What is blood?
Blood is the composite of a number of ingredients:
- Red blood cells
- White blood cells
- Blood proteins
- Nutrients, hormones, electrolytes
The Function of Blood
Our blood is the “river of the body.” It runs between all of our cells delivering nutrients to them and taking toxins away.
We have about 5 litres of blood which accounts for 8 percent of our body weight.
There is a complex system our body uses to control where the blood goes at any given moment. For example, if you go to the gym and exercise your bicep, the blood flow to that muscle will increase in order to supply it with the resources it needs to perform (oxygen, glucose, minerals, etc.).
Blood Is Dynamic and Tests Are a Snapshot
Blood tests are used regularly as a diagnostic tool. Often the results are useful in determining a diagnosis but many times they are useless. For example, if a doctor suspects iron-deficiency anemia, a simple blood test will reveal iron status.
For certain conditions however, blood tests fall short as a diagnostic tool. Cancer can be growing for 20-30 years without seeing any changes in the blood. Joint degeneration might be debilitating an individual, yet there would be no markers in the blood for this process.
Average Versus Optimal
One of the problems with relying on blood tests as a measure of health is that reference ranges are based on the average population. These reference ranges are established so that diseases and conditions can be identified, not prevented. There is however levels that can be observed that in fact identify imbalances before they become problems.
For example, if you go and get your vitamin D levels checked, the doctor will only call you back if your result falls out of their reference range of 75-225 nmol/L. However, the optimal range which has been proven to be much more accurate for the prevention of disease is between 125-200 nmol/L. 1 2 3 4
Reasons To Get Tested
- Genetic variances
- Nutrient deficiencies
- Different body types
- Underlying disease state
- Drug use
- Assess risk of death and/or disease
Blood Test Guidelines
- Always ask for a copy of the results. It is essential that you compare your blood test results to optimal levels, not average.
- Keep all copy in a safe place. You never know when you might need to reference a past test. This could be very valuable information for a practitioner.
- Ask your doctor what the test means. You are responsible for you. Make sure you understand your body the best you can.
- Prepare your questions before the appointment. Planning ahead will prevent you from forgetting to ask the important questions. In addition, your doctor will understand that you are serious about your health and will thus respond appropriately.
- Offer to pay for any tests not covered. No test should ever be denied if you have a valid justification for getting the test. If you must pay for it, then do so. We sometimes forget (in Canada) that this is an option.
Remember, health care practitioners (doctors, surgeons, naturopaths, nutritionists, etc.) are here to serve you. You should never feel apprehensive about asking them questions about your health.
Blood tests can be extremely valuable diagnostic tools if used the right way.
Take control of your health!
- Von Hurst PR, Stonehouse W, Coad J.Vitamin D supplementation reduces insulin resistance in South Asian women living in New Zealand who are insulin resistant and vitamin D deficient – a randomised, placebo-controlled trial. Br J Nutr. 2010 Feb;103:549-55. ↩
- Stewart B. Leavitt, MA, PhD, Pain Treatment Topics, June 2008. ↩
- Ward et al. Vitamin D Status and Muscle Function in Post-Menarchal Adolescent Girls. JCEM. 2009 Feb;94:559. ↩
- Gine et al. Association Between Serum 25-Hydroxyvitamin D Level and Upper Respiratory Tract Infection in the Third National Health and Nutrition Examination Survey. Arch Intern Med. 2009;169:384-390. ↩