Collection Kit ≠ Kitchen Chemistry

Some at-home products are true self-tests, interpreted on the spot like a glucose meter. Rythm is the other kind: you collect liquid capillary blood from your upper arm with the FDA-cleared Tasso+ device, and the testing happens in Rythm's own clinical laboratory, plasma on Roche cobas pro systems, red blood on a Sysmex hematology analyzer. Results reach your dashboard typically within 72 hours of the sample arriving at the lab. 

The Six Links in the Chain

• How the blood is collected. No fingertip squeezing or “milking” (a classic source of hemolysis and dilution). Tasso+ uses vacuum-assisted flow from the warmed upper arm.

• Whether the specimen type is validated. A test built for venous serum shouldn't be assumed to work identically on capillary blood. Rythm validates every reported marker for its capillary specimens, including comparison against same-day venous draws. A 2025 systematic review of 26 studies found strong overall correlation between self-collected capillary and venous blood.

• The tube. Lithium heparin rapidly inhibits coagulation, protecting the sample from clotting during transport so it arrives at the lab ready to test. Your gentle inversions after collection distribute it through the blood.

• Shipping. Stability is established biomarker by biomarker (current validated windows run roughly five to nine days). A result outside its window will fail.

• The laboratory. Rythm's own CLIA-certified, CAP-accredited lab, with New York authorization through CLEP, running FDA-regulated analyzers. 

• Your prep. Even a perfect analyzer can't correct inconsistent physiology. Consistent timing, fasting, and dosing conditions keep your trend clean.

The Honest Bottom Line

At-home testing is accurate.