Blood tests: which ones to get and what the heck do they mean?

Most people have had blood tests taken but the majority don’t know what they mean. I've asked countless patients about their results for diabetes testing, kidney, liver function and lipids panels and many wouldn’t have a clue what they’ve had done or what the results mean apart from saying their GP said “they were OK”…. or not. Personally, I don’t think that's good enough. Those test results are yours and it should be your responsibility to know what they are and what they mean and if you don’t know, ask. You cannot take charge of your health unless you know what is actually going on. It’s possible your GP or physician may be too busy to give you a full explanation, so in this post I will try to explain what tests to look at and what the numbers mean in relation to your metabolic health. It is also likely that your doctors may not know what exactly to look for so this will act as a primer for you to be well informed, maybe even better than your doctor.

So if you’ve been playing along at home and had your bloods done that I mentioned in my second post we’ll go through the results now as well as a few other tests:

Fasting insulin

Fasting glucose

HbA1C

Liver function tests

Lipids/Cholesterol panel

Kidney function

hsCRP

Ferritin

Vit D level

Thyroid function

Fasting Insulin level: Quoted normal level 2-12

This is probably the most important test of your metabolic health that you can easily get done. Without knowing what your insulin level is, you really have little idea about where you stand on the spectrum from good metabolic health with insulin sensitivity to some degree of insulin resistance to overt prediabetes. The “normal” level for insulin is quoted to be anything up to 12. This level is obtained from looking at the average population and seeing what the fasting insulin level is in most people. As I've previously mentioned, if most people are metabolically unhealthy, then it's likely that they will have an elevated insulin level. This means that the normal levels for a population on average are falsely elevated.

For good metabolic health, that is when you are insulin sensitive - meaning your body responds appropriately to insulin - you should be aiming to have your fasting insulin level less than 7. If your insulin level is higher than this, it means that you are requiring more insulin in your body to produce the effect of keeping your blood sugar levels stable even when you’re not eating (fasted state). Think of it like this. If you drink alcohol consistently at a high level your body becomes used to it and over time it needs more and more alcohol to produce the same intoxicating effect. Our bodies in effect are becoming more and more resistant to the effects of alcohol. Similarly, with more and more insulin being produced by the pancreas in response to a high carbohydrate diet our bodies are gradually becoming resistant to the normal effects of insulin and require increasing amounts to produce the same blood sugar lowering effect. This means that you now have insulin resistance -  a state where insulin isn’t producing the same result as earlier and more insulin is required. The problem here is that with time, more and more insulin is required to keep blood sugar levels in the normal range as the body becomes more and more resistant to its effects. This increased insulin level then leads to conditions such as diabetes, heart disease, obesity, polycystic ovarian syndrome, some cancers and poor lipid markers. 

PLEASE NOTE: Just because you think you’re skinny or normal weight doesn’t mean that you can’t have high insulin levels. So everyone needs to have this checked as it may be one of the indicators that you are a TOFI (thin outside, fat inside) and at high risk for diabetes, no matter what your age, cultural background or gender.

Knowing what your insulin level is can help predict your chance of developing diabetes in the future, possibly up to 10-15 years in advance and if it's elevated above 7 then you can do something about it to prevent the progression to full blown diabetes.

Glucose in yellow stays normal for 10-15 years while Insulin in green is already increasing. Only after many years of high insulin levels and the development of insulin resistance does the blood glucose start to rise at which point mainstream medicine makes a diagnosis of type 2 diabetes. However testing for fasting insulin can diagnose early insulin resistance and appropriate steps can be taken at this point to reverse this.

Image courtesy Why We Get Sick, Benjamin Bikman, PhD

Unfortunately insulin is rarely checked by GPs and this important early marker of metabolic syndrome can and usually does go undetected for years. The main focus is Glucose and HBA1C which can remain relatively normal until the insulin level and degree of insulin resistance becomes very high and the insulin can longer keep blood glucose levels under control. Along with this the pancreas which produces these high levels of insulin also starts to fail and the production of insulin falls by 30-50%. (1)  It is only at this point that glucose levels will become high and your GP will diagnose you with Type 2 Diabetes but by now, the damage from chronically elevated insulin levels has been present for many years.

If your Insulin level is high, you can directly affect this by lowering your carbohydrate intake which will reduce insulin secretion and stabilise bloods glucose fluctuations. High insulin levels, insulin resistance, pre-diabetes and diabetes can all be thought of as a reaction to too many carbs and sugars in the diet. Essentially what we’re dealing with is carbohydrate toxicity, where the body cannot safely deal with the amount of carbohydrates being ingested. Decrease the carbs and sugars and the toxicity can be reversed.

Think of it this way… if you’re lactose intolerant you need to avoid milk. If you’ve got a shellfish allergy you avoid shellfish so if you’re proven to be intolerant to sugars and carbohydrates by having a high insulin level cut them out. 

Fasting glucose 

This level should be well under 7.0 and preferably less than 5.5. If your fasting Glucose is higher than this then you are either a pre-diabetic or a diabetic already. 

HBA1C

HBA1C (Haemoglobin A1C) gives you a pretty good idea of what your average blood glucose is over a period of 3 months. In general you want this to be less than 5.3. If the result is between 5.7- 6.4 you’re in the pre-diabetes phase and if over 6.5 you’re a diabetic.

Liver Function Tests

Within a standard liver function test panel there are many individual tests. The ones we are mainly interested in here are the following:

ALT (Alanine Transaminase): should be less than 25 

GGT (Gamma-glutamyl Transferase): should be less than 25

These two tests can be elevated for a number of reasons, for example, from chronic excessive alcohol consumption but they are also elevated in metabolic syndrome due to Non Alcoholic Fatty Liver Disease (NAFLD). They can also be elevated from other causes of liver disease and from the effect of some medications. If you are not aware of any other liver conditions, you're not on any regular medications and you don’t drink excessively but these levels are still elevated, you may well have NAFLD. This is something your doctor can further investigate with an ultrasound scan and if it’s positive it’s is a very strong indicator that you have metabolic problems. Fortunately, NAFLD can also be reversed by limiting those offending carbohydrates.

Lipid/Cholesterol Panel 

Now this is a super controversial area and I encourage you to do your own research. There is plenty written on this topic from both sides of the argument and there is a lot that is still unknown. 

The orthodox teaching here is we need to be concerned about LDL cholesterol and Total Cholesterol. Personally, from everything I have read in the past couple of years I am the least concerned about these two markers and would rather focus my attention on Triglyceride count and HDL.

The traditional diet-heart-hypothesis view has Cholesterol and LDL cholesterol as the main cause of atherosclerosis (blockages of the arteries) causing heart disease. This has been demonstrated to be false in many studies and reviews (1) but unfortunately this view is still widely held and it has been drummed into us for the past 50 years along with the eat fat - get fat - fat raises your LDL - LDL causes heart disease mantra. It is the reason why people are started on and then maintained on statin drugs for decades often with very little benefit and it may even cause them harm. There is a place for statin medications but it should probably be for specific people and problems.

The alternate view when looking at the basic lipid panel places more importance on the Triglyceride (TG) level and HDL level and the ratio of one to the other. An elevated fasting TG level usually occurs when there is excess energy circulating in your bloodstream and there is nowhere for it be stored. This occurs when the liver is made to produce fat from excess fructose and glucose and is unable to store it any longer as its own reserves are full so it pumps it out into the bloodstream hoping that the fat reserves in the body will take it up. When these are full as well, the excess triglycerides remain in the circulation and they can be measured. So an elevated fasting TG level in the blood is a sign that your metabolic health is compromised. You should be aiming to get your TG level less than 1.0

Along with the elevated TG level, a low level of HDL cholesterol (or good cholesterol) as some people refer to it, is also a marker of metabolic dysfunction. Low levels of HDL are associated with increased rates of heart disease as HDL molecules are thought to play a role in clearing damaged LDL cholesterol particles out of blocked arteries. Unfortunately attempts to raise HDL with specific drugs have been so far unsuccessful. However, improving your metabolic health by lowering your insulin resistance actually raises your HDL and lowers your TG level at the same time. In fact, the ratio of TG level to the HDL level is a fairly good predictor of good metabolic health as well as a good predictor of whether the LDL particles you have are the potentially damaging type or not. You should be aiming for a HDL higher than 1.55 and a ratio of TG/HDL ration less than 1.

The alternate view of LDL takes a more nuanced look at these particles. It has been shown that LDL particles can come in various sizes. Large LDL particles are thought to be less harmful and are also involved in immune function and defence as well as energy transfer, whereas the smaller dense LDL particles are the ones more implicated in the formation of atherosclerosis or blockages. So what makes these LDL particles smaller and more dangerous? The presence of high blood sugar levels and fructose accelerates the ageing process of cells (oxidation) and when this occurs to LDL, a smaller and denser LDL particle results. This can also occur in the presence of inflammatory substances such as high insulin levels and polyunsaturated oils (PUFA’s) or seed oils usually known as vegetable oils. These smaller particles also tend to stay in the blood stream longer as they aren't removed properly by the liver. This means they have more of a chance to become involved in the atherosclerotic/blockage process. (2,3)

It is possible to have a test to determine whether you have small or large LDL particles but it probably doesn’t need to be a first line test. If your TG level is low and HDL level is high that is a pretty good indication that you predominantly have large LDL particles and not a high number in circulation. This test may be more useful if your LDL level is very high as sometimes happens in people with excellent metabolic health where they discover they usually have the large type or, if you have been diagnosed with some type of atherosclerotic heart disease and you are having further investigation done. A fantastic review of all things lipids is by Dr. Ron Krauss which can be heard here https://www.dietdoctor.com/diet-doctor-podcast-9-dr-ron-krauss

Kidney Function 

All these results should be in the normal range. Elevations of the urea/creatinine and or GFR are signs that the kidneys are working sub optimally and this needs to be investigated further. Many reasons exist for this including high blood pressure, high insulin levels, diabetes as well as a myriad of other causes. 

hsCRP: high sensitivity C Reactive Protein <1

This is a protein that is made in the liver. It is usually found in very low levels in the blood but be can elevated in inflammatory conditions, autoimmune disorders, infections and cancers. Because many things can elevate the level, it is a very non specific test. However if you don’t have an active infection, cancer or autoimmune condition that you know of, it is a sign that there may be some inflammation going on in your body and this needs to be investigated for more thoroughly. A level above 1 would mean that some inflammation is present.

Ferritin: 50-300ng/ml

Similar to hsCRP, an elevated ferritin level can also be an indication that there is inflammation in the body. It is also a non specific marker as it can be elevated for other reasons such as haemochromatosis. 

Vitamin D level: optimal higher than 75nmol/L

I will do a whole post on the importance of Vitamin D in the near future but it's been shown to be more important to us than just for bone health. Higher levels are associated with better immune function, less risk of dying from infections and overall longevity. 

Thyroid function TSH <3.0, T4 upper half of normal quoted range.

A whole post in itself due to the complexity of its interaction with our metabolism. It is important to check your thyroid level in your routine tests because if it's under or over active it can have major consequences on your metabolic health and can be influenced by what you eat. More on this later.

(1) https://www.diabetesaustralia.com.au/type-2-diabetes

(2) Ravnskov et al; LDL-C does not cause cardiovascular disease: a comprehensive review of the current literature. 2018 Expert Review of Clinical Pharmacology, 11:10, 959-970, https://doi.org/10.1080/17512433.2018.1519391

(3) Hoogeveen et al. Arteriosclerosis, Thrombosis, and Vascular Biology. 2014;34:1069–1077 https://doi.org/10.1161/ATVBAHA.114.303284

(4) St-Pierre et al.Arteriosclerosis, Thrombosis, and Vascular Biology. 2005;25:553–559 https://doi.org/10.1161/01.ATV.0000154144.73236.f4