See Important Safety Information below.
You've been exhausted for a while. Not tired — exhausted. The kind where you wake up already behind, where climbing a flight of stairs requires a moment of recovery at the top, where the brain fog settles in so completely that you stop trusting your own thoughts. Your doctor says it's stress. Then perimenopause. Then "just life with kids." It isn't until someone orders blood work, including a complete blood count panel (CBC) and full iron panel, that anyone finds the actual answer: textbook iron deficiency anemia. And you've had it for years.
This story is far from rare. Studies show iron deficiency is common among women, especially during reproductive years. According to CDC data (Centers for Disease Control and Prevention) from the National Health and Nutrition Examination Survey¹ (NHANES), 22.6% of females aged 12 to 49 — nearly 1 in 4 — are iron deficient. And that's just the women who meet the formal cutoff.
Here's the part that's hard to accept: a NHANES-based study published in Journal of the American Medical Association (JAMA)² found that 83.6% of iron-deficient women did not yet have anemia. That means most of them would fly completely under the radar of standard anemia screening. They're suffering without a diagnosis because the wrong things are being tested, or nothing is being tested at all.
This guide is about why that happens, what the right tests look like, and how to stop accepting exhaustion as your baseline.
What iron deficiency anemia actually is (without the medical jargon)
One of iron’s key roles in the body is supporting the production of hemoglobin. Hemoglobin is the protein inside red blood cells that carries oxygen from your lungs to every tissue, muscle, and organ that needs it. When iron stores run low, hemoglobin production drops. When hemoglobin drops, your cells start running on less oxygen than they need. The result is a body that's struggling at a cellular level, and a person who feels like she's moving through water.
Iron deficiency doesn't happen all at once. First, your stored iron (measured by ferritin) depletes. At that stage, red blood cells can still function, but reserves are gone. If depletion continues, the body can no longer manufacture enough healthy red blood cells, and hemoglobin falls. That's when iron deficiency crosses into iron deficiency anemia, and that's typically when doctors start paying attention.
The problem is that the suffering starts long before the formal diagnosis. Low iron doesn't always mean anemia, and it can cause fatigue, hair loss, and brain fog³. Women at the iron deficiency stage (not yet anemic) are real patients with real symptoms who are regularly sent home with no answers.
Women are disproportionately affected for a reason: iron stores are drained by heavy periods, pregnancy, and breastfeeding. According to the 2024 National Center for Health Statistics Data Brief analyzing NHANES data from August 2021 through August 20234, anemia prevalence in females ages 12–19 was 17.4%, and 14.0% in women ages 20-59, compared to just 0.9% and 3.9% in males of the same age groups. This is not a coincidence. It is a design flaw in how women's health has historically been screened and treated.
Iron deficiency anemia symptoms (the ones you've been ignoring)
Exhaustion
The exhaustion is the thing everyone mentions first, and for good reason. This isn't "I need coffee" tired. It's the kind that makes you cancel plans you were actually looking forward to, that makes you wonder whether something is fundamentally wrong with you as a person, when in reality, something is measurably wrong with your blood.
When the body doesn't have enough iron, it can't produce enough hemoglobin to deliver oxygen to tissues. Without enough oxygen, muscles and organs work harder, which drains energy faster, and this symptom can sneak up gradually.
Beyond fatigue, classic symptoms of iron deficiency anemia include weakness, shortness of breath, dizziness, and heart palpitations. And then there are the stranger ones that make sense once you understand how IDA works:
Ice cravings (pagophagia)
Ice cravings are one form of pica. A symptom associated with iron deficiency where people may crave non-food items or substances not typically eaten. If you're going through trays of ice and can't explain why, get your iron tested.
Restless legs
The uncomfortable urge to move your legs at night, especially when trying to sleep, has a well-documented connection to low iron levels.
Brittle or spoon-shaped nails
Nails that curve upward at the edges (called koilonychia) are a classic physical sign of iron deficiency anemia.
Hair loss
Iron helps support hair follicle cell turnover and oxygen flow to the scalp. When the body is low on iron, it prioritizes essential functions (like keeping the heart beating) over less critical ones like growing hair, putting follicles into a resting phase, and leading to increased shedding and slower regrowth.
Pale skin and cold extremities
The drop in hemoglobin reduces the reddish hue in blood, which can show up as pallor in the face, gums, inside of the eyelids, and nail beds.
The reason so many women miss these symptoms, or miss connecting them, is that they develop slowly. When they creep in over months or years, you recalibrate your baseline. You forget what it felt like to have energy. And every time you mention fatigue, brain fog, or feeling off, you're told it's stress. It's being a mom. It's getting older. It's normal.
No, it's not normal, and it can be treated.
Why so many women go undiagnosed
The diagnostic gap here is not subtle. Among women who were iron-deficient in the JAMA NHANES study5, 83.6% did not have concurrent iron deficiency anemia, meaning they had low iron stores but hadn't yet crossed the hemoglobin threshold that triggers a formal diagnosis. Standard screening checks hemoglobin. If it's in range, you're told you're fine. But fine hemoglobin doesn't mean fine ferritin. And low ferritin causes real, significant symptoms.
Ferritin is the key marker for iron stores, and it is frequently not tested. When it is tested, "low-normal" is considered acceptable — even when the person in the exam room is exhausted, losing hair, and running on empty. Labs define normal ferritin ranges broadly, and a ferritin of 14 ng/mL technically clears the deficiency threshold while still leaving someone symptomatic.
There's also the dismissal factor. Women's symptoms are routinely minimized in healthcare settings. Fatigue is attributed to lifestyle. Cognitive fog gets chalked up to anxiety. Hair loss becomes a cosmetic concern rather than a clinical one. The result is women who spend years cycling through appointments without anyone ordering the right test or taking the results seriously when they do.
The disparities here are real and need to be said directly. According to the 2024 NCHS Data Brief6, the prevalence of anemia among Black women was 31.4%, compared to 15.9% in Asian women, 15.0% in Hispanic women, and 8.3% in White women. Anemia prevalence also decreases with increasing income, with women at the highest poverty level showing more than double the anemia prevalence of those at the lowest. These numbers are not incidental. They reflect systemic failures in who gets tested, who gets believed, and who gets treated.
Iron deficiency anemia labs (what to actually ask for)
"Checking iron" is not a single test, and a basic blood panel is almost certainly not enough. Here's what a complete iron workup looks like:
Complete blood count (CBC): Measures hemoglobin, hematocrit, mean corpuscular volume (MCV), and related markers. A low MCV indicates small red blood cells, which is commonly seen in iron deficiency anemia.
Serum ferritin: Measures stored iron. This is the most important number for catching deficiency before it becomes anemia. A ferritin below 15 ng/mL is technically deficient, but some studies suggest symptoms can appear at levels below 50 ng/mL.
Serum iron and Total Iron-Binding Capacity (TIBC): Together, these help calculate transferrin saturation, how much of the blood's iron-transport capacity is being used. A transferrin saturation below 20% suggests iron deficiency.
The key interpretation note: "everything's in range" is not a satisfying answer when you're functioning at 60%. Ask for the actual numbers, and ask specifically about ferritin. Many women have been told their iron levels were normal, only to discover their ferritin was critically depleted, and that once iron stores were actually addressed, the shift in energy, recovery, and mental clarity was dramatic7.
If additional factors may be affecting iron absorption — celiac disease, H. pylori, Crohn's disease, long-term proton pump inhibitors (PPI) use — those should be investigated alongside the iron panel. Some tests require fasting, and iron supplements should be held before testing so results aren't artificially skewed.
What causes iron deficiency anemia (and why it keeps coming back)
You are not iron-deficient because you're not trying hard enough. Here's what's actually behind it.
Heavy periods
This is the number one cause in premenopausal women, and it's frequently underdiagnosed in its own right. A typical period leads to a loss of around 16-32 milligrams of iron, but with heavy bleeding8, that number can rise to 80 milligrams or more, making it very difficult to replace iron through food alone. Heavy bleeding is generally defined as soaking through a pad or tampon hourly, passing large clots, or bleeding for more than seven to eight days. If that's the monthly experience and no one is treating the underlying cause, iron will keep bottoming out. Endometriosis, fibroids, adenomyosis, and PCOS can all drive heavy periods, and all carry an elevated risk of iron deficiency as a result.
Pregnancy and breastfeeding
The iron demands of growing a baby are significant. The body is manufacturing blood for two, and if stores weren't replete before conception, the deficit compounds quickly9.
Dietary insufficiency and absorption issues
Plant-based diets, restrictive eating, and food insecurity all limit dietary iron intake. Absorption is further affected by celiac disease, Crohn's, gastric bypass surgery, and chronic use of antacids or PPIs.
Hidden blood loss
GI bleeding from ulcers, polyps, or, rarely but importantly, colon cancer can cause iron deficiency without any obvious symptoms. If there's no clear gynecologic cause, GI evaluation is important.
Finding the root cause matters because treating the deficiency without addressing the source means it will come back. Supplementing iron while still losing it through untreated heavy periods or unaddressed malabsorption is like filling the bathtub with the drain open.
Iron deficiency anemia treatment (what actually works)
The first thing to understand is that diet alone rarely corrects true iron deficiency. Eating iron-rich foods — red meat, dark leafy greens, legumes, fortified cereals — matters for maintenance and prevention, and pairing those foods with vitamin C genuinely improves absorption. But when stores are depleted, and symptoms are significant, food is not going to move the needle fast enough.
Oral iron supplements
Oral iron supplements are the standard first-line treatment. Options include ferrous sulfate, ferrous gluconate, ferrous fumarate, and iron bisglycinate. They work, but the side effects are real. Constipation, nausea, stomach pain, and dark stools are common enough that many people stop taking them before iron stores are adequately replenished. If one formulation is intolerable, another may be better absorbed or gentler on digestion. Avoid taking iron alongside calcium, coffee, or tea, which all inhibit absorption.
IV iron infusion
Infusion is an option when oral iron fails, isn't tolerated, or isn't appropriate, and it's more accessible than many women realize. IV iron bypasses the GI system entirely, delivers iron directly into the bloodstream, and typically works faster than oral supplementation.
Monoferric (ferric derisomaltose) is FDA approved to replace up to 1000 mg of iron in a single, rapid infusion. Monoferric is used for treating iron deficiency anemia (IDA) when you have previously tried oral iron medications and they have not worked. Monoferric is an intravenous iron treatment, meaning it is administered through your vein from a drip. Monoferric is also used for treating IDA if you have chronic kidney disease but are not dependent on hemodialysis. The dose may be repeated if IDA reoccurs. The intravenous infusion may take 20 minutes or more. Like all IV iron treatments, Monoferric has risks your doctor will discuss with you. Monoferric is contraindicated in patients with a history of serious hypersensitivity to ferric derisomaltose or any of its components, including reactions such as anaphylaxis, shock, hypotension, loss of consciousness, or collapse. Infusions are administered in a monitored clinical setting for this reason. See full prescribing information and Important Safety Information at the end of this article.
Stop accepting exhaustion as your baseline
If something feels wrong, it probably is. Researchers from the University of Michigan have noted that iron deficiency symptoms, and even those of anemia, are normalized in young females10, raising the question of why we aren't screening for a highly prevalent condition, easily diagnosed, and easily treated.
When talking to a doctor, be specific. "I need a complete iron panel including ferritin" is more useful than "Can you check my iron?" Track symptoms: fatigue levels, period heaviness, and how energy shifts week over week. Bring that data to the appointment. If concerns are dismissed without the full panel being ordered, consider seeking a second opinion.
The relief of finally having an answer is real. So is the difference between a body running on depleted stores and one that actually has what it needs. Nearly 1 in 4 women of reproductive age are iron-deficient. You don't have to be one of them without knowing it.
What is Monoferric?
Monoferric (ferric derisomaltose) is a prescription iron treatment given through a vein (IV) to treat iron deficiency anemia in adults who:
cannot tolerate oral iron or who have not responded well to treatment with oral iron
have non-dialysis dependent chronic kidney disease
IMPORTANT SAFETY INFORMATION
Who should not receive Monoferric?
Do not receive Monoferric if you have had serious allergic reactions to ferric derisomaltose or any of its ingredients.
What are the possible side effects of Monoferric?
Monoferric may cause serious side effects, including:
Allergic (hypersensitivity) reactions. Serious life-threatening allergic reactions have happened in people who receive Monoferric. Symptoms of an allergic reaction including rash, itching, hives, dizziness, lightheadedness, breathing problems, and low blood pressure have also happened during treatment with Monoferric. Tell your healthcare provider right away if you develop any of the above symptoms of a serious allergic reaction or if you have ever had any unusual or allergic reaction to any IV iron in the past.
Too much iron stored in your body (iron overload). Your healthcare provider should check the iron level in your blood before you start and during treatment with Monoferric.
The most common side effects of Monoferric include rash and nausea.
These are not all the possible side effects of Monoferric. Call your doctor for medical advice about side effects.
What should I tell my doctor or healthcare provider before receiving Monoferric?
Before receiving Monoferric, tell your healthcare provider about all your medical conditions, including if you:
have had an allergic reaction to IV iron.
are pregnant or plan to become pregnant. It is not known if Monoferric will harm your unborn baby. Untreated iron deficiency anemia during pregnancy may increase risks for you and your baby.
are breastfeeding or plan to breastfeed. Data from women treated with Monoferric show that iron is present in breast milk. It is not known how Monoferric may affect your breastfed baby.
Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.
You are encouraged to report negative side effects to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.
Please see full Prescribing Information including information for patients.
US-FDI-2600014 V2 07/26
References
Anemia Prevalence: United States, August 2021–August 2023 - NCHS Data Briefs - NCBI Bookshelf
Fixing My Low Iron Levels Changed My Life — Here’s Why - Rescripted
Why Is Iron Important While TTC and During Pregnancy? - Rescripted
Over 38% of Young Women Iron Deficient, New Research Finds - Women's Healthcare