Blood WorkAnemia is found with a complete blood count (CBC), which measures your hemoglobin and the size of your red blood cells. Iron deficiency, the most common cause, is found with ferritin, which shows your iron stores and often falls months before anemia appears. At Passion Health, the $119 Energy & Iron Panel checks both, plus iron, B12, folate and thyroid; a blood count and ferritin alone come to $64.
What to know about anemia and iron deficiency
Anemia means your blood has too little hemoglobin, the protein in red blood cells that carries oxygen. It can make you tired, short of breath with activity, pale, dizzy or cold, and some people crave ice. Mild anemia often causes no symptoms at all.
Iron deficiency is the most common cause, and it develops in stages: your iron stores (ferritin) run down first, then your red blood cells get smaller, and only then does hemoglobin fall. So you can be low in iron, and feel it, before a blood count shows anemia. Other causes include low vitamin B12 or folate, kidney disease, long-term inflammation, blood loss and inherited conditions such as thalassemia trait.
Who should get tested?
- Tiredness, shortness of breath or a racing heart with everyday activity.
- Heavy or long periods, pregnancy or a recent pregnancy.
- A vegetarian or vegan diet, or frequent blood donation.
- Weight-loss surgery, celiac disease or inflammatory bowel disease, which reduce absorption.
- Hair shedding or restless legs, where ferritin is often checked.
- Long-term acid-reducing medicine or metformin, which can lower B12.
Which tests check for anemia and low iron?
| Test | What it shows | Where it's included |
|---|---|---|
| Complete blood count (CBC) | Hemoglobin and hematocrit show anemia. MCV shows red cell size: small cells point to iron deficiency, large cells to B12 or folate deficiency. RDW shows mixed sizes. | Essential $59, Energy & Iron $119, Full Blood Work $149, Men's and Women's panels. Alone $20. |
| Ferritin | Your iron stores, the first thing to fall. Read the ferritin guide. | Energy & Iron $119. Alone $15. |
| Iron, binding capacity, transferrin saturation | Iron in your blood right now. Helps when ferritin is borderline or raised by inflammation. | Energy & Iron $119. Alone $20. |
| Vitamin B12 and folate | The other common nutritional causes of anemia. Vitamin deficiency guide. | Energy & Iron $119. B12 $30, folate $20. |
| TSH | Rules out an underactive thyroid, another common cause of tiredness. | Energy & Iron $119. Alone $20. |
If your results point to an inherited cause or your clinician needs more detail, tests such as a reticulocyte count or hemoglobin electrophoresis are ordered separately.
What your results mean
| Result | What it suggests |
|---|---|
| Hemoglobin below 13 g/dL in men, or 12 g/dL in women who aren't pregnant | Anemia, using the World Health Organization cutoffs. Your lab's range may differ slightly. |
| Ferritin below 15 ng/mL | Iron stores are essentially empty: iron deficiency. |
| Ferritin below 45 ng/mL with anemia | Iron deficiency is the likely cause (American Gastroenterological Association cutoff). |
| Normal or high ferritin with transferrin saturation below 20% | Iron deficiency can still be present when inflammation, infection or liver disease raises ferritin. |
| Large red cells (high MCV) | Points to low B12 or folate, alcohol, thyroid or liver causes. |
A clinician reads these together. One result rarely tells the whole story, and the cause matters as much as the number.
What these tests can't tell you
Blood tests show that you're low in iron, not why. In men and in women after menopause, iron deficiency anemia often comes from slow blood loss in the gut, so the American Gastroenterological Association recommends an upper endoscopy and a colonoscopy for most of them. In women who still have periods, heavy bleeding is the usual cause, though other causes are still considered. A blood count also can't confirm thalassemia trait on its own.
If your results are off at Passion Health
A Texas-licensed clinician reviews every result and calls you the same day about anything critical. If you're anemic or low in iron, we:
- look for the cause, such as periods, diet, absorption, medicines or bleeding, and refer you for a gut evaluation when guidelines call for it;
- start iron, usually as tablets, or B12 or folate when those are low;
- recheck your blood count and ferritin in about 8 to 12 weeks;
- refer you for IV iron or to a specialist if tablets don't work or you can't take them.
Go over your results in a 20-minute video visit ($60), or get care online for restless legs or brain fog.
Anemia and iron test cost in Texas
Self-pay. The Energy & Iron Panel is $119 (34 results): blood count, ferritin, iron studies, B12, folate, thyroid and the metabolic panel, with the draw and a clinician's review. Bought separately, those tests come to $174. A blood count and ferritin alone come to $64 ($20, $15 and the $29 draw and review fee). Essential Blood Work ($59) has a blood count but not ferritin; add ferritin for $15 with no extra fee.
With insurance. If we're in network with your plan, we bill it when the test is covered. You pay cash for a test only after we tell you the price in writing, and Medicare patients sign an Advance Beneficiary Notice first.
Anemia and iron deficiency test questions
What blood test shows anemia?
A complete blood count (CBC). Hemoglobin below 13 g/dL in men or 12 g/dL in women who aren't pregnant means anemia, and the size of your red cells (MCV) hints at the cause.
What is the best test for iron deficiency?
Ferritin, which measures your iron stores. It falls first, often before anemia shows up. When inflammation may be raising ferritin, transferrin saturation helps.
Can you have low iron without anemia?
Yes. Iron stores run down before hemoglobin falls, so you can have low ferritin, and symptoms like tiredness, hair shedding or restless legs, with a normal blood count.
What ferritin level is too low?
Below 15 ng/mL means iron stores are essentially empty. With anemia, below 45 ng/mL usually means iron deficiency is the cause. Your clinician reads ferritin with your blood count and any inflammation.
Do I need to fast for an anemia test?
A blood count, ferritin and iron tests don't need fasting; skip iron pills the morning of your draw. The Energy & Iron Panel includes a metabolic panel, so fast 8 to 12 hours before that draw; water is fine.
How long does it take to fix iron deficiency?
Hemoglobin usually starts rising within a few weeks of taking iron, but refilling your iron stores takes about three months of treatment. We recheck your blood count and ferritin to make sure it's working.
Sources
- World Health Organization: Guideline on haemoglobin cutoffs to define anaemia in individuals and populations, 2024
- AGA Clinical Practice Guidelines on the Gastrointestinal Evaluation of Iron Deficiency Anemia, Gastroenterology, 2020
- NIH Office of Dietary Supplements: Iron, Health Professional Fact Sheet
- NIH Office of Dietary Supplements: Vitamin B12, Health Professional Fact Sheet