5 tell-tale physical signs of anemia, according to an expert, from paleness to weird cravings

• Anemia is the most common blood disorder.
• Changes to your skin, nails or appetite may indicate anemia related to low iron.

Anemia, the most common blood disorder, is a condition in which the body lacks enough healthy red blood cells in the blood to help distribute oxygen. Different types of anemia affect more than three million Americans, according to the American Society of Hematology.

One of the most common symptoms of anemia is fatigue, which makes it difficult for people to realize what they're experiencing is in fact anemia, according to Dr. Aaron Goodman, a hematologist and professor at UC San Diego Health.

"Some people can be asymptomatic. The most common complaint doctors see is fatigue, and a lot of things can cause fatigue," he told Insider. "It's very under diagnosed and when we give iron to patients with deficiency, they feel so much better. It's the easiest fix in the world."

Anemia is also easy to diagnose with a blood test.

Physical signs of anemia can vary based on the cause and severity. Changes to your skin or nails may be reason to get tested.

Abnormally pale skin is a common symptom of anemia

It's possible for a lack of red blood cells to show up on your skin, particularly with iron-deficiency anemia, the most common type.

Paleness may also be more pronounced in certain areas of the body like the conjunctiva, the lining of the eye.

However, anemia isn't the only explanation for abnormally pale skin. To rule out other potential culprits, look for other symptoms and consider a blood test.

"It's not usually super easy to spot unless you're a doctor and looking for it," Goodman said.

Anemia caused by iron deficiency may be related to menstruation, as a side effect of monthly blood loss, he said.

You may crave ice or dirt if you're anemic

If you find yourself raiding the ice machine for a snack, you may be anemic.

One of the more bizarre indicators of anemia is appetite changes, including a sudden desire to eat ice or even dirt.

It's not clear why it happens, according to Goodman.

"It sounds crazy but it's a real thing," he said.

Nails that are brittle or spoon-shaped can indicate iron deficiency, sometimes severe

Your hands and feet can also help reveal warning sign of anemia. A lack of iron can lead to a brittle texture or a concave dip in the middle of the nails, creating a spoon-shaped appearance known as koilonychia.

However, the phenomenon is relatively rare.

"It happens with severe forms of iron deficiency but that would be pretty unusual in the United States," Goodman said.

Sores around the mouth may be caused by vitamin deficiency

If you notice cracks or sores around your mouth, it may be related to one of several types of vitamin deficiency anemia, resulting from low levels of B12. Iron deficiency anemia can also cause mouth sores.

"It depends on the type of anemia. Those are usually in the advanced stages of anemia," Goodman said.

A swollen, red or smooth tongue is sometimes called anemia tongue

In more advanced stages of nutrient deficiency, people with anemia may develop a specific texture and appearance of the tongue related to the disorder.

"You can get a thickened, glossy tongue with certain forms. I can count on one hand how many times I've seen it, though," Goodman said.

The swelling may be accompanied by redness or soreness, too.