Medicine reacts. We test for answers.
Most labs tell you whether you're sick. Zaro tells you what's developing, what's at the root, and how your biology is aging, so you can act years before a diagnosis.
No other testing platform offers all three tiers of the cascade. Each level answers a fundamentally different question about your health.
Has something already gone wrong?
Surface
Body Systems Covered
The Science
Surface testing captures what has already crossed clinical thresholds. These are the markers standard medicine looks at during a routine physical, but that most people never get done as a full panel — the red flags that, caught early, prevent the most common causes of preventable death: heart disease, type 2 diabetes, thyroid dysfunction and anemia.
Who It's For
Anyone who has never had comprehensive bloodwork done, adults over 25 who want a baseline, or anyone who has not had labs in over two years.
Biomarkers Included
Metabolic Core
- Comprehensive Metabolic Panel — glucose, BUN, creatinine, eGFR, BUN/creatinine ratio, sodium, potassium, chloride, CO₂, calcium, total protein, albumin, globulin, A/G ratio, total bilirubin, ALP, AST, ALT (18 values)
- CBC with Differential and Platelets — WBC, RBC, hemoglobin, hematocrit, MCV, MCH, MCHC, RDW, platelets, MPV, plus neutrophils, lymphocytes, monocytes, eosinophils and basophils as both percentage and absolute count (20 values)
- HbA1c (glycated hemoglobin)
- Fasting insulin
- Uric acid
Heart & Lipids
- Lipid Panel with Reflex to Direct LDL — total cholesterol, LDL, HDL, triglycerides, non-HDL cholesterol, total/HDL ratio (6 values)
- hs-CRP (high-sensitivity C-reactive protein)
Advanced Cardiometabolic
- ApoB (apolipoprotein B)
Thyroid
- TSH (thyroid stimulating hormone)
Nutrients
- Vitamin D (25-OH)
- Ferritin
Urinalysis
- Complete Urinalysis with Microscopy and Reflex to Culture — color, appearance, specific gravity, pH, protein, glucose, ketones, occult blood, bilirubin, nitrite, leukocyte esterase, plus WBC and RBC per high-power field (13 values)
Is something developing?
Signal
Body Systems Covered
The Science
Signal markers are the early-warning system of preventive medicine. Where Surface markers respond to disease that has already developed, these detect the conditions that lead to it. Fasting insulin rises years before HbA1c signals pre-diabetes, and NMR fractionation finds dangerous particle patterns a standard lipid panel reports as normal.
Who It's For
Health optimizers, athletes, anyone with a family history of cardiovascular or metabolic disease, and anyone who has done Surface and wants to go deeper.
What Signal Adds
Advanced Cardiometabolic
- Lipoprotein(a) — inherited cardiovascular risk
- Lipoprotein Fractionation by NMR — LDL-P, small LDL-P, LDL peak size, HDL-P, HDL peak size, large VLDL-P, VLDL peak size (7 values)
- Homocysteine
Hormones
- Testosterone — total, free and bioavailable, with SHBG, by mass spectrometry (4 values) — men
- DHEA-S (dehydroepiandrosterone sulfate) — men
- Estradiol (E2) — women
- LH (luteinizing hormone) — women
- FSH (follicle stimulating hormone) — women
- Progesterone — women
- Cortisol, AM — adrenal function
Extended Thyroid
- Free T3 (free triiodothyronine)
- Free T4 (free thyroxine)
Nutrients
- Vitamin B12
- Iron, TIBC and Ferritin Panel — iron, total iron-binding capacity, % saturation (3 values)
- Magnesium
Metabolic Depth
- Folate, serum
- Zinc
- GGT (gamma-glutamyl transferase)
Advanced Kidney
- Albumin, Random Urine with Creatinine — urine albumin, urine creatinine, albumin/creatinine ratio (3 values)
What root causes?
Source
Body Systems Covered
The Science
Source reaches the upstream causes Signal does not capture: autoimmune thyroid activity, systemic inflammatory load, coagulation risk and the omega-3 status that shapes how you age. It is also the tier that unlocks Biological Age (PhenoAge) and Heart Age (AHA PREVENT), two independent reads on how your biology is ageing relative to your years.
Who It's For
Longevity-focused members, anyone with chronic fatigue, hormonal symptoms or unresolved issues, and anyone who has completed Signal and wants root causes.
What Source Adds
Advanced Cardiometabolic
- Fibrinogen activity — coagulation and inflammation risk
- OmegaCheck — EPA, DPA, DHA, omega-3 total, omega-6 total, arachidonic acid, linoleic acid, omega-6:omega-3 ratio, AA/EPA ratio (9 values)
Extended Thyroid
- TPO antibodies (thyroid peroxidase)
- Thyroglobulin antibodies
Autoimmune & Inflammation
- ESR (erythrocyte sedimentation rate)
Cognitive Risk
- Vitamin B1 (thiamine), whole blood by LC/MS/MS
Metabolic Depth
- HOMA-IR — insulin resistance index, calculated from fasting glucose and insulin
Two ages. One clock.
Zaro calculates your Biological Age (PhenoAge), reflecting how old your body actually is based on blood chemistry, and your Heart Age using the AHA PREVENT model. Is your biology aging faster or slower than your birthday suggests?
Chronological Age
38Biological Age
PhenoAge Model
Heart Age
AHA PREVENT
Example output · your results will reflect your actual blood data
A living health score, built on three pillars
Zaro synthesizes bloodwork, wearable signals, and lifestyle into a single score out of 100. It updates continuously and adapts to whatever data you have, no wearable required to get started.
Score Bands
Adaptive weighting
Score adapts automatically as you add data
Full data
Labs + wearable + lifestyle
No wearable
Labs re-weighted with lifestyle
Labs only
Biomarker Score shown
Start knowing your body.
Choose a panel, schedule your blood draw, and get answers that actually explain what is happening inside your body.