What is soluble transferrin receptor (sTfR)?
Transferrin receptors sit on cell surfaces and bind transferrin (the protein that carries iron in the blood) to bring iron into cells. A portion of these receptors circulates in blood as soluble transferrin receptor (sTfR). When your body senses that iron supply to tissues is insufficient (or when bone marrow is ramping up red blood cell production), transferrin receptor expression increases, and sTfR tends to rise.
Why it’s tested
sTfR is commonly used to:
-
Detect iron deficiency (including earlier/functional stages)
-
Support evaluation of anemia (especially when ferritin may be distorted by inflammation)
-
Assess iron-restricted erythropoiesis (not enough usable iron for red blood cell production)
-
Add context alongside ferritin, serum iron, transferrin saturation (TSAT), CBC indices (MCV/MCH), and inflammatory markers (CRP)
What a high result can mean (above range)
A high sTfR usually suggests increased cellular demand for iron, most commonly due to iron deficiency. It can also rise when the bone marrow is producing more red blood cells than usual.
Common causes include:
-
Iron deficiency from low intake or absorption (low iron diet, celiac disease, bariatric surgery, chronic gastritis, H. pylori, long-term acid suppression in some cases)
-
Chronic blood loss (heavy periods, frequent blood donation, GI bleeding)
-
Increased requirements (pregnancy, growth, endurance training in some people)
-
Increased red blood cell production (hemolysis, treatment response to iron or EPO, recovery from blood loss)
-
Some hematologic conditions with high erythropoiesis (interpret with a clinician)
Typical symptoms that can fit iron deficiency (not specific):
-
Fatigue, reduced exercise tolerance, shortness of breath on exertion
-
Headaches, dizziness
-
Cold intolerance
-
Restless legs, poor sleep
-
Hair shedding, brittle nails
-
Palpitations
-
Pica (craving ice/clay)
What to do next (practical steps):
-
Review a full iron workup: ferritin, serum iron, TIBC/transferrin, TSAT
-
Check a CBC (hemoglobin/hematocrit, MCV/MCH/RDW) and consider reticulocyte count
-
If inflammation is suspected, add CRP (and sometimes ESR)
-
If iron deficiency is likely, identify the source: menstrual losses, GI symptoms, diet, absorption issues
-
Discuss iron repletion strategy (dietary iron, oral iron timing, or IV iron when appropriate) with your clinician
What a low result can mean (below range)
Low sTfR is generally less common and often reflects lower demand for iron uptake or reduced red blood cell production.
Possible causes include:
-
Adequate iron status with stable red blood cell production (sometimes simply normal physiology)
-
Reduced bone marrow activity (various chronic illnesses or marrow suppression—interpret in clinical context)
-
Some cases of kidney disease or endocrine issues affecting erythropoiesis (context-dependent)
-
Recent transfusion or conditions where erythropoiesis is suppressed (context-dependent)
If sTfR is low and anemia is present, it’s important to evaluate:
-
CBC pattern (MCV, RDW), reticulocytes
-
Inflammation markers (CRP)
-
Kidney function (creatinine/eGFR), thyroid function (TSH) if clinically indicated
-
B12/folate if macrocytosis or neurologic symptoms are present
How to interpret sTfR with other iron markers
-
Ferritin reflects iron stores but can rise with inflammation; sTfR is often less influenced by inflammation.
-
TSAT reflects circulating available iron; low TSAT with high sTfR supports iron-restricted supply.
-
sTfR/log ferritin index (or “sTfR-ferritin index”) is sometimes used to distinguish iron deficiency from anemia of inflammation, depending on the lab and units.
Important notes
-
Reference ranges and units vary by lab, and sTfR assays are not fully standardized across all platforms, so trends and context matter.
-
Interpretation is strongest when combined with CBC, ferritin, TSAT, and CRP.
What does it mean if your Soluble Transferrin Receptor result is too high?
A high soluble transferrin receptor (sTfR) level most often suggests iron deficiency or insufficient usable iron for red blood cell production, even when ferritin is hard to interpret during inflammation. Confirm with ferritin and transferrin saturation (TSAT), review symptoms (fatigue, exercise intolerance, hair shedding, restless legs), and work with a clinician to identify causes such as blood loss or absorption issues and to choose an appropriate iron repletion plan.
All Your Lab Results.
One Simple Dashboard.
Import, Track, and Share Your Lab Results Easily
Import, Track, and Share Your Lab Results
Import lab results from multiple providers, track changes over time, customize your reference ranges, and get clear explanations for each result. Everything is stored securely, exportable in one organized file, and shareable with your doctor—or anyone you choose.
Cancel or upgrade anytime
What does it mean if your Soluble Transferrin Receptor result is too low?
A low soluble transferrin receptor (sTfR) level generally reflects reduced cellular demand for iron, most often because red blood cell production in the bone marrow is stable or reduced. In many healthy individuals, a low sTfR can simply indicate adequate iron availability and balanced red blood cell turnover, especially when hemoglobin, ferritin, and transferrin saturation are within normal ranges.
In some cases, a low sTfR may be seen when bone marrow activity is suppressed or slowed, such as during chronic illness, significant inflammation, kidney disease, or certain endocrine or nutritional deficiencies that affect red blood cell production. It may also occur after recent blood transfusion or in situations where erythropoiesis (new red blood cell formation) is temporarily reduced.
Importantly, a low sTfR does not typically indicate iron deficiency and is not usually a cause for concern on its own. Interpretation should always consider the broader clinical picture, including a complete blood count (CBC), ferritin, transferrin saturation (TSAT), inflammatory markers (such as CRP), and symptoms. When anemia is present alongside a low sTfR, further evaluation may be needed to explore non–iron-related causes.
In most cases, low sTfR values are clinically reassuring and suggest that iron supply is sufficient relative to the body’s current needs.
Laboratories
Bring All Your Lab Results Together — In One Place
We accept reports from any lab, so you can easily collect and organize all your health information in one secure spot.
Pricing Table
Gather Your Lab History — and Finally Make Sense of It
Finally, Your Lab Results Organized and Clear
Personal plans
$79/ year
Advanced Plan
Access your lab reports, explanations, and tracking tools.
- Import lab results from any provider
- Track all results with visual tools
- Customize your reference ranges
- Export your full lab history anytime
- Share results securely with anyone
- Receive 5 reports entered for you
- Cancel or upgrade anytime
$250/ once
Unlimited Account
Pay once, access everything—no monthly fees, no limits.
- Import lab results from any provider
- Track all results with visual tools
- Customize your reference ranges
- Export your full lab history anytime
- Share results securely with anyone
- Receive 10 reports entered for you
- No subscriptions. No extra fees.
$45/ month
Pro Monthly
Designed for professionals managing their clients' lab reports
- Import lab results from any provider
- Track lab results for multiple clients
- Customize reference ranges per client
- Export lab histories and reports
- Begin with first report entered by us
- Cancel or upgrade anytime
About membership
What's included in a Healthmatters membership
Import Lab Results from Any Source
See Your Health Timeline
Understand What Your Results Mean
Visualize Your Results
Data Entry Service for Your Reports
Securely Share With Anyone You Trust
Let Your Lab Results Tell the Full Story
Once your results are in one place, see the bigger picture — track trends over time, compare data side by side, export your full history, and share securely with anyone you trust.
Bring all your results together to compare, track progress, export your history, and share securely.
What Healthmatters Members Are Saying
Frequently asked questions
Healthmatters is a personal health dashboard that helps you organize and understand your lab results. It collects and displays your medical test data from any lab in one secure, easy-to-use platform.
- Individuals who want to track and understand their health over time.
- Health professionals, such as doctors, nutritionists, and wellness coaches, need to manage and interpret lab data for their clients.
With a Healthmatters account, you can:
- Upload lab reports from any lab
- View your data in interactive graphs, tables, and timelines
- Track trends and monitor changes over time
- Customize your reference ranges
- Export and share your full lab history
- Access your results anytime, from any device
Professionals can also analyze client data more efficiently and save time managing lab reports.
Healthmatters.io personal account provides in-depth research on 10000+ biomarkers, including information and suggestions for test panels such as, but not limited to:
- The GI Effects® Comprehensive Stool Profile,
- GI-MAP,
- The NutrEval FMV®,
- The ION Profile,
- Amino Acids Profile,
- Dried Urine Test for Comprehensive Hormones (DUTCH),
- Organic Acids Test,
- Organix Comprehensive Profile,
- Toxic Metals,
- Complete Blood Count (CBC),
- Metabolic panel,
- Thyroid panel,
- Lipid Panel,
- Urinalysis,
- And many, many more.
You can combine all test reports inside your Healthmatters account and keep them in one place. It gives you an excellent overview of all your health data. Once you retest, you can add new results and compare them.
If you are still determining whether Healthmatters support your lab results, the rule is that if you can test it, you can upload it to Healthmatters.
We implement proven measures to keep your data safe.
At HealthMatters, we're committed to maintaining the security and confidentiality of your personal information. We've put industry-leading security standards in place to help protect against the loss, misuse, or alteration of the information under our control. We use procedural, physical, and electronic security methods designed to prevent unauthorized people from getting access to this information. Our internal code of conduct adds additional privacy protection. All data is backed up multiple times a day and encrypted using SSL certificates. See our Privacy Policy for more details.