If you thought nutritional deficiencies in developed countries were a thing of the past, you might want to think again. According to the latest statistical data from the Centers for Disease Control and Prevention (CDC), iron deficiency is the most common nutritional deficiency in the United States. In fact, nearly nine percent of all women currently living in the U.S. are deficient in this key nutrient.

So what does all of this mean and why does it matter?

Iron plays a crucial role in the oxygenation process of red blood cells by helping with the production of hemoglobin, a protein needed for the transportation of fresh, oxygenated blood throughout the body. Without sufficient levels of iron in the blood, as seen in iron deficiency and iron deficiency anemia, the body’s cells slowly begin to “suffocate,” thus becoming less and less efficient.

So how can you tell if you’re suffering from an iron deficiency? If you’re plagued by the following four symptoms, you may want to see a doctor and ask them to run a special test to detect the levels of iron in your blood.

You're tired

While there are many reasons why you may be feeling tired (who can pinpoint just one reason?) a deficiency in iron is among the most likely of causes. If you struggle to get out of bed in the mornings, or if you can’t make it through an entire day without taking a nap, it may be time to have the iron levels in your blood checked - particularly if you’re also experiencing weakness and irritability, or if you’re having difficulty concentrating.

You're pale

Until now, I never thought much about the correlation between the words “pale” and “sickly.” But as it turns out, the connection between the two words isn’t all that peculiar. When your blood has inadequate levels of hemoglobin, which results directly from low levels of iron, color slowly disappears from your skin. As it turns out, hemoglobin is largely responsible for the healthy, pinkish hue of certain skin colors, as well as our gums, the inside of our mouths, and the inside of our eyelids.

You have heavy periods

As per Doctor Jacques Moritz, MD, the director of gynecology at Mount Sinai St. Luke's Roosevelt in New York City, the number one cause of iron deficiency in women of child-bearing age is heavy bleeding during menstruation. According to Dr. Moritz, some menstruating women, “…lose too much blood, replace about half of it, and then lose too much again the following month." If you find yourself changing your pad or tampon more often than every two hours, you may want to talk to your gynecologist about having your blood iron levels checked.

You have an irregular heartbeat

Surprisingly, several heart-related conditions, such as an irregular heartbeat, heart murmur or enlargement of the heart muscle, can be caused by consistently low levels of iron in the blood. In fact, being severely deficient in iron can even lead to heart failure. (Before you go into panic mode, heart failure from an iron deficiency is uncommon and most likely caused by iron deficiency anemia that has gone untreated for quite some time.) However, it’s important to have your blood iron levels checked If you have a heart issue or pre-existing condition, as its best to err on the side of caution when it comes to iron levels and your heart.