In this article, I’ll address a real mainstay of modern medicine: laboratory tests that require drawing blood.
This is sometimes referred to as “checking labs,” “doing bloodwork,” or even “checking blood.”
Most older adults have been through this. For instance, it’s pretty much impossible to be hospitalized without having bloodwork done, and it’s part of most emergency room care. Such testing is also often done as part of an annual exam, or “complete physical.”
Last but not least, blood testing is usually — although not always — very helpful when it comes to evaluating many common complaints that affect aging adults.
Fatigued and experiencing low energy? We should perhaps check for anemia and thyroid problems, among other things.
Confused and delirious? Bloodwork can help us check on an older person’s electrolytes (they can be thrown off by a medication side-effect, as well as by other causes). Blood tests can also provide us with information related to infection, kidney function, and much more.
Like much of medical care, blood testing is probably overused. But often, it’s an appropriate and an important part of evaluating an older person’s health care concerns. So as a geriatrician, I routinely order or recommend blood tests for older adults.
Historically, laboratory results were reviewed by the doctors and were only minimally discussed with patients and families. But today, it’s becoming more common for patients to ask questions about their results, and otherwise become more knowledgeable about this aspect of their health.
In fact, one of my top recommendations to older adults and family caregivers is to always request a copy of your laboratory results. (And then, keep it in your personal health record!)
This way, if you ever have questions about your health, or need to see a different doctor, you’ll be able to quickly access this useful information about yourself.
In this article, I’m going to list and briefly explain the blood tests that are most commonly used, for the primary medical care of older adults.
Specifically, I’ll cover four “panels” which are commonly ordered, and then I’ll list six more blood tests that I find especially useful.
In other words, we’re going to cover my top ten blood tests for the healthcare of aging adults.
I’ll finish with some practical tips for you to keep in mind, when it comes to blood tests.
4 common “panels” in laboratory blood testing
1. Complete Blood Count (CBC)
What it measures: A CBC is a collection of tests related to the cells in your blood. It usually includes the following results:
- White blood cell count (WBCs): the number of white blood cells per microliter of blood
- Red blood cell count (RBCs): the number of red blood cells per microliter of blood
- Hemoglobin (Hgb): how many grams of this oxygen-carrying protein per deciliter of blood
- Hematocrit (Hct): the fraction of blood that is made up of red blood cells
- Mean corpuscular volume (MCV): the average size of red blood cells
- Platelet count (Plts): how many platelets (a smaller cell involved in clotting blood) per microliter of blood
The CBC can also be ordered “with differential.” This means that the white blood cells are classified into their subtypes. For more information on the CBC test, see Medline: CBC blood test. For details on the white blood cell count differential, and what the results might signify, see Medline: Blood differential test.
What the CBC is often used for:
- Anemia may be diagnosed if the red blood cell count, hemoglobin, and hematocrit are lower than normal.
- I explain anemia in more depth here: Anemia in the Older Adult: 10 Common Causes & What to Ask.
- The white blood cell count usually goes up if a person is fighting an infection. Some medications, such as corticosteroids, can also cause an increase in the white blood cell count.
- If several types of blood cells (i.e. red blood cells, white blood cells, and platelets) are low, this can be a sign of a problem with the bone marrow.
- Occasionally an older person’s platelet count may be lower than normal (or even higher than normal). This usually requires further evaluation.
2. Basic metabolic panel (basic electrolyte panel)
What it measures: Although it’s possible to request a measurement of a single electrolyte, it’s far more common for electrolytes to be ordered as part of a panel of seven or eight measurements. This is often referred to as a “chem-7,” and usually includes:
- Sodium
- Potassium
- Chloride
- Carbon dioxide (CO2) (sometimes referred to as “bicarbonate,” as this is the chemical form of carbon dioxide which is more common in the bloodstream)
- Blood urea nitrogen (BUN)
- Creatinine (often accompanied by an estimated “glomerular filtration rate,” or “eGFR”result)
- Glucose
What the basic metabolic panel is often used for:
- Medication side-effects can cause electrolytes such as sodium or potassium to be either too high or too low.
- These electrolytes are often monitored when people take certain types of medications, such as certain blood pressure medications, or diuretics.
- Carbon dioxide levels reflect the acidity of the blood.
- This can be affected by kidney function and by lung function. Severe infection can also change acid levels in the blood.
- Creatinine and BUN levels are most commonly used to monitor kidney function. Both of these measurements can go up if kidney function is temporarily impaired (e.g. by dehydration or a medication side-effect) or chronically impaired.
- It is common for older adults to have at least mild decreases in kidney function.
- Many medications must be dosed differently, if a person has decreased kidney function.
- Laboratories now routinely use the patient’s age and creatinine level to calculate an “estimated glomerular filtration rate,” which represents the filtering power of the kidneys. This is considered a better measure of kidney function than simply relying on creatinine and BUN levels.
- Glucose levels represent the amount of sugar in the blood.
- If they are higher than normal, this could be due to undiagnosed diabetes or inadequately controlled diabetes.
- If the glucose levels are on the low side, this is called hypoglycemia. It is often caused by diabetes medications, and may indicate a need to reduce the dosage of these drugs.
For more details on these tests, see Medline: Basic Metabolic Panel. From this page, you can find links to additional pages which explain each of the above electrolytes and metabolic components in detail, including common causes of the result being abnormally high or low.
3. Comprehensive metabolic panel
What it measures: This panel includes the items above in the basic metabolic panel, and then usually includes an additional seven items. For this reason, it’s sometimes referred to as a “chem-14” panel. Beyond the seven tests included the basic panel (see above), the comprehensive panel also adds:
- Calcium
- Total protein
- Albumin
- Bilirubin (total)
- Alkaline phosphatase
- AST (aspartate aminotransferase)
- ALT (alanine aminotransferase)
What the comprehensive metabolic panel is often used for:
- Calcium levels are usually regulated by the kidneys and by certain hormones.
- Blood calcium levels are not usually a good way to assess calcium intake or total calcium stores in the bones and body.
- High or low blood calcium levels can cause symptoms, including cognitive dysfunction, and usually indicate an underlying health problem. They can also be caused by certain types of medication.
- Albumin is one of the key proteins in the bloodstream. It is synthesized by the liver.
- Low albumin levels may indicate a problem with the liver or a problem maintaining albumin in the bloodstream.
- Malnutrition may cause low albumin levels.
- AST and ALT are enzymes contained in liver cells.
- An elevation in these enzymes often indicates a problem affecting the liver. This can be caused by medications or by a variety of other health conditions.
- Bilirubin is produced by the liver, and usually drains down the bile ducts and into the small intestine. Some bilirubin is also related to the breakdown of red blood cells.
- An increase in bilirubin can be caused by gallstones or another issue blocking the bile ducts.
- Alkaline phosphatase is found throughout the body, but especially in bile ducts and also in bone.
- Higher levels are often caused by either a blockage in the liver or by a problem affecting bone metabolism.
For more details on these tests, and the possible causes of abnormal results, see Medline: Comprehensive Metabolic Panel.
4. Lipid (cholesterol) panel
What it measures: These tests measure the different types of cholesterol and related fats in the bloodstream. The panel usually includes:
- Total cholesterol
- High-density lipoprotein (HDL) cholesterol, sometimes known as “good” cholesterol
- Triglycerides
- Low-density lipoprotein (LDL) cholesterol, sometimes known as “bad” cholesterol
- LDL results are usually calculated, based on the other three results
People are often asked to fast before having their cholesterol checked. This is because triglycerides can increase after eating, and this can cause a falsely low LDL to be calculated. However, experts have recently concluded that in most cases, it’s not necessary for people to fast; it’s inconvenient and only makes a small difference in test results.
What the lipid panel is often used for:
- These tests are usually used to evaluate cardiovascular risk in older adults.
- Higher than normal total or LDL cholesterol levels are sometimes treated with a medication, such as a statin. They can also be reduced by dietary changes (see Your Guide to Lowering Cholesterol with Therapeutic Lifestyle Changes, from the NIH).
- For more on these tests, see Medline: Cholesterol testing and results.
6 more blood tests that I order often
Here are six other types of tests that I often order on my older patients:
1. Tests related to thyroid function
What these measure: These tests can be used to screen for thyroid disorders, or to help calibrate the dosage of thyroid replacement medications. The most commonly used tests are:
In more complicated situations, other tests related to thyroid function may also be ordered.
What these tests are often used for:
- Thyroid problems are common in older adults (especially older women), and are associated with symptoms such as fatigue and cognitive difficulties.
- If an older person is having symptoms that could be related to a thyroid problem, the first step is to check the TSH level.
- TSH usually reflects the body’s determination of whether the available thyroid hormone is sufficient or not.
- If the thyroid gland is not making enough thyroid hormone, TSH should be higher than normal.
- Free T4 is often used to confirm a thyroid hormone problem, if the TSH is abnormal.
For more information about thyroid problems in older adults, see HealthinAging.org: Thyroid Problems. You can also read a more in-depth scholarly article here: Approach to and Treatment of Thyroid Disorders in the Elderly.
2. Tests related to vitamin B12 levels
What these measure: These measure the serum levels of vitamin B12 and provide information as to whether the level is adequate for the body’s needs. The two tests involved are:
Depending on the situation, if an older adult is found to have low vitamin B12 levels, additional testing may be pursued, to determine the underlying cause of this vitamin deficiency.
What these tests are often used for:
- Vitamin B12 deficiency is quite common in older adults, and can be related to common problems such as fatigue, memory problems, and walking difficulties.
- Methylmalonic acid levels in the body are related to vitamin B12 levels, and can help confirm a vitamin B12 deficiency.
- It is especially important to check this, if an older person has vitamin B12 levels that are on the low side of normal.
- Low vitamin B12 levels are associated with higher-than-normal methylmalonic acid levels
- For more information, see: How to Avoid Harm from Vitamin B12 Deficiency.
3. Glycated hemoglobin (Hemoglobin A1C)
What it measures: Glycated hemoglobin is formed in the body when blood glucose (blood sugar) attaches to the hemoglobin in red blood cells. It is normal for glucose to do this, but if you have more glucose in the blood than normal, your percentage of glycated hemoglobin will be higher than normal. The higher one’s average blood sugar level, the greater percentage of glycated hemoglobin one will have. A result of 6.5% or above is suggestive of diabetes. For more information:
What this test is usually used for:
- This test is most often ordered to monitor the blood sugar control of people with diabetes.
- Whereas a blood glucose level (which can be checked by fingerstick or as part of a basic metabolic panel) reports the blood gluose level at a specific moment in time, a hemoglobin A1C reflects how high a person’s blood sugar has been, on average, over the prior three months.
- A hemoglobin A1C test can also be used as part of an evaluation for possible diabetes or pre-diabetes.
- Older adults should work with their doctors to determine what A1C goal is right for them. It is often appropriate to aim for a slightly higher goal in older adults than in younger adults. For more on this, see HealthinAging.org: Diabetes Care & Treatment.
4. Prothrombin time (PT) and International Normalized Ratio (INR)
What it measures: These two tests are used as a measure of how quickly a person’s blood clots. People taking the blood-thinner warfarin (brand name Coumadin) must have this regularly monitored. For more information:
What this test is usually used for:
- The INR is calculated by the laboratory, based on the prothrombin time. In people taking warfarin, the usual goal is for the INR to be between 2.0 and 3.0.
- The most common reason older adults take warfarin is to prevent strokes related to atrial fibrillation.
- Warfarin may also be prescribed after a person has experienced a blood clot in the legs, lungs, or elsewhere.
- The prothrombin time is also sometimes checked if there are concerns about unexplained bleeding, severe infection, or the ability of the liver to synthesize clotting factors.
5. Brain natriuretic peptide (BNP) test
What it measures: Despite the name, BNP levels are mainly checked because they relate to heart function (not brain function!). BNP levels go up when a person’s heart cannot pump blood as effectively as it should, a problem known as “heart failure.” For more information on this test:
A related, but less commonly used, test is the “N-terminal pro-B-type natriuretic peptide” (NT-proBNP) test.
What this test is used for:
- Checking a BNP level is mainly used to evaluate for new or worsening heart failure. This is a common chronic condition among older adults, which can occasionally get worse.
- The BNP test can be especially useful in evaluating a person who is complaining of shortness of breath.
- Shortness of breath can be caused by several different problems, including pneumonia, chronic obstructive pulmonary disease, pulmonary edema, angina, and much more.
- A low BNP level means that at that moment, the shortness of breath is unlikely to be due to heart failure.
- Checking BNP levels over time is also sometimes used to monitor a person’s heart failure and response to treatment.
- For more about heart failure, see MayoClinic.org: Heart failure tests and diagnosis and also HealthinAging.org: Heart failure.
6. Ferritin
What it measures: The body’s serum ferritin level is related to iron stores in the body. For more about this test:
Depending on the situation, if an older person’s iron levels need further evaluation, additional tests can be ordered.
What this test is used for:
- Ferritin levels are most commonly used as part of an evaluation for anemia (low red blood cell count). A low ferritin level is suggestive of iron-deficiency, which is a common cause of anemia.
- Studies estimate that only a third of anemias in older adults are due to deficiencies in iron or other essential elements.
- It’s important to confirm iron deficiency by checking ferritin or other tests, before relying on iron to treat an older person’s anemia.
- Ferritin levels are also influenced by inflammation, which tends to make ferritin levels rise.
- If the ferritin levels are borderline, or if there are other reasons to be concerned about an older person’s ability to manage iron, additional blood tests related to iron may be ordered.
- For more on evaluating and treating anemia in older adults, see Anemia in the Older Adult: 10 Common Causes & What to Ask.
Obviously, there are many more tests that can be ordered as part of the medical care of older adults. But the tests I cover above are, by far, the ones I order the most often.
Tips to help you benefit from your blood tests and results
Here are my top tips:
1. Be sure you understand why a given test is being ordered. Is it meant to help evaluate a symptom? Monitor a chronic condition? Assess whether a treatment is working?
You will understand your own health issues better, if you ask questions about the purpose of the blood tests your doctors are proposing.
In general, blood tests should only be ordered for a reason, such as to evaluate a concerning symptom, to monitor a chronic disease, or to check for certain types of medication side-effect.
Keep in mind that it’s only occasionally appropriate to order blood tests for “screening.” A screening test means a person doesn’t have any symptoms. Such screening blood tests are only recommended for a handful of conditions.
For more on preventive health care and screening tests that may be appropriate for older adults, see 26 Recommended Preventive Health Services for Older Adults.
2. Ask your doctor to review the results and explain what they mean for your health. Try to look at the report with your doctor. It’s especially important to ask about any result that is flagged as abnormal by the laboratory system.
For instance, I have found that many older adults are unaware of the fact that they have mild or moderate kidney dysfunction, even though this has been evident in prior laboratory tests. This happens when people do not review reports and ask enough questions.
Wondering why the doctor wouldn’t tell an older person that the kidney function is abnormal?
Well, if it’s been going on for a while, the doctor might think the older person already knows about this issue. Or perhaps the doctor mentioned it before, but the older person didn’t quite hear it. It’s also not uncommon for doctors to just not get around to mentioning a mild abnormality that is pretty common in older people, such as mild anemia or mild kidney dysfunction.
3. Ask your doctor to explain how your results compare with your prior results. Laboratory reports will always provide a “normal” reference range. But what’s usually more useful is to see how a given result compares to your previous results.
For instance, if an older person’s complete blood count (CBC) shows signs of anemia, it’s very important to look at prior CBC results. This helps us determine what the “trajectory” of the blood count is. A blood count that is drifting down — or worse yet, dropping fairly suddenly — is much more concerning than one that has been lower-than-normal, but stable for the past year. Ditto test results suggesting diminished kidney function, and for many other abnormal blood test results.
Of course, you’ll want to understand what might be the cause of an abnormal result regardless of the trajectory. But a worsening blood test result usually means the issue is more urgent to sort out.
4. Request copies of your results, and keep them in your own record system. Past laboratory results provide incredibly useful information to health providers, and can be very useful to you as well.
If you keep your own copies of results, you’ll be better able to:
- Share them with new doctors, if you change health providers, move to a new city, or have to go to the emergency room.
- Research your health condition, in order to better understand it and know what questions to ask your doctor.
For instance, one of my family members recently had a “routine” cholesterol panel done. He takes no medications, is quite fit, and is in good health, so he was surprised when some of his results came back higher than normal. We promptly reviewed his previous results, from three years ago, and found that those results were within normal range. So this family member is now in the process of reconsidering his diet.
If he hadn’t had copies of his previous labs, he could have asked his doctor. But it’s much faster and more convenient to be able to look in your own records!
And don’t just rely on looking up past results through a patient portal. Clinics will often remove your access, if you are deemed to have left the practice. So it is very important to keep your own copies of results.
For more on the benefits of maintaining your own personal health record — or a health record for an older parent — see How to Use a Personal Health Record to Improve an Older Person’s Healthcare.
Do you have questions about common blood tests for older adults? Please post them below and I will do my best to address them.
Your posts are always interesting. This one is particularly helpful. Thank you so much for writing and sharing your knowledge and practical wisdom.
I’ve been a nurse for 40something years. Friends often call me to ask what I think or know about this symptom or that diagnosis for themselves or a family member. The first thing I ask is about lab work and almost always they have no idea what’s been done or what the results showed. Often they never hear back from the provider and assume”no news is good news” or, even scarier…the symptoms are no better or worse but “they said my lab work looked ok so….”. I always recommended they get hard copies of the results. Thank you for this easy to understand and very comprehensive tutorial. I’m gonna save it and hand it out.
Thank you for your feedback. I’m so glad you found this article especially helpful!
Thank You so much for your assistance with so many thing medical. We could really use a whole lot more people working in this field. That being said, it behooves all of us to manage our own care, where possible. Having dealt with Hemochromatosis for 35 years, I can say that keeping all involved focused on my bottom line takes more time than the actual treatment. Thanks again, your effort is appreciated.
Yes, coordination and organization often takes a lot of work. I am sure you have become quite adept after 35 years with a serious condition. Thank you for your feedback.
Thank you so much for your dedication and passion for the health and wellness of older adults and their caregivers.
Thank you for providing such a wonderful space for learning and sharing.
I also have an 82yo Dad I forward your articles to! He reads in prep for his physician visits.
Thank you for all you do!
Be well…
I LOVE the idea of older adults doing a little preparation before their medical visits!
Of course, I don’t want to burden people with work to do, but a little preparation can go a long way towards helping people get more of what they need — and less of what they don’t — out of their healthcare.
Thank you for your feedback, I’m delighted to hear that the articles are helpful.
You said there are ten tests that should be taken by older adults, yet you only list six. What happened to the other four tests.
The first part of the article lists four “panels” that are often ordered: CBC, basic metabolic panel, comprehensive metabolic panel, and lipid panel.
The second part of the article lists 6 additional blood tests that are often ordered.
Thank you, this is so well-timed. My 98 year old Dad just had his bi-annual physical with all lab results coming back “normal”. He wanted to know what that meant in terms of what the tests were looking for. this will help me interpret them for him!
Glad you find it helpful, thanks for letting me know. I am thrilled to hear of a 98 year old person who is learning more about what his lab work might mean!
Thanks for this detailed article! How can I know if my basic lab results are all a bit out of the normal range due to my being 64 or due to my being long term overweight in the 220-240 range? I am 5’4”. Thank you!
The best thing to do would be to discuss your results with your healthcare provider.
Although it’s common for people to have abnormal lab results as they age, these generally aren’t caused by aging per se, they are caused by a variety of health problems that become more common as people get older. Same goes for being overweight; clinicians generally shouldn’t attribute abnormal results to weight and then just stop there, they should find out just what is the problem and help you with it.
Of course if you are only a little out of the normal range, it can be hard to say whether that reflects a real problem versus just being a bit of an outlier. Again, a healthcare provider who can talk to you, examine you, and review your health history would be in a position to clarify whether your “bit out of the normal range” values are worrisome or not. It also is often helpful to repeat tests after a suitable interval (weeks to months, depending on your situation) to see if the slightly abnormal values have gone back to normal, stayed the same, or gotten worse.
Good luck!
My husand and I have been together for 48 yrs. He has donated blood for all those yrs and some. Many times he was turned down due to a lower hgb, hct and rbc. I went into nursing so I kept records of his labs over the course of 48 yrs. This has been a chronic issue I believe for most of his life. He is or was a marathon runner and ran for most of his life. He is 72 yrs old and still runs . His levels will be normal for months and many even a yr and then slightly go down. Then back up again. Everything else is always normal. Normal B12, Ferritin, Iron, etc. He is always told it is chronic. I discovered by much research that a possible cause was perhaps a methylationn issue. I started to give him converted B6 called P5P. His levels went right back up. But there are side effects with B6 and causes neuropathy. I thought he might have the MTHR gene mutation but his homocysteine levels are normal. Any thoughts of any of this. PS He also has Hashimoto thyroid , which is rare for men.
Hm, his situation sounds more complicated than most. I would recommend consulting with a specialist in hematology, if you are determined to get to the bottom of this. Of course, if it’s a long-standing issue and he is well enough to keep running at age 72, it’s unclear to me whether digging into this is likely to really improve his health, longevity, or quality of life…
Re B6, it’s true that high doses are associated with toxicity. Your husband’s health providers can probably advise him as to whether and how to safely take it. Good luck!
Just wanted to thank you for putting out this information. Sure wish there were more gerontologists in our health care system. Can we clone you? 😀 I’m sure this blog/site is a lot of work (articles are very detailed), and I really appreciate all you do!
Thank you for this nice comment. I actually HAVE been wishing I could clone myself, as there is more I want to write about for the site but I am perpetually short on time.
Small thing: a geriatrician is not quite the same thing as a gerontologist. Basically, geriatrics is medical, whereas gerontology is more broadly related to aging. All geriatricians have gone to medical school, whereas gerontologists have studied aging and obtained some form of degree or credential in gerontology.
I mention it because over the past several years, I’ve noticed that the public either is surprised to hear that a geriatrician is actually a medical doctor (yes it’s true), or they assume that a gerontologist is a medical doctor (usually not true, although they are certainly quite knowledgeable and do wonderful work and research).
Thank you once again for your interest in the site and in geriatrics!
My 63 yr old spouse recently got lab tests & his RBC was low as well as hemoglobin.
I’ve noticed the hemoglobin has gotten lower even w/adding iron supplement. He looks so pale & is exhausted. His chloride & sodium are low also.
His GP has said nothing, as a retired nurse I am concerned. What are tests we need to follow up with?
I agree it sounds concerning, especially if his hemoglobin continues to get lower and/or he is having worrisome symptoms.
I explain the evaluation and management of anemia — including how to make sure it really is due to iron deficiency — in this article: Anemia in the Older Adult: 10 Common Causes & What to Ask.
Especially if his GP is saying nothing, then you will need to ask more questions. Good luck!
Hello, My mother who is 80 has been feeling more confused and has had increased anxiety. I asked her home nurse to do some blood work. Her hemoglobin is 11.0 her RBC is 3.88 and hematocrit 35.3 Urea nitrogen serum 31 which is high. Her TSH was 0.87
I think this means she is anemic. I plan to ask her nurse to compare to her last blood work done a little over a year ago. How would I know if this is a iron defeciency or a blood loss from something internal anemia? Thank you for any advice you can give.
MCV 91
MCH 28.3
MCHC 31.1
Platelets 294
So, a hemoglobin of 11 would generally be considered mild anemia and I wouldn’t expect it to cause confusion or anxiety. Iron-deficiency usually corresponds with a lower ferritin level. You could ask about this, as it’s possible this is the cause of her mild anemia. For more on anemia see Anemia in the Older Adult: 10 Common Causes & What to Ask.
But if your main concern is confusion and anxiety, then what she needs is an evaluation for things that can cause these symptoms. Some electrolyte imbalances can do this. You could ask her doctor if anything in her labs can help explain her recent confusion and anxiety.
Otherwise, she may need further evaluation for things that cause or worsen problems with brain function, memory, and thinking. These include medication side-effects, delirium, and certain other medical problems. I explain those evaluations in these articles:
How to Diagnose & Treat Mild Cognitive Impairment
How We Diagnose Dementia: The Practical Basics to Know
Good luck!
Hi why am I having my third full body blood count in 6 weeks. My GP mention that my white cell reading was a little high, and was told to have another blood test, having had the results for this one, but now have been told to have another full body blood test. I am a 68yr old female. Pretty healthy. No not diabetic. Have an under active thyroid.
There’s really no way for me to say why your health provider felt it necessary to check your labs a third time. Presumably they saw something potentially concerning the first time around. I would recommend asking him or her to clarify what was abnormal, what it might mean, and what their plan is for further evaluation or possible treatment. Good luck!
You only speak to low levels of B12 being a problem for older adults. Why is there an a normal “range” for B12 from 213 to 816 if you are only concerned with low B12 values? What if a person had a reading of 1203?
In older adults such high levels of vitamin B12 would be uncommon. Also within medicine, “high” levels of vitamin B12 are not considered problematic or worrisome, presumably because we have not identified this as the sign of disease or as hazardous to the body. The lab’s “normal” range reflects what is thought to be normal for most people, but there will always be a few people who fall outside this range. If I came across such a high B12 level on a patient’s lab reports, I would probably start by asking if they are taking a supplement and if they were, advising them that there is no need to keep supplementing vitamin B12.
Dr. Andrew Weil also comments on the risks of excess vitamin B12 supplementation here: Too much B12?