Why the Tube Matters: Lithium Heparin 101

2 min read

8/13/26

Key Takeaways

Different tube additives exist because no single specimen type works for every test.
Lithium heparin stops clotting fast without disturbing the chemistry Rythm measures ideal for plasma panels shipped at ambient temperature.
Your one job: gentle inversions right after collection. Never shake.

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At-Home Testing

Why the Tube Matters: Lithium Heparin 101

2 min read

8/13/26

Key Takeaways

Different tube additives exist because no single specimen type works for every test.
Lithium heparin stops clotting fast without disturbing the chemistry Rythm measures ideal for plasma panels shipped at ambient temperature.
Your one job: gentle inversions right after collection. Never shake.

A Quick Tour of Tubes

Lithium heparin for many plasma chemistry tests. EDTA for complete blood counts and selected molecular tests. Sodium citrate for coagulation. Serum or serum-separator tubes for serum assays. Fluoride tubes for certain glucose testing. Tubes aren't interchangeable containers the additive determines what the sample can become.

Why Rythm Chose Lithium Heparin

Lithium heparin rapidly inhibits coagulation by neutralizing thrombin without strongly chelating calcium and magnesium preserving biochemical fidelity across a wide range of chemistry, lipid, thyroid, hormone, inflammation, and nutrient assays. It also means the lab can separate plasma without waiting for a clot to form. Hemoglobin (for men) is measured from the whole-blood portion before the rest is processed as plasma.

Keeping It Liquid

The anticoagulant dramatically reduces clotting during transport, but it needs your help to distribute: gently invert the capped tube as instructed right after collection. Gentle is the key word, vigorous shaking damages red cells and invites hemolysis. It's a ten-second step that protects your entire panel.

Frequently Asked Questions

How is Rythm different?

Most blood testing companies charge $500 or more for a single test per biomarker, providing only a one-time snapshot that doesn’t capture your long-term health trends or reflect your true baseline. This approach can lead to missed patterns or even misdiagnoses due to limited data. Rythm takes a different approach, using monthly tracking to build a detailed picture of your health over time. This allows for more accurate insights, better optimization, and a clearer understanding of how your body is evolving.

Does Rythm help me improve?

Rythm provides actionable suggestions and tips to help you optimize each biomarker

Is Rythm HIPAA compliant?

Yes, Rythm is HIPAA compliant. Your data is securely stored and handled in accordance with strict privacy and security standards.

Can I cancel anytime without fees?

Yes, you can cancel anytime without any fees.

Does Rythm accept HSA/FSA payments?

Yes, Rythm is HSA/FSA eligible. You can use your HSA or FSA card at checkout or submit your Rythm receipt to your provider for reimbursement.

How long does it take to get my results?

You will receive your results within 3 business days – as long as it's returned within 7 days of receiving your kit. Delays can occur if you do not send your sample back in time.