The Test Sample
What is being tested?
This test measures the amount of haemoglobin (a protein found in red blood cells) in your blood and is a good indication of your blood's ability to carry oxygen throughout your body. Haemoglobin carries oxygen to cells from the lungs. If your haemoglobin levels are low, you have anaemia, a condition in which your body is not getting enough oxygen, causing fatigue and weakness. If your haemoglobin levels are high, this usually means you have too many red cells which is called polycythaemia. Polycythaemia, when severe, can cause the blood to become too viscous (thick), potentially leading to heart failure, heart attacks or strokes.
How is the sample collected for testing?
A blood sample is collected by inserting a needle into a vein in your arm or by a finger-prick (for children and adults) or heel-prick (for newborns).
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
Ideally you should be reasonably hydrated when having a haemoglobin test or the result may be inaccurately high.