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Blood Testing - why?

Most people don’t do any blood tests until they get ill and are forced to go through a health checkup, or are already diagnosed with metabolic syndrome, cardiovascular disease or diabetes etc. This is unfortunate, because regular blood testing is the single best strategy to stay healthy thought life. In this article I will explain why you want to get your blood tests and which ones to get.

Blood testing – What for? When?

The main reason to start doing regular blood testing at a young age when you are at your peak it to establish your individual healthy baseline. Reference ranges that are printed in lab result reports are just that – a reference. The range of values in the reference range – aka the “normal range” – only shows the distribution of values in a population, not what is optimal for a particular individual. Also, normal ranges are often very wide. For ex. for total testosterone, the male normal range spans all the way from around 300 to 1,200 ng/dL.[1] The female range is smaller, 10-60 ng/dL [2], but low vs high testosterone levels within this range can still have significant implications for women. (Note that for testosterone, the normal ranges vary vastly between different laboratories and assays). Other parameters with wide normal ranges are DHEA, TSH (thyroid-stimulating hormone) and the gonadotrophins (LH and FSH).
For men, it is especially important to check their testosterone levels at a young age, because of its wide normal range. Due to differences in androgen receptor sensitivity, among men having the same testosterone level, some can be suffering hypogonadal symptoms and metabolic disturbances while others are perfectly fine.[3-6] This is the great dilemma in diagnosing testosterone deficiency (aka hypogonadism or Low-T). If you know what your testosterone level was when you were young, you can track the decline and see how much it has fallen over the years. This will provide invaluable information for you and your doctor when it comes to dosing testosterone replacement therapy, if you were to end up with testosterone deficiency.
For women, it is especially important to monitor thyroid levels, as hypothyroidism – both overt and subclinical - is more common in women than men [7, 8] and may contribute to women’s propensity to gain body fat more easily than men.[9-13] The prevalence of overt and subclinical hypothyroidism is 5% and up to 20%, respectively.[8, 14] Checking the thyroid is critical for women who desire pregnancy, as both overt and sub-clinical hypothyroidism can have an adverse impact on fetal development and cause miscarriage.[15] Another female issue, hypoactive sexual desire disorder, can be – at least partly – caused by low testosterone levels.[16] Low testosterone also has other detrimental effects in women (for more on that see my previous article “Testosterone in women - is it physiological and clinically important?”. [17] Thus, it is equally important for women to check their testosterone levels as it is for men to check their estrogen levels.
Thus, the only way to find out what is optimal for you as an individual is to do blood testing when you are young and healthy. This will be invaluable when you get 20+ years older and start to experience health issues, as it will show you what parameters are off, and give clues to what went wrong and what treatment will be best for you. A fool proof investment in your health!
If you read this and are already in your middle-age, ask yourself how long ago did you last have your blood test done? Even though you have passed your peak, it is never too late to find out your health status. And the sooner you do, the greater the likelihood you may detect and do something about it before it’s too late.

What labs to get?

What follows is list of panels you want to get checked on a regular basis as part of your health screening.
Comprehensive metabolic panel (CMP)
A comprehensive metabolic panel (aka chemistry panel) is a group of blood tests that gives information about: [18, 19]
- How your kidneys and liver are working
- Blood sugar (aka blood glucose) and calcium levels
- Sodium, potassium, and chloride levels (called electrolytes)
- Protein levels
The CMP includes the following tests:
Glucose - energy source for the body; a steady supply must be available for use, and a relatively constant level of glucose must be maintained in the blood.
Albumin - a small protein produced in the liver that is the major protein in the blood
Total Protein - measures albumin as well as all other proteins in the blood
Sodium - vital to normal body processes, including nerve and muscle function
Potassium - vital to cell metabolism and muscle function
Calcium - one of the most important minerals in the body; it is essential for the proper functioning of muscles, nerves, and the heart and is required in blood clotting and in the formation of bones.
Chloride - helps to regulate the amount of fluid in the body and maintain the acid-base balance
CO2 (carbon dioxide, bicarbonate) - helps to maintain the body's acid-base balance (pH)
Kidney Tests
BUN (blood urea nitrogen) - waste product filtered out of the blood by the kidneys; conditions that affect the kidney have the potential to affect the amount of urea in the blood.
Creatinine - waste product produced in the muscles; it is filtered out of the blood by the kidneys so blood levels are a good indication of how well the kidneys are working.
Liver Tests
ALP (alkaline phosphatase) - enzyme found in the liver and other tissues, bone; elevated levels of ALP in the blood are most commonly caused by liver disease or bone disorders.
ALT (alanine amino transferase, also called SGPT) - enzyme found mostly in the cells of the liver and kidney; a useful test for detecting liver damage
AST (aspartate amino transferase, also called SGOT) - enzyme found especially in cells in the heart and liver; also a useful test for detecting liver damage
GGT (see my previous article for more info)
Bilirubin - waste product produced by the liver as it breaks down and recycles aged red blood cells
Complete blood count (CBC)
A complete blood count test measures the following:
The number of red blood cells (RBC count)
The number of white blood cells (WBC count)
The total amount of hemoglobin in the blood
The fraction of the blood composed of red blood cells (hematocrit)
Average red blood cell size (MCV)
Hemoglobin amount per red blood cell (MCH)
The amount of hemoglobin relative to the size of the cell (hemoglobin concentration) per red blood cell (MCHC)
Platelet count 
The CMP and CMC are the most commonly ordered blood test panels by doctors, as they give a good snapshot of your overall health. During acute illness, CMP and CMC are the most valuable tests. However, they do not provide enough information for you if your goal is health promotion and not just mere survival. For health promotion, you also want to check the following.
HbA1c - glycated hemoglobin - an indicator of average blood glucose levels over past 3 months).
Uric acid and eGFR (estimated glomerular filtration rate) are two additional good parameters of kidney function, especially uric acid (which I will cover in more depth in an upcoming article).
When it comes to liver function, you also want to check GGT (gamma-glutamyl transpeptidase), as it help you distinguish exercise-induced elevations in transaminases from those caused by liver disease. For more on this, see my previous article “Got Elevated Liver Enzymes? - Here's How To Interpret Your Liver Function Tests

Lipid Profile

The standard lipid profile give you the following:
Total cholesterol
HDL cholesterol
LDL cholesterol 
VLDL cholesterol 
From this, you can easily calculate your non-HDL and remnant cholesterol. For more info on that, see my previous article “Remnant Cholesterol and non-HDL – What’s that? Why bother?” 
This is a good start. If your non-HDL and remnant cholesterol levels are fine, you don’t need to have an advanced lipid panel done. However, if your triglycerides are high and HDL low, you likely have atherogenic dyslipidemia and have to keep an eye on your “bad cholesterol” particles. For that, you need an advanced lipid panel. For more info, check out:
Inflammatory status
C-Reactive Protein (CRP) is a good indicator of overall inflammatory status in the body, which is has implications for health promotion and something you want to monitor.
Hormones and Gonadotrophins
Both men and women should monitor their hormone levels and gonadotrophins (LH and FSH).
Testosterone, total and free
Estradiol, total and free
T4, total and free
T3, total and free
Men should also check their PSA (prostate specific antigen) and DHT (dihydro-testosterone) levels.
Nutrition status 
Have you ever wondered if you’re getting enough nutrients to cover your needs and if supplements are necessary? The nutrition panel will objectively answer that question for you. Everybody has different nutrient requirements due to different lifestyles (eg. strenuous exercise training vs. sedentary vs. diseased etc.) and genetics. Also, for health promotion you may want to keep your nutrient levels a bit higher than necessary for mere survival. By getting the following nutrition labs you will know exactly what you’re missing and if you need supplements:
Vitamin A
Vitamin B1 (thiamine)
Vitamin B2 (riboflavin)
Vitamin B3 (niacin)
Vitamin B6
Vitamin B12
Folate (aka vitamin B9 or folacin)
Homocysteine (a breakdown product of protein metabolism, whose levels are affected by vitamin B6, B12 and folate)
Vitamin C
Vitamin D 25-hydroxy
Ferritin (a marker of total iron stores in the body that better reflects iron status than iron levels in blood)
Magnesium RBC (red blood cell)
The labs listed above give you the individualized information you need to safeguard your health. There is a lot to say about some of them, which I will cover in upcoming articles.

How often?

For young adults in their 20s, doing blood testing every 3-4 years is a good guideline. After 35 years of age, once per year is recommended. Of course, is things are out of whack and you start taking any type of medication, more frequent blood testing will be needed.

Fasting or not?

Most doctors routinely request fasting blood samples. However, recent research shows that this is not required in most cases. For example, the European Atherosclerosis Society has officially stated that fasting is not routinely required for cholesterol (lipid) testing.[20] Also, after-meal (postprandial) blood glucose is a stronger risk factor for both cardiovascular disease and diabetes than fasting glucose levels.[21-23] When it comes to testosterone levels in men, to get the most accurate reading you should do the blood draw fasting. See my previous article “Testing for testosterone deficiency - things to know about the blood draw” for more on that.

Where to get your blood test order (requisition)?

There are two options:
Alternative 1:
Get a primary care doctor (if you don’t already have one) and tell that you want to do comprehensive blood testing (you can print out this article and give your doc the list above). However, be prepared that you doc will say that all of these labs are not “necessary”. Just reply “they may not be necessary for you, but they are necessary for me”. Some or all of the labs you can put on your health insurance.
Alternative 2:
Order your blood tests online. If you order your blood tests online you don’t need a doctor and it won’t be covered by any health insurance. One of the best online blood test providers is Life Extension. If you order via Life Extension, they will mail you the lab requisition; a document that you bring to LabCorp, where you do the blood draw. Life Extension offers a large menu of blood test:
This panel contains many of the labs listed above:
For hormones, Life Extension has separate packages for men and women. When ordering lab tests online it is important to remember the packages offered (and their names) are not standardized, and different packages may contain one or several of the labs you will find in other packages. To get everything, you may have to order a few packages as well as individual test that are sold separately (most of what you find in the packages you can also buy separately).

Bottom line

Here you got the info you need to make the best ever foolproof investment in your health! When it comes to nutrients, it strikes me how common it is for people to take a bunch of suppslements without knowing their nutritiona status, i.e. their circulating levels of nutrients (or nutrient related biomarkers).
In an upcoming article I will go into what parameters to especially look out for, how to interpret reference “normal” ranges, and what you should do if your levels are not in the ideal health promotion range, which is not equivalent to the normal range. Stay tuned…


1.            Bhasin, S., et al., Reference ranges for testosterone in men generated using liquid chromatography tandem mass spectrometry in a community-based sample of healthy nonobese young men in the Framingham Heart Study and applied to three geographically distinct cohorts. J Clin Endocrinol Metab, 2011. 96(8): p. 2430-9.

2.            Haring, R., et al., Age-specific reference ranges for serum testosterone and androstenedione concentrations in women measured by liquid chromatography-tandem mass spectrometry. J Clin Endocrinol Metab, 2012. 97(2): p. 408-15.

3.            Crabbe, P., et al., Part of the interindividual variation in serum testosterone levels in healthy men reflects differences in androgen sensitivity and feedback set point: contribution of the androgen receptor polyglutamine tract polymorphism. J Clin Endocrinol Metab, 2007. 92(9): p. 3604-10.

4.            Francomano, D., et al., CAG repeat testing of androgen receptor polymorphism: is this necessary for the best clinical management of hypogonadism? J Sex Med, 2013. 10(10): p. 2373-81.

5.            Liu, C.C., et al., The impact of androgen receptor CAG repeat polymorphism on andropausal symptoms in different serum testosterone levels. J Sex Med, 2012. 9(9): p. 2429-37.

6.            Zitzmann, M., The role of the CAG repeat androgen receptor polymorphism in andrology. Front Horm Res, 2009. 37: p. 52-61.

7.            Garmendia Madariaga, A., et al., The incidence and prevalence of thyroid dysfunction in Europe: a meta-analysis. J Clin Endocrinol Metab, 2014. 99(3): p. 923-31.

8.            Hollowell, J.G., et al., Serum TSH, T(4), and thyroid antibodies in the United States population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III). J Clin Endocrinol Metab, 2002. 87(2): p. 489-99.

9.            Shapira, N., Women's higher health risks in the obesogenic environment: a gender nutrition approach to metabolic dimorphism with predictive, preventive, and personalised medicine. EPMA J, 2013. 4(1): p. 1.

10.          Knudsen, N., et al., Small differences in thyroid function may be important for body mass index and the occurrence of obesity in the population. J Clin Endocrinol Metab, 2005. 90(7): p. 4019-24.

11.          Fox, C.S., et al., Relations of thyroid function to body weight: cross-sectional and longitudinal observations in a community-based sample. Arch Intern Med, 2008. 168(6): p. 587-92.

12.          Bjergved, L., et al., Thyroid function and body weight: a community-based longitudinal study. PLoS One, 2014. 9(4): p. e93515.

13.          Laurberg, P., et al., Thyroid function and obesity. Eur Thyroid J, 2012. 1(3): p. 159-67.

14.          Cooper, D.S. and B. Biondi, Subclinical thyroid disease. Lancet, 2012. 379(9821): p. 1142-54.

15.          Khandelwal, D. and N. Tandon, Overt and subclinical hypothyroidism: who to treat and how. Drugs, 2012. 72(1): p. 17-33.

16.          Davison, S.L. and S.R. Davis, Androgenic hormones and aging--the link with female sexual function. Horm Behav, 2011. 59(5): p. 745-53.

17.          Davis, S.R., Androgen therapy in women, beyond libido. Climacteric, 2013. 16 Suppl 1: p. 18-24.

18.          Medline Plus. Comprehensive metabolic panel. Available at (accessed July, 2016).

19.          Lab Tests Online. Comprehensive metabolic panel (CMP). Available at (accessed July, 2016).

20.          Nordestgaard, B.G., et al., Fasting is not routinely required for determination of a lipid profile: clinical and laboratory implications including flagging at desirable concentration cut-points-a joint consensus statement from the European Atherosclerosis Society and European Federation of Clinical Chemistry and Laboratory Medicine. Eur Heart J, 2016.

21.          Blaak, E.E., et al., Impact of postprandial glycaemia on health and prevention of disease. Obes Rev, 2012. 13(10): p. 923-84.

22.          Lind, M., et al., The association between HbA1c, fasting glucose, 1-hour glucose and 2-hour glucose during an oral glucose tolerance test and cardiovascular disease in individuals with elevated risk for diabetes. PLoS One, 2014. 9(10): p. e109506.

23.          Peter, R., et al., Postprandial glucose - a potential therapeutic target to reduce cardiovascular mortality. Curr Vasc Pharmacol, 2009. 7(1): p. 68-74.

Last modified on Saturday, 24 September 2016 22:35
Monica Mollica

Medical Writer & Nutritionist

MSc in Nutrition

University of Stockholm & Karolinska Institute, Sweden 

   Baylor University, TX, USA

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