An app for blood biomarkers and fitness-tracker data
What to look for in an app for labs and fitness-tracker data, and how Depth currently uses supported Apple Health records.
Depth Journal articles are educational, general-wellness content. They are not medical advice, diagnosis, or treatment.
Raghav Dua Co-founder, Depth Your ferritin came back at 38 ng/mL. It’s sitting in a PDF inside your lab’s app, flagged green, inside the normal band, filed under fine. Two icons over, your ring’s app shows resting heart rate up 7 bpm this month and HRV sliding for three weeks straight. Both true, both on your phone, and nothing on either screen knows the other number exists. You’re the integration layer. You’re doing the join in your head, from memory, badly.
That’s the gap the search “an app that tracks blood biomarkers and fitness-tracker data” actually names. You bought the blood-biomarker panel. You bought the fitness tracker. What you don’t have is the one thing that would make them worth more together than apart: something reading them on the same screen, against the same clock. A dashboard that parks two feeds side by side and calls it integration won’t do it.
Why most apps track one and silo the other
Lab apps are built around the draw. A vial goes to a machine, a result comes back, it gets a reference range and a flag, and the app’s job ends there. The portal your hospital gave you is a filing cabinet for PDFs. It has never heard of your ring and was never meant to.
Wearable apps are built around the device. Oura, Apple Health, Whoop: steps, sleep stages, HRV, a readiness score every morning. They are very good at the thing strapped to your body and have no idea what your ApoB or HbA1c is. There’s no field for it.
The split is structural, not lazy. A continuous glucose monitor takes a reading about every five minutes; a blood draw is one timestamp a quarter. Those are different shapes of data, from different companies, sold on different business models. Nobody set out to silo your health. The architecture did it for them, and you’re left holding two half-pictures.
The honest steelman is the all-in-one health apps that do import both. Some let you upload a lab PDF and sync your ring. Useful, and a real step up. But open most of them and you find a blood tab and a wearable tab. You swipe between them. Importing two datasets into one app is not the same as reading them together. The numbers share a login, not a thought.
What an app that tracks blood biomarkers and fitness-tracker data should do
Four things, in order. Each is a verb the software has to perform, not a feature it can list.
One timeline. Every lab marker and every wearable stream on a single clock, so the week a number moved you can see what else was true that week. This is the load-bearing idea, and it’s worth its own read: putting labs and wearables on one timeline is what turns two archives into one record. Without it, the other three are impossible.
Cross-referenced. It puts two signals next to each other and asks a question neither raises alone. Ferritin 38, plus a 7 bpm rise in resting heart rate, plus three weeks of thin deep sleep, suggests that iron status may be worth discussing with a qualified clinician. It does not confirm that iron caused the recovery change.
Trend-aware. It grades the slope, not the dot. An hs-CRP of 1.1, then 2.0, then 3.1 mg/L across three draws is a finding, even though the first two clear every lab flag and the third only just crosses the 3.0 risk line. An app that re-flags each value against the population band and forgets the last one will wave that whole climb through.
Interpreted. It suggests one question or low-risk change to consider before your next draw. And when it hasn’t seen enough of your data, it says “not yet” instead of guessing. Charting four feeds in pretty colors and wishing you luck is not interpretation. The work is the qualified sentence at the end, not the graph.
How Depth reads bloodwork and wearables as one
Apple Health is Depth’s only current health-data connection. Depth reads user-authorized fitness and wellness records from Apple Health. Supported records can include signals such as HRV, resting heart rate, VO2 max, sleep, and glucose where those records are available in Apple Health. Another app or device may write records to Apple Health, but Depth still reads them from Apple Health; that does not create a direct Depth integration with Oura, Apple Watch, WHOOP, a CGM, or other hardware. Depth does not communicate with, control, or certify those devices.
On the blood side, markers can include ApoB, Lp(a), fasting insulin, hs-CRP, HbA1c, and ferritin. Where available, Depth may help arrange home collection through an independent partner. Availability depends on location and partner confirmation. The partner performs collection and testing and issues the clinical result. Depth is not the laboratory, phlebotomy provider, or diagnostic provider.
Here is a hypothetical example of what reading them together can show. A CGM export shows glucose rising 64 mg/dL after lunch while the last two HbA1c draws crept up. Put them on one clock and lunch becomes one hypothesis to test, not a confirmed cause. Change one part of the meal if appropriate, watch the glucose response, and use the next draw as a longer-term check.
The Depth Score summarizes supported blood and Apple Health data as one number you can open up and inspect, down to the markers and trends that influenced it. It is a fitness and wellness signal, not a diagnosis.
What to look for before you pick an app
You’re close to a decision, so here’s the checklist, not a recap. Hold any app you’re weighing against five questions:
- Does it ingest both your labs and the fitness and wellness records you can authorize?
- Does it put them on one timeline?
- Does it cross-reference them, or just let you tab between two screens?
- Does it grade the trend, or re-flag each value as if the last one never happened?
- Does it suggest a follow-up and admit what it cannot determine?
A “no” on three or four of these is a dashboard, not an analyst.
And one last thing the silo hides. Two apps, each showing a tidy column of in-range numbers, can both be right and still miss the only thing that matters: your personal slope, already bending, while every value stays inside a band drawn for a crowd. Reference ranges flag the tails of a population, not your baseline. The app worth paying for grades you against your own line, not everyone else’s.
That is the read Depth is built to support with bloodwork and user-authorized Apple Health records. Early access and the Founders Edition are at app.depth.fit.
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Apple Health is Depth's only current health-data connection. Depth reads your bloodwork and user-authorized fitness and wellness data from Apple Health, then reasons across it to tell you what actually matters. Depth does not directly communicate with, control, or certify wearable or medical hardware.