Learn About Blood Testing

This is a master list of blood tests that should be standard for every patient. Your specific labs are determined based on symptoms and history. Most people never have all of these completed and interpreted using “functional or optimal” ranges because these are not taught in medical schools.

FUNCTIONAL OR OPTIMAL RANGES

They help identify stress in the body to prevent disease. A lab value can still fall inside the standard reference range but be outside the optimal range for your body. Rather than simply looking for disease, functional testing looks for patterns that point to root causes. Functional medicine labs help evaluate how well your body’s key systems are working before conventional markers become abnormal. - University of Chicago Medicine

STANDARD RANGES

They are based on large population averages — the main goal of these ranges is not to identify optimal health. Reference ranges are determined using a cohort of individuals who are otherwise healthy in the context of the analyte being measured. The main goal in determining reference ranges is to identify laboratory test values that distinguish between patients with and without the clinical condition being evaluated. That means once a lab value falls outside the reference range, it may indicate disease or pathology.

The total number of red blood cells per microliter of blood.
The concentration of hemoglobin (oxygen-carrying protein) in the blood.
The percentage of blood volume composed of red blood cells.
Average size of red cells.
Average hemoglobin per red cell.
Concentration of hemoglobin within RBCs.
Variation in red cell size—high variation may suggest mixed types of anemia.
Total number of white blood cells per microliter of blood. Indicates immune activity: high in infection or inflammation, low in immune suppression or bone marrow issues .
Most abundant WBC (~60–70%), frontline defenders that ingest and destroy bacteria and fungi. They’re a key part of the innate immune system.
Comprise about 20–40% of WBCs. Include B‑cells (produce antibodies), T‑cells (coordinate immunity and kill infected cells), and NK cells. Critical for adaptive immunity—recognizing past infections and targeting viruses or cancer cells
Represent ~2–8% of WBCs. Act as scavengers—eating debris and pathogens—and mature into macrophages that alert T‑cells to ongoing threats.
Make up ~1–4% of WBCs. Defend against parasites and participate in allergy and asthma responses
Least common (~0.5–1% of WBCs). Release histamine and heparin during allergic reactions and inflammation.
Number of platelets per microliter of blood. Platelets are essential for blood clotting; low levels may risk bleeding, high levels can signal clotting disorders or inflammation.
Average size of platelets. Larger platelets are younger and typically more reactive; helps assess platelet production or destruction rates.

Complete Blood Count (CBC) with Differential

The overall amount of cholesterol in your blood, encompassing LDL, HDL, and VLDL. While total cholesterol gives a general overview, it doesn't specify the types of cholesterol present.
A type of cholesterol that carries fat particles through your bloodstream. Elevated small dense LDL levels can lead to plaque buildup in arteries, increasing the risk of atherosclerosis, heart attack, and stroke. Large buoyant LDL particles are necessary and non-inflammatory. Lipid fractionation testing helps to determine types and sizes.
A type of cholesterol that helps remove LDL cholesterol from the bloodstream. Higher HDL levels are associated with a lower risk of heart disease, as it helps prevent plaque formation in arteries.
A type of fat found in the blood, derived from excess calories, alcohol, or sugar. High triglyceride levels can contribute to the hardening and narrowing of arteries, increasing the risk of cardiovascular diseases.
A type of lipoprotein that carries triglycerides in the blood. VLDL is considered a precursor to LDL and contributes to plaque buildup in arteries.
A higher ratio indicates a higher risk of heart disease. An optimal ratio is below 3.5:1, while a ratio above 5:1 suggests increased cardiovascular risk.
This ratio reflects the balance between "bad" and "good" cholesterol. A ratio above 2.5 is commonly associated with a higher risk of heart disease.
A protein found in atherogenic lipoproteins like LDL and VLDL. Elevated ApoB levels indicate a higher number of atherogenic particles, suggesting 10x increased cardiovascular risk.
A genetic variant of LDL cholesterol. High levels of Lp(a) are associated with an increased risk of heart disease, independent of other lipid measures.
Traditional lipid panels measure the concentration of cholesterol in lipoprotein particles but do not account for the number and size of these particles. Lipoprotein fractionation provides a more comprehensive view of lipid metabolism and cardiovascular risk. For instance, individuals with a high number of small, dense LDL particles may be at greater risk for cardiovascular events, even if their standard cholesterol levels are within normal ranges.
The total number of LDL particles. A higher particle number, even with normal LDL cholesterol levels, can indicate increased cardiovascular risk.
Refers to the average size of LDL particles. Smaller, denser LDL particles are more atherogenic and associated with a higher risk of cardiovascular events.
Assesses the risk of cardiovascular disease based on cholesterol health, either Pattern A or Pattern B.
The total number of HDL particles. Higher HDL-P levels are generally protective against cardiovascular disease.
The average size of HDL particles. Larger HDL particles are more effective at removing cholesterol from the bloodstream.
The total number of VLDL particles. Elevated VLDL-P levels are associated with increased triglyceride levels and higher cardiovascular risk.
The average size of VLDL particles. Larger VLDL particles are less atherogenic compared to smaller ones.

Lipid Panel

Antibodies that target structures within the cell nucleus. A positive ANA is a hallmark of many autoimmune diseases (lupus, Sjögren’s, scleroderma), but is not disease-specific.
Autoantibodies often present in rheumatoid arthritis. Elevated RF supports an RA diagnosis (seen in 60–80% of RA patients); not definitive alone

Autoimmunity Screen

For biological females, testing the hormone estradiol (one type of estrogen) is key in detecting menopause, polycystic ovarian syndrome (PCOS), androgen- or estrogen-producing tumors, uterine and breast cancer, and mitigating the risk of osteoporosis and cardiovascular disease. If one is on hormonal birth control, this test will not be run.
When SHBG levels change, it can impact the amount of available hormones in the body, either too much or too little. This can affect the menstrual cycle as well as fertility. SHBG patrols the amount of sex hormones the body tissues can use.
LH levels give insight into sexual development and fertility. LH releases estrogen during the menstrual cycle, which triggers the release of an egg from the ovary, otherwise known as ovulation. It can also help determine states of perimenopause and menopause. If one is on hormonal birth control, this test will not be run.
FSH evaluates ovarian health and pituitary function, and can help determine a diagnosis of polycystic ovary syndrome (PCOS), perimenopause, or menopause. As a type of protein hormone, FSH is responsible for stimulating the ovarian follicles that produce and release eggs during ovulation. If one is on hormonal birth control, this test will not be run.
DHEA Sulfate, the most abundant hormone in the human body, is associated with longevity, positive reproductive outcomes, and immune system regulation. This test can gauge reproductive function and the health of your adrenal gland.
Prolactin levels can guide the diagnosis of irregular or absent menstrual periods, infertility, menopausal symptoms, osteoporosis, liver or kidney disease, hypothyroidism, and/or estrogen and testosterone deficiency, in addition to unwanted lactation. It is also used to screen for pituitary tumors. Prolactin is a peptide hormone produced by the pituitary gland and stimulates breast development and milk production in pregnant women.
This helps evaluate functions associated with testosterone levels, such as fertility, sexual function, muscle mass, energy, mood, insulin resistance/sensitivity, and pituitary function. It can also detect prediabetes, PCOS, or menopause. Function tests both "free" and “total” testosterone in the blood.
In all adults, healthy levels of testosterone are important for general health, body composition, sexual function, and reduced risk of disease. Function tests both "free" and “total” testosterone in your blood. One will naturally have a higher level of "total" than "free.”
IGF-1 is known as the "growth hormone" because it stimulates growth in cells throughout the body. This leads to growth and development (from the womb and through adolescence), strengthening of tissues (e.g. improving bone density, building muscle), and healing (e.g. skin, bones, gut lining), depending on what the body needs.

Female Hormones

A hormone from the pituitary gland (not a thyroid hormone!) that controls thyroid activity by signaling it to produce T3 and T4.
The unbound portion of T4 available to tissues. Reflects thyroid production capacity.
A type of cholesterol that helps remove LDL cholesterol from the bloodstream. Higher HDL levels are associated with a lower risk of heart disease, as it helps prevent plaque formation in arteries.
The active thyroid hormone; only a small portion is unbound and usable.
Measures both bound and free T3 hormones.
An inactive form of T3 produced when T4 is converted “off-pathway.” Elevated rT3 may block active T3 and reflect conversion issues caused by stress or illness.
Autoantibodies against thyroid peroxidase, an enzyme essential for hormone production. High levels indicate autoimmune reactions like Hashimoto’s or Graves’ disease; present in ~90% of Hashimoto’s cases.
Autoantibodies targeting thyroglobulin, a thyroid hormone precursor. Typically elevated in Hashimoto’s.
TSI are antibodies that overstimulate the thyroid gland commonly linked to autoimmune hyperthyroidism such as Graves' disease.
A critical building block for thyroid hormones T₄ and T₃ (T₄ contains four iodine atoms, T₃ contains three). Deficiency can lead to goiter, hypothyroidism, developmental delays, and brain impairment. Found in iodized salt, seafood, dairy, and seaweed.
Integral to selenoproteins (e.g., glutathione peroxidase and deiodinases) that protect thyroid cells from oxidative stress and enable conversion of T₄ to active T₃. Found in Brazil nuts, seafood, eggs, and organ meats.

Thyroid Panel

Insulin levels can uncover reasons behind abnormal blood sugar, insulin resistance, and more. It can also reveal hidden blood sugar issues even years before they escalate to something like diabetes. Establishing one's insulin baseline can be incredibly insightful to how one's lifestyle affects health.
HbA1c is the average amount of glucose attached to blood cells over the last 90 days. It diagnoses, monitors, and screens for prediabetes and diabetes. This test is a revelatory look into one's health, specifically the body’s ability to control blood sugar. Unhealthy levels are triggered by inflammation, vitamin deficiencies, kidney damage, thyroid disorders, and more. One's diet and habits can have a substantial impact on this test.
Uric acid in the blood screens for metabolic disorders, like gout, anemia, and immunodeficiencies. This often overlooked test has renewed attention after recent studies show elevated levels can increase the risk of death from cardiovascular issues by 39% and stroke by 35%.
C-peptide reflects how much insulin the pancreas is producing providing key insights into the body's management of blood sugar. It's particularly useful for distinguishing between types of diabetes and identifying insulin resistance.

Blood Sugar

Ferritin levels can help diagnose iron deficiency, liver disease, inflammation, or insulin resistance. Ferritin is a protein that stores iron in cells and then releases the iron when the body makes more red blood cells.
A homocysteine test checks the body’s vitamin B levels and methylation function, a key biochemical process essential for almost all of the body’s systems. Abnormal homocysteine can build up and increase the risk of blood clots, dementia, osteoporosis, heart disease, heart attack, and stroke. Homocysteine is an amino acid that helps organs grow and regenerate.
Healthy iron levels create vitality throughout the entire body. Iron helps various vital functions, like providing energy and focus, building a strong gastrointestinal tract and immune system, and regulating body temperature. Iron deficiency can lead to numerous biological problems, including anemia.
TIBC assesses the body’s ability to transport iron in the blood, and can diagnose and/or monitor iron-deficiency or iron overload. Lower than normal levels of TIBC could indicate too much iron and a variety of conditions, including anemias, inflammation, or liver disease.
The Iron % Saturation test measures the percentage of transferrin, a protein that transports iron in the blood, that is saturated with iron. This test is crucial for assessing iron status in the body and can help diagnose conditions such as iron deficiency anemia or iron overload disorders like hemochromatosis.
Magnesium is a mineral imperative for cells to make energy, for chemical pumps to work and stabilize membranes, and to help muscles relax. Low magnesium can impact calcium, potassium, phosphorus, and/or parathyroid hormone. This test helps evaluate absorption and helps determine whether or not there’s a problem with kidney function or the gastrointestinal tract.
Vitamin D deficiency is widely underdiagnosed and undertreated. Over time, low levels can lead to hypothyroidism, osteoporosis, cancer, heart disease, fatigue, depression, seasonal affective disorder (SAD), gut issues, and fibromyalgia. The role of vitamin D is vast and benefits the immune system, thyroid, bones and teeth, muscles, and brain.
Vitamin B12 is integral for nerve function, DNA synthesis, and red blood cell formation. Testing helps identify deficiencies linked to fatigue, neurological symptoms, and anemia.

Nutrients

When SHBG levels change, it can impact the amount of available hormones in the body, either too much or too little. This can affect the menstrual cycle as well as fertility. SHBG patrols the amount of sex hormones the body tissues can use.
DHEA-S can gauge the health of the reproductive system and adrenal glands. It is one of three adrenal androgens: steroid hormones that control the development and maintenance of masculine characteristics.
This helps evaluate functions associated with testosterone levels, such as fertility, sexual function, muscle mass, energy, mood, insulin resistance/sensitivity, and pituitary function. It can also screen for prediabetes. Function tests both "free" and “total” testosterone in the blood.
In all adults, healthy levels of testosterone are important for general health, body composition, sexual function, and reduced risk of disease.

Male Hormones

The primary energy molecule for your cells. High fasting levels may indicate prediabetes or diabetes.
A vital mineral mostly stored in bones, also critical for nerve, muscle, and heart function. Abnormal levels can affect bone health, nerve and heart function, or indicate parathyroid issues.
Regulated by kidneys; essential for fluid balance and nerve signaling.
Crucial for muscle contractions and heart rhythm.
Works with sodium to manage body fluid and acid-base balance.
Reflects acid-base (pH) balance.
Waste product from protein breakdown; elevated in kidney dysfunction or dehydration.
Calculated from creatinine levels, age, gender, and ethnicity. It estimates kidney function; a lower GFR indicates reduced kidney efficiency.
Muscle metabolism byproduct cleared by kidneys; elevated levels can indicate impaired kidney function.
A liver-made protein that transports hormones, drugs, and maintains fluid balance.
A byproduct of red blood cell breakdown processed by the liver. High bilirubin levels can cause jaundice (yellowing of the skin and eyes) and may indicate liver dysfunction, bile duct obstruction, or hemolysis .
Sum of albumin plus globulins (e.g., antibodies); assesses nutritional and immune status.
An enzyme found in various tissues, including the liver, bones, kidneys, and bile ducts.
An enzyme primarily found in the liver. ALT is more liver-specific than AST. High ALT levels typically indicate liver cell injury or inflammation, such as in hepatitis or fatty liver disease .
An enzyme found in the liver, heart, muscles, and kidneys. Elevated AST levels can indicate liver damage; however, since AST is also present in other tissues, high levels may also suggest muscle or heart issues .
An enzyme found in the liver and bile ducts. Elevated GGT levels can indicate liver disease, bile duct problems, or alcohol use. It's often used to confirm that an elevated ALP is due to liver or bile duct issues .

Complete Metabolic Panel (CMP)

hs-CRP is revelatory in one's overall health as it relates to the risk of inflammation-related diseases. Chronic inflammation is linked to every major disease: heart disease (even before symptoms occur), type 2 diabetes, cancer, high blood pressure, Alzheimer’s, depression, all autoimmune diseases, and severe allergic reactions like asthma.
ESR measures inflammation in the body and is often elevated in autoimmune conditions like rheumatoid arthritis lupus and vasculitis.