A condition known as postural orthostatic tachycardia syndrome, or PoTS, causes an increase of at least 30 beats per minute after standing, according to Patient.co.uk. Standing up quickly and eating refined foods, such as white sugar and flour, can worsen PoTS.
People who have PoTS often experience symptoms such as dizziness, shakiness and purplish discoloration of the skin due to blood pooling, according to Patient.co.uk. Other symptoms include sweating, chest pain and bladder problems. PoTS occurs because the body must adjust to standing by contracting blood vessel's and increasing the heart rate to maintain blood supply to the brain and heart. This process does not work correctly in people with PoTS. Instead the heart beats excessively fast, there is altered blood flow to the brain, and levels of epinephrine in the body increase. Compression stockings, adequate fluid intake and a diet higher in salt may help.
There are many other possible causes of heart palpitations, according to WebMD. A fast heart rate may occur due to low blood sugar, low blood pressure or dehydration, but often the cause is nonmedical in nature. Caffeine, nicotine and hormonal changes can cause a fast heart rate. Strong emotions, such as stress and fear, can trigger panic attacks in some people, who experience increased heart rate. Pregnancy, an imbalance in electrolytes and herbal supplements are also common causes.