4) Anemia
Anemia comes with a wide range of symptoms. Mild anemia is usually asymptomatic, but the more severe the anemia is, the more pronounced the symptoms will be. They include easy fatiguability, intolerance to effort, awareness of heartbeats, shortness of breath and even loss of consciousness. Those symptoms occur because a decrease in the number of red blood cells decreases the capacity of blood to transport oxygen which leads to decreased energy production. Severe anemia can cause heart failure and death.