Fatigue and Shortness of Breath in an Athlete Caused by Low Iron.

Athletes are used to performing at their best, so when they see their performance drop they start looking for causes. Christine* noticed she was unable to complete her normal exercise routine due to shortness of breath, and she went to her doctor to figure out why. Her doctor checked her heart and lungs - strong as ever - and then ran some routine blood tests.

Her complete blood count (CBC on lab report) showed her red blood cells (RBCs and hematocrit), and the molecule that carries oxygen in her blood (hemoglobin/Hb) had dropped, but she was still in the “normal range” - her doctor brushed it off saying no treatment was necessary. Except those blood results weren’t her normal range, they were 20% lower.

In the past, her athletic conditioning had increased the amount of oxygen-carrying RBCs and hemoglobin, the reason she used to endure so much exercise. Now with lower levels of these, her blood couldn’t carry as much oxygen, hence her early fatiguing and shortness of breath.

When weeks passed and Christine didn’t improve, her decreased performance became more and more frustrating. She went home and did a little bit of reading, and asked her doctor to follow up her initial testing with an iron study - a test that would look at her iron levels more in depth. Her iron stores (ferritin) were right on the border of the lower limit. Reluctantly her doctor agreed her iron stores “were on the low side” and recommeded she supplement iron - orally.

Christine wasn’t happy with this recommendation - first of all, she had a digestive condition which meant her absorption was already pretty low and oral iron can cause constipation - making this idea less appealing. On top of that, she was an athlete with a declining performance level, she didn’t want to have to wait months for her iron levels to (possibly) increase slowly, she wanted to feel better soon. She found out about IV iron, asked her doctor, and was told her health insurance would not cover that kind of treatment. Still frustrated, she found our clinic, Up and Up Natural Medicine in Carlsbad, where we perform IV iron infusions regularly to patients.

After talking with Christine about her medical history and reviewing her labs, it became clear that she was a good candidate for IV iron infusions. I explained to her IV iron infusions are generally given as a series of treatments, based on the level of hemoglobin and/or ferritin.

I always start patients on 100mg for their first treatment, and increase the dosage to 200mg per treatment afterwards. The procedure takes less than an hour, which includes taking vitals and monitoring the patient for 30 minutes afterwards to make sure their blood pressure does not drop (which is the most common side effect, though we haven’t seen it in our clinic). Patients usually feel improvement within 24hrs after their initial treatment, and continue to have improvements with further treatments. Most patients require between 300-1000mg total dosage, given over multiple treatments to replete their iron levels.

Patients can expect to initially see their hematocrit and hemoglobin increase in 24-72 hours, and their ferritin levels will stabilize after about 3 weeks after the end of their treatment. Our goal is to get their ferritin level over 100ng/mL and monitor periodically to ensure iron levels do not decline below an acceptable level (30-50mcg/L depending on conditions) over time.

* Patient’s name changed for privacy.

** Competing athletes may request to have this treatment to abide by World Anti-Doping Agency (WADA) standards (Letter requesting therapeutic use exemption of IV iron; less than 100mL IV administered in a 12 hour period)


Symptoms of Low Iron:

  • Excessive fatigue/tiredness
  • Weakness
  • Irritability
  • Shortness of breath (with exercise/exertion)
  • Chest pain, or rapid heart beat
  • Anemia - though not all anemias are due to iron-deficiency
  • Restless leg or limbs (made worse from low iron stores)
  • Paleness
  • Headaches, feeling dizzy, or light headed
  • Cold hands and feet
  • Brittle nails
  • Craving dirt, ice, or starch

Causes of Low Iron:

  • Insufficient iron in your diet. If you eat a diet low in iron, over time you will develop iron deficiency. Foods rich with iron include red meat, leafy green vegetables, eggs, lentils, and fortified foods.
  • Poor absorption of iron. Iron is absorbed from your small intestine, and conditions that affect it can lower the amount of iron that reaches your blood. Digestive conditions such as Celiac disease, inflammatory bowel disease (Crohn’s and ulcerative colitis), gastric bypass surgeries, small intestinal bacterial overgrowth (SIBO) can reduce your iron absorption. Also vitamin C helps us absorb iron, so if you’re not eating enough vitamin C at the same time as iron containing foods, you may decrease your absorption. Chronic use of antacids, or alkaline water may also affect your absorption of iron, since stomach acid is needed.
  • Blood loss. Since your red blood cells carry iron, any loss of them results in losing some iron. This can happen with stomach (peptic) ulcers, colon cancer, colon polyps, trauma, or excessive menstrual bleeding.
  • Pregnancy. A growing baby needs iron from their mother to make their own blood cells. In addition, Mom needs her own iron to increase her blood volume for her own oxygen consumption, and to supply her developing baby.  
  • Overtraining in athletes, especially females. Intensive exercise increases your demand on iron, and some sorts of high impact activities can break red blood cells or cause blood loss. Over time, this can result in iron deficiency.

Labs Associated with Low Iron:

  • CBC (complete blood count)
    • Low red blood cells (RBCs)
    • Low hematocrit (Hct)
    • Low hemoglobin (Hb) - below 12.0g
  • Iron Studies
    • Low ferritin (iron stores)
    • Low serum iron

Treatment of Low Iron:

  • Eating more iron containing foods. This approach works well in mild cases of iron deficiency, in people with good absorption. Eating foods high in vitamin C or taking supplemental vitamin C is also helpful.
  • Iron supplementation. This approach works well in patients with mild-moderate deficiency, and good absorption. Many forms can cause constipation, which can be balanced out by the vitamin C (which can soften stool). Iron bisglycinate with vitamin C is my preferred form with patients.
  • IV iron infusion. This is fastest way to correct a deficiency, and is suitable for moderate to severe severity. There are multiple forms of IV iron, we prefer to use iron sucrose (under the trade name Venofer) because it is the best tolerated and least likely to cause reactions when given intravenously.

People Who Should NOT Get IV Iron Infusions:

  • People who have:
  • Iron overload
  • Hemochromatosis
  • Normal ferritin >100ng/mL
  • History of allergy to injectable iron