This is the single most important test for diagnosing anemia and understanding your energy levels. The Hemoglobin (Hb) test precisely measures the amount of the oxygen-carrying protein in your red blood cells. Low hemoglobin is the hallmark of anemia, which causes fatigue, weakness, and shortness of breath. This test is the definitive starting point for investigation. It's a core part of our Complete Blood Count (CBC), but can be ordered individually. A simple blood draw provides this non-negotiable number for your health. Find out if low iron or another issue is holding you back.