How are Haemoglobin levels measured?
Haemoglobin absorbs light
- Haemoglobin which is high in O2 and Haemoglobin which is low in O2 will absorb different wave lengths of light. A pulse oximeter is used to measure haemoglobin in small capillaries. It can be placed on a finger, ear lobe or toe.
- Measurements should be taken when the patient is not moving, wearing nail varnish or has been diagnosed as Hypovolemic (decreased blood volume).
- People who have been exposed to carbon monoxide poisoning may give a false positive result.
- People with very cold hands from conditions such as Reynaud’s syndrome may give an inaccurately low reading.
