Functional Lab Tests Are Everywhere. But How Many Biomarkers Do You Really Need Tested To Be Healthy?

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It may feel nearly impossible to scroll through social media these days without seeing ads for trendy, pricey functional medicine subscription services and at-home tests that promise to unlock key health insights—all from your bloodwork. These tests claim to decode your biomarkers, which are essentially data points that hint at what's going on in your body. Ordering one of these functional bloodwork panels might sound tempting if you want quick answers for hard-to-solve health problems—but not everyone needs them.
If you have a primary care provider (PCP) you're probably getting an annual standard or 'traditional' label panel at your physical that's often covered by insurance. This typically includes complete blood count (CBC), comprehensive metabolic panel (CMP), and a basic cholesterol panel, says Allie Buttarazzi, MD, an internal and lifestyle medicine physician at Maine Street Medical. 'These tests are widely used in conventional medicine and include about 30 markers in total—for example, glucose, sodium, and potassium in a CMP, or hemoglobin and white blood cells in a CBC,' she says.
Meet the experts: Allie Buttarazzi, MD, is an internal and lifestyle medicine physician at Maine Street Medical. Pooja Gidwani, MD, is a board-certified physician in internal and obesity medicine and concierge doctor focused on hormones, longevity, and weight optimization. Eleanor Yusupov, DO, is an assistant professor at New York Institute of Technology's medical school in Old Westbury, New York.
Functional lab tests, on the other hand, can include up to hundreds of biomarkers, and usually aren't covered by insurance, making them pretty pricey. 'These tests might look at hormone metabolites, nutrient levels, inflammation markers, gut microbiome diversity, or advanced cardiometabolic risk factors,' Dr. Buttarazzi says. They also include biomarkers that aren't yet supported by strong clinical evidence, so 'some results may fall into a gray zone—not necessarily harmful, but not proven helpful, either,' she adds.
Still, many people are turning to companies like Function Health and InsideTracker to optimize their health and uncover the root of their symptoms 'after traditional panels have left them feeling dismissed, confused, or without real solutions,' says Pooja Gidwani, MD, a board-certified physician in internal and obesity medicine and concierge doctor.
But do you actually need to invest in an extensive lab test on your own, or does your normal PCP's bloodwork suffice? Ahead, doctors break down which biomarkers you actually need to have tested and what to consider before paying for an expensive lab service.
Do I actually need to get a comprehensive biomarker panel done?
'It's important to perform comprehensive lab tests periodically (at least once a year) for most adults, and testing done by primary care doctors is usually sufficient for most people,' says Eleanor Yusupov, DO, an assistant professor at New York Institute of Technology's medical school in Old Westbury, New York.
The purpose of a traditional lab is just different from a functional one. 'Basic lab panels are often enough when we're screening for common, silent risk factors—like high cholesterol or early signs of metabolic disease,' Dr. Buttarazzi says. 'These standard tests are designed to catch problems that don't usually show symptoms until they're more advanced, which makes them useful for general screening.'
However, exploring other biomarkers in-depth can provide additional insight that typical tests might miss. 'Traditional panels are a great starting point, but they're often focused on detecting or preventing disease, not assertively optimizing health,' or diving further into how your biomarkers might impact your energy, cognition, sleep, and stress, Dr. Gidwani says. Traditional labs may also not be sufficient for people with specific health conditions, like heart disease, anemia, or diabetes, Dr. Yusupov adds. In these cases, you'll probably need to have your doc order more tests specific to your condition.
If you have persistent, unexplained symptoms, a unique diet or medical history, or you're simply getting older, comprehensive testing might help fill in the gaps, Dr. Buttarazzi says. 'For example, I routinely check vitamin B12, vitamin D, and iron in my patients who eat a predominantly plant-based diet. These nutrients are either less available in plant-based forms or are harder to absorb,' Dr. Buttarazzi says. She also keeps an eye on these markers in older adults since nutrient absorption naturally declines with age. 'I see comprehensive testing as a way to personalize care—not to replace evidence-based screening, but to go deeper when needed,' she says.
But if you feel fine, your annual check-up bloodwork panel will likely suffice, and there's no need to go for a more comprehensive one, especially because many of the tests offered by companies like Function Health—for example, glucose levels, calcium, kidney, liver and thyroid function tests, HIV, testing for sexually transmitted infections—are routinely recommended by primary care physicians and gynecologists anyway, says Dr. Yusupov. (However, your doctor may not automatically order those specific labs, so you have to request them—and in many cases, the patient needs to have a specific health concern for which a certain test is necessary.)
If you want extensive labs done, the key is to clarify your intention and the goal behind them—and make sure you're evaluating everything in context with a trusted provider. 'I don't recommend using programs that run hundreds of tests without understanding your history, symptoms, or goals, and especially those that don't even include a consultation,' says Dr. Gidwani. 'Without proper guidance, you end up with information overload, anxiety, and no clear next steps.'
Overall, the goal should be tailoring your labs to your body, conditions, concerns, and what insights you're hoping to gain.
Who's a good candidate for additional biomarker testing?
If you've already done traditional panels and you're still confused, frustrated, or don't have solutions for a specific health issue, you may be a good candidate for additional labs, Dr. Gidwani says. You can also benefit if you simply want to learn about your health. 'I use these panels most often for people who want to be proactive (not just reactive or preventive), those who are looking beyond symptom relief, and people aiming for prevention, performance, and longevity,' she adds.
Anyone in their 30s through 60s who wants to boost longevity
Professionals, parents, or people under chronic stress
People recovering from chronic illness or long COVID
Women in perimenopause feeling dismissed by the traditional system
People with strong family history of heart disease, diabetes, dementia, and/or autoimmune disease
Anyone dealing with vague, but persistent symptoms like fatigue, brain fog, or unexplained weight gain despite 'normal' traditional labs
People who want to protect their energy, focus, and resilience as they age
"The common thread is that these panels give us visibility into early dysfunction, help personalize interventions, and allow us to act before problems become diagnoses,' Dr. Gidwani says.
Which biomarkers are worth testing?
Again, sticking to a traditional panel at your PCP is usually fine. But if you do opt for extra labs, here are a few biomarker categories that may deliver some clinical insight:
Metabolic Health
Fasting insulin and glucose: For these, you can look at Homeostasis Model Assessment-estimated Insulin Resistance (HOMA-IR), Dr. Gidwani says. This can help detect early insulin resistance, which is one of the most important markers of aging and metabolic health.
Hemoglobin A1c (HbA1c): This represents your average blood sugar over the last 90 days, which can be used to diagnose diabetes. FYI, you can have a normal HbA1c and normal glucose, but also testing for insulin can provide more context and show if you're insulin resistant, Dr. Buttarazzi says.
Triglycerides and HDL ratio: High triglycerides can indicate insulin resistance, and your total cholesterol to HDL ratio captures cholesterol, which is another indicator of metabolic health and cardiovascular risk, Dr. Gidwani says.
Uric acid: Created when your body breaks down chemicals in food and drinks, most uric acid dissolves, passes through your kidneys, and leaves your body as urine. Too much uric acid can be related to kidney conditions and gout, per Dr. Gidwani.
Cardiovascular Risk and Lipid Particle Analysis
Apolipoprotein B: Reflects the total number of atherogenic particles, which can promote the development of plaque that blocks your arteries, per Cleveland Clinic. It's partially impacted by genetics, but it's also highly responsive to diet, exercise, and medications like statins and other meds that help lower LDL cholesterol, Dr. Gidwani says.
Apolipoprotein A1 (ApoA1): ApoA1 is the main protein carried in HDL cholesterol (the 'good' one), and measuring it can help your doctor detect your risk for heart disease. You might need this test if you know you're at risk for heart disease, or if you've already had heart problems, like a heart attack, per the University of Rochester Medical Center (URMC). Like ApoB, your ApoA1 can be influenced by genetics, exercise, and nutrition, Dr. Gidwani says.
Lipoprotein(a) or Lp(a): Lp(a) is a genetically-inherited LDL-like particle that is strongly associated with cardiovascular risk, Dr. Gidwani says. Elevated levels of Lp(a) can indicate increased risk of heart disease, but you can have high Lp(a) even if you have a healthy lifestyle, and many people don't have symptoms, per the American Heart Association (AHA). Although Lp(a) doesn't change over your lifetime and only needs to be checked once, it provides more information than a traditional lipid panel, so it's still important for people at high risk of cardiovascular disease, Dr. Yusupov says. If you have a personal family history of heart disease or known family history of high Lp(a), it may be a good idea to speak with a healthcare professional and get it checked out since it factors into your overall risk, per the AHA.
These biomarkers are also important for women who are moving from perimenopause to menopause, says Dr. Buttarazzi. 'Just that drop in estrogen is going to cause some markers to go up for the very first time.' Estrogen acts as a 'traffic controller' for helping your liver clear out 'bad' cholesterol, she says, and estrogen can also help keep Lp(a) in check—so when estrogen drops, Lp(a) levels can rise.
Inflammation and Aging Markers
High-sensitivity C-reactive protein (CRP, or hs-CRP): CRP rises when there's inflammation in the body.
Glycoprotein acetylation (GlycA): Elevated GlycA can indicate systemic inflammation.
Interleukin-6 (IL-6): This biomarker may be associated with frailty and aging, including sarcopenia (muscle loss), impaired immune function, reduced resilience to stressors like illness or surgery, and increased risk of chronic disease, Dr. Gidwani says. 'When we see persistently elevated IL-6, it may suggest that the body is in a chronic inflammatory state that contributes to vulnerability, fatigue, reduced physical capacity, and slower recovery, which are all hallmarks of frailty,' she explains.
Hormonal and Adrenal Health
Estradiol (E2), progesterone, and testosterone (free and total): These markers can offer valuable insights about hormonal health, especially during perimenopause when hormone levels are changing, says Dr. Gidwani. Estradiol (E2) gives the clearest picture of a woman's active estrogen levels, especially during their reproductive years and throughout perimenopause, Dr. Gidwani adds. Looking at testosterone and progesterone can also help explain a wide range of symptoms, from mood shifts and sleep disturbances to irregular cycles, she says.
What about fertility? The above biomarkers may offer valuable insight into fertility, but their usefulness depends heavily on timing and context, Dr. Gidwani says. For example, estradiol is typically measured early in your cycle to assess ovarian function, while progesterone is measured after ovulation. Testosterone doesn't directly determine fertility, but it may influence libido, energy, and ovulatory health, especially if you have PCOS where elevated testosterone can interfere with your cycle, she explains. That said, in perimenopausal women, estradiol and progesterone become less reliable as fertility markers, and a single lab test may not reflect true ovulatory function or ovarian reserve, Dr. Gidwani says. 'In these cases, more comprehensive testing is often needed, including anti-Müllerian hormone (AMH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and ultrasound-based antral follicle count,' she says. In particular, AMH reflects the number of remaining eggs and is one of the most consistent markers of ovarian reserve across the cycle, she says.'When interpreted together, these labs can help provide a fuller picture of reproductive health, though no single test can determine fertility on its own,' Dr. Gidwani says.
Dehydroepiandrosterone-sulfate (DHEA-S): This hormone, produced by the adrenal glands, is helpful for assessing adrenal health and stress resilience, says Dr. Gidwani.
Sex hormone binding globulin (SHBG): SHBG can influence hormone availability, Dr. Gidwani says. 'If SHBG is too high (even if your total hormone levels look normal), you may still experience symptoms of deficiency like fatigue, low libido, mood changes, or weight gain, because not enough of those hormones are free and active,' she says. Conversely, low SHBG can be associated with insulin resistance or androgen excess. 'SHBG provides essential context that allows us to interpret hormone levels accurately and tailor treatment more precisely during perimenopause or other hormone shifts,' Dr. Gidwani says.
Cortisol: This biomarker can be useful for diagnosing conditions like Cushing's syndrome (when your body has too much cortisol) and Addison's disease (not enough cortisol), per Dr. Buttarazzi. But because cortisol levels change throughout the day and several factors can influence it—like stress, physical activity, medications, and sleep—having an abnormal cortisol result doesn't necessarily mean you have a medical condition, per Cleveland Clinic. Make sure to opt for timed cortisol testing, which evaluates your cortisol rhythm throughout the day to give you a sense of the patterns that affect your energy, sleep, and recovery, Dr. Gidwani says.
Thyroid Function
Thyroid stimulating hormone (TSH): TSH is produced by your pituitary gland, and it's a standard screening marker that can give you a better sense of your thyroid health, says Dr. Gidwani. High TSH can indicate hypothyroidism and low TSH can indicate hyperthyroidism, per Cleveland Clinic.
Free T3 and Free T4: TSH alone doesn't always give you the full picture of how well your thyroid is functioning, Dr. Gidwani says—so you should also test Free T3 and Free T4 (which indicate your active thyroid hormones) to get a fuller, more detailed picture. 'Free T3 and Free T4 are the active forms of thyroid hormone that directly affect your metabolism, energy levels, mood, and cognitive function,' Dr. Gidwani says. Your 'TSH could be normal while Free T3 is low, which might explain fatigue, brain fog, or weight changes,' she says.
Reverse T3: Testing this marker can help identify hypothyroidism or stress-related suppression, Dr. Gidwani says.
TPO and TG antibodies: These are early markers of autoimmune thyroid disease, per Dr. Gidwani.
Micronutrient and Cellular Health
Vitamin D: Optimal vitamin D levels support immune function, hormonal health, bone strength, insulin sensitivity, and even mood regulation, Dr. Gidwani says—and chronically low levels have been linked to higher risk of cardiovascular disease, autoimmune conditions, metabolic syndrome, and depression. It may even help reduce risk of dementia. Checking vitamin D levels is also recommended for people with low bone mass (osteopenia or osteoporosis) and kidney disease, says Dr. Yusupov.
: This one's essential for red blood cell production and neurological health. 'Deficiency can cause fatigue, cognitive changes, and nerve symptoms like numbness, tingling, burning sensations, or even electric shock-like feelings,' says Dr. Gidwani. Checking your B12 is important for memory, energy, and it can be especially helpful for vegans (since B12 is not naturally found in plants) and people who have had weight loss surgery (who may be more susceptible to deficiency), she says.
Folate: Also known as vitamin B9, folate works with vitamin B12 and is another marker that plays a role in reducing cardiovascular risk.
Methylmalonic acid (MMA): Even if your vitamin B12 levels are normal, it doesn't always reflect whether your cells are able to use it. A methylmalonic acid (MMA) test, which indirectly measures how well vitamin B12 is working in the body, can help catch deficiency early. 'That's why MMA is especially helpful when symptoms are present but standard B12 levels look fine,' Dr. Gidwani says.
Magnesium: It supports enzymes involved in metabolism, blood sugar regulation, muscle function, and sleep, Dr. Gidwani says. More daily magnesium has also been linked to lower dementia risk. 'Deficiency can contribute to fatigue, insulin resistance, headaches, and anxiety, yet it's often missed in routine bloodwork,' she adds.
index: This biomarker is 'strongly predictive of cardiovascular and cognitive health,' says Dr. Gidwani. Low levels are associated with chronic inflammation, depression, and neurodegenerative risk, but it's easy to improve with targeted nutrition, she adds.
Iron: This essential mineral is key for the production of red blood cells. Low iron stores can affect your energy, thyroid function, and exercise capacity, Dr. Gidwani says.
Ferritin: High ferritin can reflect inflammation or hemochromatosis (known as iron overload), which can cause serious damage to your heart, liver, pancreas, and even your joints, per Cleveland Clinic.
Total iron binding capacity (TIBC): TIBC can also help diagnose iron overload and iron-deficiency anemia, per Cleveland Clinic.
So what about my biological age score? Functional labs can sometimes calculate your biological age, which supposedly tells you how 'old' you are based on your bloodwork or a saliva test. Technically, biological age results are determined by looking at telomere length (DNA at the end of a chromosome) and by examining your 'epigenetic clock'—an analysis of your DNA patterns to help you see if you're truly aging slower or faster than your chronological age suggests, Dr. Gidwani says. But many companies estimate biological age by a combination of biomarkers like blood pressure, blood sugar, cholesterol levels, heart rate, height, and weight, per Cleveland Clinic.While it sounds fun to find your biological age, the metrics are questionable since every company likely uses a different method to land on a number, per Dr. Buttarazzi. So, if this marker is included on one of your extensive lab tests, you should probably take your results with a grain of salt.
What do biomarkers really say about our health?
Biomarkers are just one piece of the puzzle, and they shouldn't be seen as the end-all, be-all for your health. Biomarkers can tell you a lot, especially when it comes to identifying dysfunction and getting personalized guidance for healthspan and longevity, Dr. Gidwani says. But doctors say it's also important to back up and look at the big picture of what might be making you feel off—like lack of sleep or other lifestyle habits that could be hindering your health.
And even the best data has its limits. Sometimes, biomarkers give us too much information that isn't relevant or that causes unnecessary worry, Dr. Gidwani says. Review results with a physician who can give you a full, holistic picture of your health—and ensure that you're on a path to long-term well-being.
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