Dr. Kevin Most: Blood Tests
How many times has your doctor said, “ we will get some blood tests” and you are handed a piece of paper that looks like a foreign language or a menu from another country. Often we blindly take the paper order go to the lab and let them take tubes of blood out of us, with many concerned that all their blood will be gone.
I thought we would take a few minutes and discuss common blood tests, what to expect, what tests should you have, and what is new and exciting in blood testing.
First a little trivia for you, the average sized adult has about 1.5 gallons of blood in their body, that comes out to 12 pints of blood. Blood is made from within our bones, the kidney will actually secrete a hormone to tell the body it is time to make more blood. The average age of a blood cell is 120 days after which point it is removed from circulation by the spleen. The spleen acts a recycling plant by keeping the important parts of the red blood cell to be used again. For those of you who donate blood, the blood you donate is totally replaced in your body within 4- 8 weeks. For a simple blood draw of a few tubes of blood, that blood is replaced within days and makes no impact on your total blood volume.
When we say blood, it is often used as a generic word. Our blood actually is a lot more than red blood cells. It can be broken down to red blood cells, white blood cells, plasma and platelets. Each portion of our blood has important roles. Red blood cells carry oxygen to the body and return carbon dioxide to the lungs, White blood cells fight infections and act as a major portion of our immune system, platelets stop bleeding from advancing and plasma carries other factors needed to clot blood. When the blood is clotted we are left with serum which contains, lipids, electrolytes, hormones, proteins and antibodies to list a few.
You may notice when the tech is drawing your blood that they are using tubes with different color tops. The reason for this is that the tubes are treated with chemicals to make sure that the component you are measuring will be accurate. For example, if the tube has no chemicals in the tube, the blood will clot as it should, however if we are looking at components that allow the blood to clot we don’t want them all used up, or if we want to count red blood cells we can’t count them if they are all clotted and clumped together. So next time you have blood drawn watch as they change tubes and look for the different colors. You will now know why they do that.
So when you hear you are going to have blood tests it is important to understand exactly what they are testing for. The tests are done for many reasons and are specific for the indication being tested for. For example if we are concerned about an infection we will often do a White Blood cell count. We do this because when the body is under stress from an infection it will produce more white Blood cells to help fight the infection, so our WBC count will go up and give the doctor an idea as to how severe the bacterial infection is. What is unique is that viral infections actually cause the WBC count to drop in many cases as the virus impacts the production of WBC’s for a short time.
Doctors will order blood tests that give them specific information to a condition that they are concerned about. What about when you are having a physical and the doctor orders basic tests, what are they looking for? The doctor at this time is looking at your body as a whole and not honing in on any specific disorder. In these cases he is essentially doing the same as your car dealer does with their multipoint inspection.
Let’s go over the most common tests your doctor may order and what the doctor is checking with each.
1. Comprehensive metabolic Panel- this is a panel of tests that may include close to 30 different tests. These tests will give a snapshot of your kidney function, your liver function, your gall bladder function, your nutritional status, diabetes and your cholesterol. They can do all of these tests out of a simple tube of blood. They will ask you to fast for this as some portions of your cholesterol as well as your blood sugar will be impacted with any recent food intake.
2. Complete blood count- this test will look at your White Blood cells, including the number of WBC’s as well as what type of white blood cells. Red Blood cells are counted as well including both number of red blood cells but also sizes of the red blood cells. It will also look at how many platelets we have, which is important for blood clotting. These tests are not only signals of general health but also for leukemia, anemia and iron deficiency.
3. Lipid Panel- this test looks at our cholesterol and takes it beyond just a total value for our cholesterol. The test breaks it down into our good cholesterol- HDL, our bad Cholesterol – LDL and our very bad cholesterol- VLDL. HDL is good cholesterol as it removes harmful material from our blood. The bad cholesterols are bad because they need to blockage in our arteries.
4. Hemoglobin A1c- we discussed how eating can impact your blood sugar level for a period of time while the body reacts to the intake. Patients with diabetes work to keep their blood sugar level in a tight range by checking their sugars throughout the day with finger sticks to check the glucose levels. This test will give an idea of a sugar range that your body has been in for the past 120 days as it measures how much sugar is in the Red Blood Cells which circulate for 120 days. This gives the doctor and the patient a better idea as to how well their blood sugar is doing for a long period of time
5. Thyroid Function – we don’t discuss the thyroid much, that small gland that sits in our neck and is the powerhouse for our energy. If the thyroid is working well our energy level is where we need it. When it is not functioning at the right level, often low level, or hypo thyroid, we feel sluggish, fatigued and sometimes depressed. When it is working too much or hyperthyroid our heart may race, we may feel anxious and we may struggle to keep on weight.
These are just a few of the common tests that a physician may order as part of your checkup. It is important that you understand why a test is being done, when you will get the results back and who will explain them to you. Also you want to know how the results compare with your previous tests as slight changes may show a trend that needs more evaluation , intervention or possibly medication. It is good to have your own copy of your test results, with the electronic health record these are often available to you on your phone, in some cases as soon as the test is completed. For some individuals this is good as they know the goal for their diabetes or cholesterol, for others it is not great as many jump to conclusions after seeing a single blood test and then running off to Google the results. Abnormal results should be discussed with your physician or nursing staff, this should include a discussion of what the results mean, what you need to do, and what is the follow up on this abnormal result.
What is on the horizon for blood tests- some very exciting news
There are a few new blood tests worth discussing, three were reported recently.
ABBOTT Concussion blood test
2 weeks ago, Abbott reported the results of a study that showed their blood test for concussions could detect a concussion even when it was not noted on CT Scan. The blood test looks for proteins that are only found in the brain unless there is damage to the brain which allows it to be found in circulating blood stream. The test can be done in real time and takes about 15 minutes to get results, even on the sidelines of a football game or in the ER following some trauma. This test is very important as it may give a definitive answer to the question of a concussion. This information is very important as the current concussion testing is not completely accurate. An accurate diagnosis is key as removing the individual from activities that may result in another concussion is very necessary to minimize long term effects. This study showed that the test was much more accurate than any cognitive and physical exam screening and was also more exact than a CT scan. The test is not commercially available in the US yet but is expected to be soon.
This is important as a study out last week shows that repetitive mild impact to head is causing damage to the blood vessels in the brain. The study reports that repetitive impacts to the head not necessarily the big concussive blows are likely to changes to the micro vessels that deliver blood to our brain. If this blood test can identify those individuals as well we may see a much safer and accurate way to prevent the long term effects of concussions
Cancer SEEK is a blood test that we have discussed in the past. It is a blood test that is being developed to identify 8 cancers from a single tube of blood. Essentially a liquid biopsy. The test will look for known DNA fragments from cancers that would be circulating in the blood stream. What is more interesting is the cancers this test may be able to identify. The current list includes Breast, lung, colon, ovarian, liver, stomach and pancreatic. As you look at this list, imagine that the test is perfected to a point where it can identify the cancer before traditional ways of testing, identify it earlier and more accurately.
The list includes some cancers that when identified are beyond the option for successful treatment. Lung cancer, ovarian cancer and pancreatic cancer comes to mind. Think about being able to eliminate the need for mammograms or colonoscopies to diagnose those two common cancers. The current stand is that this test will complement the current screening tools
Is this futuristic or is it something we will see soon? It may be here sooner than we think. It is currently in a large study and earlier studies have shown it to be quite good. The study that came out last year showed it to be quite accurate for ovarian, liver, pancreas, stomach and esophageal cancer, each of these very important as there are currently no screening test for each of these. The proposed price for this test is $500, which is a very appealing price for both patients and insurers. The ability to identify these cancers early will be lifesaving and game changing. Look for more information on this as well as the ability to potentially participate in a clinical trial, as they work to perfect this test.
LIFESPAN Blood Test
The other test is a bit more controversial, a group of researchers in Europe, are looking to design a blood test that could predict your lifespan as you age. The study is taking data from close to 45,000 individuals aged 18-109. During the follow up period 5,500 of the individuals had passed away. The researchers then looked at biomarkers in the blood and took that data to see if they could create a scoring system that would predict when a person might die. The researchers identified 14 different biomarkers in the blood, when some were found at low levels the chance of death was high, while other biomarkers when found at higher levels were associated with a lower chance of death. The data is being reviewed to see if levels could predict within a timeframe what the future life expectancy would be.
This obviously will be met with resistance from ethical view from a psychological view and from a healthcare utilization view. The concern about rationing health care would be raised quickly, along with utilization. If someone had this test and the results showed a predictive score that the patient would die within 5-10 years what would we do differently? Would we not do some surgery, would we not use expensive medications, would we give limited resources to an individual who had a better score. Would individuals make other life changing decisions based on the knowledge that they have a high chance of dying within the next 5 years. Many may argue that this is good information and that if we can predict our life span why wouldn’t we want to know. It would allow us to make choices on work life balance, allow us to make financial decisions, and family and friend decisions.
Probably the biggest issue as this research is more publically available, would be can we change our lifestyle to change these biomarkers and improve or extend our lives. Would we start to track things we never thought were important, like our levels of leucine or valine. Would we find medications that could lower inflammation should be used as regularly as statin drugs are now.
There will be more to come on this study and how its results will be used in routine care in the future.