Biomarker Guide
By the UnitedWellness editorial team · Updated March 2026 · 10 min read
The comprehensive testing services covered in our lab testing comparison - Function Health, InsideTracker, Lifeforce - test dozens to over 100 biomarkers. More data isn’t automatically more useful. This guide focuses on the markers that have the strongest evidence for predicting long-term health outcomes and the most actionable implications when out of range.
Metabolic health markers
Metabolic dysfunction is an early and modifiable driver of cardiovascular disease, type 2 diabetes, and cognitive decline. These are among the most actionable markers available.
Fasting glucose - Blood sugar after 8+ hours without eating. Below 100 mg/dL is normal; 100–125 is prediabetic range; 126+ mg/dL on two draws is diagnostic for diabetes. Fluctuates with stress, illness, and sleep - a single reading should be interpreted with context.
HbA1c - Reflects average blood sugar over 2 to 3 months. A more stable indicator of metabolic trend than single glucose readings. Below 5.7% is normal; 5.7–6.4% is prediabetic. Responds well to dietary changes and exercise over several months.
Fasting insulin - Often the first marker to shift when insulin resistance is developing, sometimes years before glucose rises. Fasting insulin above 10 µIU/mL warrants attention; above 15 is significantly elevated. Not included in most standard panels - specifically worth requesting or using a service that includes it.
HOMA-IR - Calculated from fasting glucose and fasting insulin; a composite measure of insulin resistance. Some testing services calculate and report this automatically.
Cardiovascular risk markers
Cardiovascular disease remains the leading cause of death in the US. Several markers provide risk information beyond standard cholesterol panels.
ApoB - Measures the number of atherogenic (plaque-forming) lipoprotein particles rather than the weight of cholesterol. A better predictor of cardiovascular risk than LDL cholesterol for many people, particularly those with normal LDL but elevated small dense particles. Target below 80 mg/dL for low risk; below 60 mg/dL is increasingly recommended for high-risk individuals. Not included in standard panels but available through comprehensive services.
LDL cholesterol - Standard marker. Guideline targets vary by risk level, typically below 100 mg/dL for most adults and below 70 mg/dL for those with cardiovascular disease or high risk.
HDL cholesterol - Protective. Below 40 mg/dL in men and 50 mg/dL in women is a risk factor; above 60 mg/dL is considered protective.
Triglycerides - Strongly responsive to dietary carbohydrate and alcohol intake. Below 150 mg/dL is normal; above 200 mg/dL is elevated. A useful short-term feedback marker for dietary changes.
Lp(a) - Lipoprotein(a) is a genetically determined cardiovascular risk factor largely unresponsive to lifestyle modification. Elevated levels (above 50 mg/dL or 125 nmol/L depending on units) indicate significantly higher cardiovascular risk. Worth knowing, though current treatment options are limited. Included in comprehensive panels.
Inflammation markers
hs-CRP - High-sensitivity C-reactive protein reflects systemic inflammation. Below 1.0 mg/L is low risk; 1.0–3.0 mg/L is moderate; above 3.0 mg/L is elevated. Rises acutely with illness, injury, or stress - a single elevated reading should be repeated when healthy before drawing conclusions. Chronic elevation is meaningful.
Homocysteine - Elevated homocysteine (above 15 µmol/L) is associated with cardiovascular and cognitive risk. Responsive to B vitamin supplementation (B6, B12, folate) in many people - a relatively actionable marker when elevated. Not in standard panels; available through comprehensive services.
Hormonal markers
Testosterone (total and free) - For men, total testosterone below 300 ng/dL with symptoms suggests hypogonadism worth evaluating. Free testosterone is often more clinically meaningful. Test in the morning (before 10 AM) when levels peak. For women, testosterone is tested as part of broader hormonal evaluation, particularly when libido or fatigue are concerns.
DHEA-S - Adrenal androgen that declines with age. Low levels are associated with fatigue, reduced libido, and immune function. Can be supplemented, though supervision is appropriate.
Cortisol - Stress hormone. Morning cortisol should be relatively high; evening cortisol low. Dysregulated cortisol patterns affect sleep, metabolism, and immune function. Interpretation requires context - a single reading has limited meaning.
Estradiol and progesterone - For women, interpretation requires menstrual cycle phase context. Most meaningful when evaluated longitudinally alongside symptoms.
Thyroid function
TSH - Primary screening test. High TSH = underactive thyroid; low TSH = overactive. Standard range is roughly 0.5–4.5 mIU/L, though some clinicians use a narrower range for optimal function.
Free T4 and Free T3 - Active thyroid hormones. Typically added when TSH is abnormal or symptoms suggest thyroid dysfunction despite normal TSH.
Organ function markers
ALT and AST (liver enzymes) - Elevated levels suggest liver stress or damage. ALT is more liver-specific. Rises with alcohol use, fatty liver, and certain medications.
eGFR (estimated glomerular filtration rate) - Kidney filtration function. Derived from creatinine levels. Below 60 mL/min/1.73m² on repeated measurement warrants investigation.
Complete blood count (CBC) - Red blood cell, white blood cell, and platelet counts. Anemia, immune function signals, and blood production status. Baseline information that provides important clinical context.
Using comprehensive testing services
Services like Function Health, InsideTracker, and Lifeforce test many of these markers simultaneously and provide context for the results. The value of comprehensive testing is in seeing the full picture - individual markers tell partial stories, while patterns across categories tell more complete ones.
The most important thing to do with comprehensive test results is bring them to a clinician who can interpret them in the context of your full history - not just the flags generated by the testing service’s algorithm. See our lab testing services comparison for details on what each service covers and costs.