Unless you’re pregnant, recently gave birth, or have another major red flag, iron deficiency can take years to diagnose—if it gets diagnosed at all.

Why? Because screening practices vary wildly. What gets tested (and what doesn't) depends on where you are, who you see, and what they consider "necessary."

It wasn’t until 2020 that the World Health Organization (WHO) officially released guidelines on ferritin as a key indicator of iron status. Before that, the typical test performed was for serum iron, a test that fluctuates throughout the day and doesn’t reliably reflect iron stores. Even today, some doctors still rely on it.

And just this past year, in 2024, the US Preventive Services Task Force (USPSTF) declared there isn’t enough evidence to recommend routine iron screening for asymptomatic pregnant women.¹ They also say there’s no clear proof that treating iron deficiency anemia in pregnancy improves health outcomes.²  

~ Cue outrage on behalf of women’s health in the footnotes. ~

But let’s think for a moment—just because something isn’t classified as a medical emergency doesn’t mean it isn’t impacting your life. Fatigue, brain fog, hair loss, dizziness. These aren’t just minor inconveniences. They affect our energy, our work and productivity, and overall well-being.

So if standard screening isn’t enough, what should you actually test for? What do you need to ask for? And how often?

In this issue, I’m covering the essential iron tests every woman should get, what they actually measure, and how often you should check them to stay ahead of deficiency.

The Essential Iron Tests: How to Get a Full Picture of Your Iron Status

Iron isn’t just one number on a lab test. It’s a dynamic system.

If you’ve ever been told your iron levels are "normal" based on a single test, you may be missing critical information.

Many women develop symptoms of iron deficiency years before anemia shows up on standard blood work.

The Three Pillars of Iron Testing

Think of iron status as a three-part system:

Each test gives a different piece of the puzzle. Without looking at the full picture, it’s easy to miss early deficiency.

1️⃣ Storage: Do You Have Enough Iron in Reserve?

🩸 Ferritin: Your Iron Savings Account

Ferritin measures stored iron, acting as an early and the best indicator of deficiency, decreasing long before anemia develops.

Low ferritin signals iron depletion before anemia develops.

Many doctors only check hemoglobin. But you can have normal hemoglobin and still be iron deficient if ferritin is low.

✅ Typical reference range: 50–150 ng/mL³
⚠️ Deficiency starts below: 30 ng/mL
🚨 Severe deficiency: Below 15 ng/mL⁴

2️⃣ Transport: Is Iron Moving Through Your Blood Properly?

🩸 Serum Iron: The Cash in Your Wallet

Serum iron measures the iron currently in your blood, but because levels fluctuate throughout the day, it’s unreliable on its own.

Low serum iron doesn’t always indicate deficiency. It could mean poor absorption or simply temporary changes.

✅ Typical reference range for serum iron: 50–175 µg/dL

🩸 Total Iron Binding Capacity (TIBC) & Transferrin Saturation (TSAT, %): Your Credit Line & Spending Power

TIBC measures how much iron your blood could carry.

Transferrin saturation reflects how much iron is actually in circulation.

High TIBC with low transferrin saturation suggests your body is trying to grab more iron, but isn’t getting enough.

✅ Typical reference range for TSAT: 20–50%
⚠️ Deficiency starts below: Below 20%
🚨 Severe deficiency: Below 10%

3️⃣ Function: Is Iron Reaching Your Red Blood Cells?

🩸 Hemoglobin: Your Monthly Paycheck

Hemoglobin measures the iron actively in use for red blood cell production. If hemoglobin drops, you’re not bringing enough iron to meet your body’s needs.

Like a paycheck, it can look fine for a while, even when your savings (ferritin) are low, but eventually, if you don’t have enough reserves, your income won’t cover expenses.

Since hemoglobin only decreases after prolonged deficiency, it’s a late indicator of iron depletion.

✅ Typical reference range for hemoglobin: 12–15.5 g/dL
⚠️ Deficiency: Below 12 g/dL
🚨 Severe deficiency (anemia): Below 10 g/dL

Many routine blood tests check only hemoglobin because it’s the primary marker for diagnosing anemia. But you can be iron-deficient for months or even years before it falls.

If hemoglobin is all your doctor tests, you might not catch iron deficiency early enough.

Now that you have the full picture, what should you do at your next check-up?

1. Ask your doctor for a full iron panel, not just hemoglobin. Standard blood work often overlooks early iron deficiency, so advocate for a more complete test, including ferritin, transferrin saturation, and TIBC.

2. Be cautious of misleading "normal" lab ranges. Some labs classify ferritin as normal at just 10–15 ng/mL because it doesn’t meet the threshold for anemia. But at this level, you're already iron deficient.

3. Don’t stress over a single low serum iron result. Iron levels fluctuate throughout the day. Always interpret them alongside ferritin and transferrin saturation for a clearer picture.

Understanding your iron tests puts you in control. The more informed you are, the better decisions you can make for your health and daily energy.

If routine iron screening isn’t a priority in our healthcare system, we have to be our own advocates.

The reality is that getting the right answers often depends on knowing the right questions to ask.

And if you wait until deficiency is “bad enough” to show up on standard labs, you’ll already be deep in the trenches of fatigue, brain fog, and burnout.

🧪 To get an accurate picture of your iron status, don’t rely on a single test. Ask for ferritin, transferrin saturation, and TIBC to catch deficiency before it becomes a bigger problem.

💬 What’s been your experience with iron testing? Have you ever had to push for a full panel, or were you only given a basic test like hemoglobin? I’d love to know!

1  Interestingly, the USPSTF recommendation is based on a systematic review in which only one observational study examined the benefits of early detection and treatment of iron deficiency in pregnancy. That study found that treating iron deficiency lowered the odds of preeclampsia and preterm birth, while failing to treat it increased the risk of both. Does this highlight a lack of research in this area, or does it reflect the USPSTF’s threshold for what qualifies as “enough evidence” to warrant action on women’s health?

2  It’s also worth noting that if screening led to more diagnoses, it would obligate the healthcare system to treat, which adds costs (always a concern, of course). The fact that iron screening remains a gray area might suggest that these maternal and fetal risks aren’t considered “serious enough” to justify routine intervention.

3  Assuming no other conditions, like any active or chronic diseases characterized by inflammation.

4  Some labs still call this threshold “normal”. It typically depends on the standards adopted by the country or healthcare system.