Believe it or not, the first thing your doctor assesses when you walk in the door is how you look physically — especially if he or she knows you well.

Altered appearance offers important clues to changes in health.

Your doctor is looking for changes in your skin color.

This is the first thing he or she will check when you walk in the door, even though you may not be aware of it.

If your skin becomes pale or ashen as you exercise, this can be a tip-off that your heart isn’t getting enough blood.

Likewise, if your nail beds (the skin around and under your fingernails and toenails) turn bluish, this can be due to low oxygen in red blood cells. This condition is called cyanosis.

Chronic cyanosis can be a sign of many different lung and breathing problems, as well as coronary artery disease.