Doctors weren't sure why a woman couldn't swallow until they looked at her nails

A middle-aged woman visited a hospital in Chicago, Illinois, in 2013 with complaints of exhaustion and shortness of breath.

When the hospital looked at her chart, they saw she had visited two years earlier with complaints of difficulty swallowing. A blood test found that she was severely anemic - a condition in which you either don't have enough red blood cells, or that they're so irregularly shaped that they can't hold on to a protein that ferries oxygen from the lungs to the rest of the body.

When they looked down her throat, they noticed thin ribbons of tissue protruding from her esophagus. These esophageal webs, as they're called, are why she struggled to swallow:

They also saw that her red blood cells were irregularly shaped (anisocytosis), unusually small, and paler than normal.

But what was the underlying condition causing these symptoms?

Turns out, the answer was in her nails, doctors reported in the December 2015 issue of the journal Clinical Case Reports.

People who are anemic often feel weak and tired, short of breath, or have headaches and dizziness because of the inefficient delivery of oxygen throughout the body. In the long run, untreated anemia can damage the heart and brain, and even cause death.

But there are several different kinds of anemia, each ranging in severity and frequency. And the type of treatment - and the decision to treat it at all - depends upon the kind of anemia you have.

After examining her hands, they noted that her nails appeared spoon-shaped (a condition called koilonychia) and flat (called platynychia).

These unique characteristics told doctors that she had chronic iron deficiency anemia - the most common form of anemia. It occurs when the body's stores of iron run low. Since iron is an important component of your red blood cells, they can't operate efficiently when reserves are drying up.

Doctors aren't sure how chronic iron deficiency causes flat, spoon-shaped nails, but the two conditions are usually associated with each other. Chronic iron deficiency also causes esophageal webs, which is why it was so hard for the patient to swallow.

In the end, the patient recovered after doctors treated her with iron replacement therapy. So if you ever find that you're having trouble swallowing and your nails have changed, see a doctor: Iron deficiency anemia may be to blame.