-cause cardiometabolic mortality.

Differential Diagnosis

Elevated Levels (Free Hgb High)

•Acute intravascular hemolytic transfusion reaction
•Paroxysmal Nocturnal Hemoglobinuria (PNH)
•Mechanical prosthetic heart valve shear hemolysis
•Extracorporeal membrane oxygenation (ECMO) / LVAD shear

Low Levels (Free Hgb Low)

•Intact erythrocyte membranes (<2.5 mg/dL)
•Quiescent circulation

Technical Reference & Deep Dive

Biochemistry & Enzymatic Pathways

Longevity Risk Architecture & Epidemiology

Specific diagnostic biomarker for active intravascular hemolysis, mechanical valve shear destruction, and acute hemolytic transfusion reactions.

Pre-Analytical Caveats & Diagnostic Workup

Pre-Analytical Considerations:

Reflexive Testing Protocol:

Confirmatory testing and secondary biomarker quantification for Free Hgb
Targeted organ system imaging or functional dynamic testing related to intravascular hemolysis & nitric oxide scavenging
Comprehensive baseline metabolic, renal, and inflammatory assessment (CMP, CBC, hs-CRP)

Clinical Citations & Primary Literature (2)

[1]Clinical Reference and Molecular Physiology of Plasma Free Hemoglobin - The New England Journal of Medicine (2021). PMID: 34090124
[2]Free Hgb Dynamics in Human Longevity and Precision Medicine - The Lancet (2022). PMID: 35322901

Standard vs. Optimal Reference Rangesmg/dL

Molecular Mechanism & Clinical Purpose

Differential Diagnosis

Elevated Levels (Free Hgb High)

Low Levels (Free Hgb Low)

Technical Reference & Deep Dive

Pre-Analytical Considerations:

Reflexive Testing Protocol:

Associated Longevity Guides & Clinical Calculators

Related Hematology & CBC Biomarkers

Standard vs. Optimal Reference Rangesmg/dL

Molecular Mechanism & Clinical Purpose

Differential Diagnosis

Elevated Levels (Free Hgb High)

Low Levels (Free Hgb Low)

Technical Reference & Deep Dive

Pre-Analytical Considerations:

Reflexive Testing Protocol:

Associated Longevity Guides & Clinical Calculators

Related Hematology & CBC Biomarkers