Haemoglobin normal range: Hemoglobin is a protein in red

Hemoglobin is a protein in red blood cells that carries oxygen and carbon dioxide. Learn about normal hemoglobin levels by age and gender, causes and symptoms of low or high hemoglobin, and how to measure hemoglobin with a blood test. Normal hemoglobin values are related to the person's age and sex. Normal values may vary slightly between test systems, and which groups of doctors have determined "normal values" for their group of patients; however, the value ranges are close (vary by about 0.5 g/dl) for almost every group. Hemoglobin is a vital component of your blood. Learn why doctors test your hemoglobin levels during routine blood work and what abnormal results may mean. Learn what hemoglobin is, how it is tested, and what normal levels are for different age groups. Find out the causes and symptoms of low and high hemoglobin levels, and how to prevent and treat them.