General

Total Cholesterol measures the sum of all cholesterol types in the blood (LDL-C, HDL-C, VLDL-C etc.). While historically used, its significance in isolation is limited compared to specific lipoprotein fractions like ApoB, LDL-P, or Non-HDL-C, especially for longevity goals. It provides a very broad overview but isn't a primary target for optimization, as risk is driven by the number of atherogenic particles (ApoB). E.g., a TC of 180 mg/dL could be optimal (HDL 85, non-HDL 95) or poor (HDL 35, non-HDL 145). Use within/outside standard reference range.

High-Density Lipoprotein Cholesterol (HDL-C), often termed "good" cholesterol, measures the amount of cholesterol carried by HDL particles. HDL is involved in reverse cholesterol transport, moving cholesterol away from arteries. While higher levels are generally correlated with lower cardiovascular risk, the functionality of HDL particles is also critical, not just the cholesterol quantity. Optimal levels are generally considered >50 mg/dL, but extremely high levels may not offer further benefit and the focus is shifting towards HDL function and particle characteristics.

Triglycerides (TG) are a type of fat (lipid) found in the blood, primarily carried by VLDL particles. Elevated fasting triglycerides are a marker of metabolic dysfunction, often linked to insulin resistance, high carbohydrate intake, and increased cardiovascular risk. Optimal levels are generally considered much lower than standard guidelines, ideally <100 mg/dL, and potentially even <75 mg/dL for peak metabolic health and longevity. Note: Results are less reliable if not measured in a fasted state (8-12 hours).

Low-Density Lipoprotein Cholesterol (LDL-C), often called "bad" cholesterol, measures the cholesterol content within LDL particles. While a standard marker for cardiovascular risk, it can sometimes be discordant with particle number (ApoB or LDL-P). High LDL-C contributes to atherosclerosis. For longevity and aggressive risk reduction, optimal targets are often set much lower than standard guidelines. Ranges assume no underlying medical conditions such as prior heart disease (in which case, targets like <55 mg/dL may be appropriate).

Total Cholesterol to HDL-C Ratio provides insight into cardiovascular risk by comparing total cholesterol to protective HDL levels. A lower ratio is generally considered better. While less emphasized than ApoB or Non-HDL-C, it can offer additional perspective, especially when HDL levels are very low or very high.

Non-HDL Cholesterol is calculated as Total Cholesterol minus HDL-C. It represents the cholesterol content in all potentially atherogenic lipoproteins (LDL, VLDL, IDL, Lp(a)). It serves as a good surrogate marker for ApoB when direct measurement isn't available. Lower levels are better for cardiovascular health, with optimal targets for longevity often set significantly below standard guidelines (e.g., <100 mg/dL or even <80 mg/dL).

Blood Urea Nitrogen (BUN) measures the amount of nitrogen in the blood that comes from urea, a waste product formed in the liver from protein metabolism and excreted by the kidneys. Elevated BUN can indicate decreased kidney function, dehydration, high protein intake, or gastrointestinal bleeding. Low BUN is less common but can occur with liver disease or malnutrition. Often interpreted alongside creatinine (BUN/Creatinine ratio).

Serum Creatinine is a waste product generated from muscle metabolism (creatine breakdown). It is filtered out of the blood by the kidneys, so blood levels are a key indicator of kidney filtration function when considered alongside factors like age, sex, race, and muscle mass. Higher levels generally indicate poorer kidney function. Use eGFR (Estimated Glomerular Filtration Rate) calculated from Creatinine for a better assessment of kidney function.

BUN/Creatinine Ratio compares blood urea nitrogen to creatinine levels. An elevated ratio (>20:1) often suggests pre-renal causes of kidney injury (like dehydration or decreased blood flow to kidneys), GI bleeding, or high protein intake, as BUN rises disproportionately to creatinine. A low ratio (<10:1) might indicate liver disease (low urea production) or low protein intake.

Serum Sodium is the main cation in extracellular fluid and crucial for maintaining fluid balance, nerve impulse transmission, and muscle function. Levels are tightly regulated by the kidneys and hormones. Abnormal levels (hyponatremia or hypernatremia) usually reflect disturbances in water balance rather than sodium intake, often related to kidney function, hormonal issues (like ADH), or excessive fluid loss/gain.

Serum Potassium is the primary intracellular cation, essential for nerve conduction, muscle contraction (especially the heart), and fluid balance. Serum levels are kept within a narrow range, primarily regulated by the kidneys. Abnormal levels (hypokalemia or hyperkalemia) can cause serious cardiac arrhythmias and muscle weakness, resulting from kidney disease, medications (diuretics, ACE inhibitors), hormonal issues, or severe fluid loss.

Serum Chloride is the major anion in extracellular fluid, working with sodium to maintain fluid balance and acid-base status. Levels often mirror sodium levels. Abnormal chloride levels can result from dehydration, kidney disease, excessive vomiting or diarrhea, or acid-base disturbances (like metabolic acidosis or alkalosis).

Total Carbon Dioxide (CO2) content in serum primarily reflects the level of bicarbonate (HCO3-), a major component of the body's acid-base buffering system managed by the kidneys and lungs. Abnormal levels indicate acid-base imbalances: low levels suggest metabolic acidosis or respiratory alkalosis, while high levels suggest metabolic alkalosis or respiratory acidosis.

Serum Calcium measures the total amount of calcium (bound to albumin and free/ionized) in the blood. Calcium is essential for bone health, muscle contraction, nerve signaling, and blood clotting. Levels are tightly regulated by parathyroid hormone (PTH) and vitamin D. Abnormal levels can indicate issues with the parathyroid glands, vitamin D status, kidney function, or certain cancers. Ionized calcium is the biologically active form and may be more accurate if albumin is abnormal.

Total Protein measures the combined concentration of all proteins in the blood serum, primarily albumin and globulins. It provides a general indication of nutritional status, liver function (protein synthesis), kidney function (protein loss), and hydration. Abnormal levels usually prompt investigation of specific protein fractions (albumin, globulin types).

Serum Albumin is the most abundant protein in the blood, synthesized by the liver. It maintains oncotic pressure (keeping fluid in blood vessels), transports hormones, fatty acids, and drugs, and acts as an antioxidant and anti-inflammatory mediator. Low levels can indicate liver disease, kidney disease (loss in urine), malnutrition, chronic inflammation, or infection (negative acute phase reactant). High levels usually suggest dehydration.

Serum Globulin is a calculated value (Total Protein - Albumin) representing a diverse group of proteins, including immunoglobulins (antibodies) and carrier proteins. Elevated globulins can indicate chronic inflammation, infection, autoimmune diseases, or certain blood cancers (like multiple myeloma). Low levels are less common but might occur with immunodeficiency or protein loss. The Albumin/Globulin ratio (A/G Ratio) is often considered, with optimal > 1.5.

Albumin/Globulin Ratio is a calculated value (Albumin / Globulin) representing the ratio of albumin to globulin in the blood. It is often used to assess liver function and inflammation.

Total Bilirubin measures the sum of direct (conjugated) and indirect (unconjugated) bilirubin in the blood. Bilirubin is a yellowish pigment produced from the breakdown of heme (mostly from red blood cells). Elevated levels cause jaundice (yellowing of skin/eyes) and can indicate liver disease (impaired conjugation/excretion), bile duct obstruction, or increased RBC breakdown (hemolysis). Gilbert's syndrome is a common, benign cause of mild unconjugated hyperbilirubinemia.

Alkaline Phosphatase (ALP) is an enzyme found primarily in the liver (bile ducts), bone, intestines, and placenta. Elevated levels can indicate liver disease (especially cholestatic conditions affecting bile flow), bone disorders with increased bone turnover (e.g., Paget's disease, fractures, growing children, vitamin D deficiency), or, rarely, other causes. Isoenzyme testing can help determine the source (liver vs. bone).

Aspartate Aminotransferase (AST) is an enzyme found primarily in the liver, heart, skeletal muscle, and kidneys. Elevated serum AST levels often indicate liver cell damage (hepatitis, toxins, ischemia) but can also rise due to muscle injury (including heart attack) or hemolysis. Its interpretation requires context, often alongside ALT (ALT is more liver-specific).

Alanine Aminotransferase (ALT) is an enzyme found predominantly in liver cells. Elevated serum ALT is a more specific indicator of liver cell injury or inflammation (hepatitis, fatty liver disease, drug toxicity) than AST. Consistently maintaining ALT in the lower end of the reference range is associated with better liver health.

Thyroid-Stimulating Hormone (TSH), produced by the pituitary gland, regulates thyroid hormone production. High TSH suggests hypothyroidism (underactive thyroid), while low TSH suggests hyperthyroidism (overactive thyroid). While standard ranges are broad (e.g., ~0.4-4.5 mIU/L), many longevity and functional medicine experts advocate for a narrower optimal range for better overall well-being, even in the absence of overt disease. Note: In elderly individuals (e.g., >70-80 years old), TSH may naturally be slightly higher (e.g., up to 5-7 mIU/L) without necessarily indicating pathology or requiring treatment.

25-Hydroxy Vitamin D [25(OH)D] is the primary circulating form of vitamin D and the best measure of overall vitamin D status. Vitamin D is crucial for calcium absorption, bone health, immune function, and cellular regulation. Deficiency is widespread and linked to various health issues.

Hemoglobin A1c (HbA1c) reflects average blood glucose levels over the preceding 2-3 months by measuring the percentage of hemoglobin protein in red blood cells that has glucose attached (glycated). It's a key marker for diagnosing and monitoring diabetes risk. While valuable, HbA1c is an average and doesn't capture glucose variability or spikes; Continuous Glucose Monitoring (CGM) provides a more comprehensive view of glycemic control. Standard Interpretation:

• < 5.7%: Normal
• 5.7% - 6.4%: Prediabetes
• ≥ 6.5%: Diabetes For optimal health and minimizing glycation-related damage associated with aging, longevity experts often target levels below the prediabetes threshold, ideally <5.5% or even <5.3%.

White Blood Cell (WBC) Count, also known as leukocyte count, measures the total number of white blood cells in the blood. These cells are key components of the immune system. Elevated levels (leukocytosis) often indicate infection, inflammation, or stress, while low levels (leukopenia) can result from bone marrow issues, certain infections, or medications, increasing susceptibility to infection.

Red Blood Cell (RBC) Count measures the number of red blood cells per volume of blood. RBCs contain hemoglobin and are responsible for transporting oxygen from the lungs to the tissues. Low RBC count (anemia) reduces oxygen-carrying capacity, while high count (polycythemia or erythrocytosis) increases blood viscosity.

Hemoglobin (Hgb) is the protein within red blood cells that binds to and carries oxygen. Measuring hemoglobin concentration is a primary test for anemia (low Hgb) or polycythemia/erythrocytosis (high Hgb). Anemia leads to fatigue and reduced exercise capacity due to impaired oxygen delivery.

Hematocrit (Hct), also known as Packed Cell Volume (PCV), measures the percentage of blood volume occupied by red blood cells. It generally correlates with hemoglobin and RBC count and is used to assess anemia or polycythemia/erythrocytosis. Dehydration can falsely elevate hematocrit.

Mean Corpuscular Volume (MCV) measures the average size (volume) of red blood cells. It is crucial for classifying anemia: low MCV (<80 fL) indicates microcytic anemia (e.g., iron deficiency, thalassemia), normal MCV (80-100 fL) indicates normocytic anemia (e.g., chronic disease, acute blood loss), and high MCV (>100 fL) indicates macrocytic anemia (e.g., B12/folate deficiency, liver disease, alcohol excess).

Mean Corpuscular Hemoglobin (MCH) measures the average amount (weight) of hemoglobin within a single red blood cell. It tends to correlate with MCV; smaller cells (low MCV) generally have less hemoglobin (low MCH), and larger cells (high MCV) have more. Low MCH (<27 pg) (hypochromia) is typical in iron deficiency anemia and thalassemia.

Mean Corpuscular Hemoglobin Concentration (MCHC) measures the average concentration of hemoglobin within red blood cells (relative to cell volume). Low MCHC (<32 g/dL) indicates hypochromia (paler cells), seen in iron deficiency and thalassemia. High MCHC (>36 g/dL) is less common but can occur in conditions like spherocytosis or due to artifact (e.g., cold agglutinins, lipemia).

Red Cell Distribution Width (RDW or RDW-CV) measures the variation in the size of red blood cells (anisocytosis), reported as a percentage coefficient of variation. A high RDW indicates a large variation in cell sizes, commonly seen early in iron deficiency anemia (mix of small and normal cells) and B12/folate deficiency (mix of large and normal cells), often before MCV changes. Consistently low RDW (<13%) is generally considered optimal, indicating uniform cell size.

Platelet Count measures the number of platelets (thrombocytes) per volume of blood. Platelets are small cell fragments crucial for blood clotting (hemostasis). Low platelet count (thrombocytopenia) increases bleeding risk, while high count (thrombocytosis) can increase clotting risk and may indicate inflammation, infection, iron deficiency, or underlying myeloproliferative disorders.

Mean Platelet Volume (MPV) measures the average size of platelets in the blood. Younger platelets released from the bone marrow are typically larger. High MPV can indicate increased platelet production and turnover, sometimes seen with inflammation, recovery from thrombocytopenia, or certain genetic conditions. Low MPV might suggest impaired platelet production (e.g., aplastic anemia). Interpretation often combined with platelet count and PDW.

Absolute Neutrophil Count (ANC) measures the total number of neutrophils per volume of blood (WBC count x Neutrophil %). It provides a direct measure of the body's primary defense against bacterial infections. Low ANC (neutropenia, especially <1000 or <500 cells/uL) significantly increases infection risk, often seen after chemotherapy or with certain disorders. High ANC (neutrophilia) typically indicates infection or inflammation.

Absolute Lymphocyte Count (ALC) measures the total number of lymphocytes (T cells, B cells, NK cells) per volume of blood (WBC count x Lymphocyte %). Low ALC (lymphopenia, <1000 cells/uL) can indicate viral infections (like HIV, COVID-19), immune deficiencies, malnutrition, or stress (high cortisol), and is associated with increased mortality risk. High ALC (lymphocytosis) is common in viral infections (like mono) or certain leukemias/lymphomas.

Absolute Eosinophil Count (AEC) measures the total number of eosinophils per volume of blood (WBC count x Eosinophil %). High AEC (eosinophilia, typically >500 cells/uL) is a key indicator of allergic reactions (asthma, eczema, hay fever), parasitic infections, certain skin disorders, drug reactions, or rarer eosinophilic syndromes.

Absolute Basophil Count (ABC) measures the total number of basophils per volume of blood (WBC count x Basophil %). Basophils are the least common granulocyte. Elevated ABC (basophilia) is relatively rare but can be associated with allergic reactions, chronic inflammation, hypothyroidism, or myeloproliferative disorders like CML.

Neutrophils Percentage represents the proportion of neutrophils among all white blood cells in a differential count. Neutrophils are the most abundant type of WBC and are primary responders to bacterial infections. Increased percentage (relative neutrophilia) suggests infection or inflammation, while decreased percentage (relative neutropenia) might be seen with increases in other cell types like lymphocytes.

Eosinophils Percentage indicates the proportion of eosinophils in the WBC differential. Eosinophils are involved in fighting parasitic infections and modulating allergic inflammatory responses. Increased percentage (eosinophilia) is commonly associated with allergies, asthma, parasitic infections, and certain skin or inflammatory disorders.

Basophils Percentage represents the proportion of basophils, the least common type of granulocyte. They contain histamine and heparin and are involved in allergic reactions and inflammatory responses. Increased percentage (basophilia) is uncommon but can be seen in allergic reactions, chronic inflammation, hypothyroidism, or certain blood disorders (like CML).