Comprehensive Blood Work Interpretation — Functional vs Standard Ranges

Blood work is the foundation of clinical assessment. But the way most practitioners read labs leaves enormous blind spots. Standard reference ranges are built from population averages — they tell you whether someone is statistically “normal,” not whether they are physiologically optimal. A fasting glucose of 99 mg/dL is “normal” by standard criteria, but functionally it signals insulin resistance already in motion. A ferritin of 15 ng/mL is “within range” but represents iron depletion that has been building for months.

Functional blood chemistry analysis reads the same labs through a tighter lens. It asks: where does this person sit on the spectrum between disease and optimal function? And critically, it reads markers in relationship to each other — not in isolation.

Complete Blood Count (CBC)

The CBC is the most ordered and most under-read panel in medicine. It reveals immune status, oxygen-carrying capacity, nutritional deficiencies, bone marrow function, and chronic inflammation — if you know how to read the patterns.

White Blood Cells (WBC) and Differential

WBC Total

• Standard range: 4.5–11.0 x10^3/uL
• Optimal functional range: 5.0–7.5 x10^3/uL

A WBC below 5.0 suggests immune suppression — possible viral burden (chronic EBV, CMV), zinc deficiency, or bone marrow depression. Above 7.5 without acute illness points to chronic low-grade inflammation, hidden infection, or cortisol-driven immune activation.

Neutrophils (40–60% of WBC, absolute 1.8–7.0) The first responders. Elevated neutrophils (neutrophilia) suggest bacterial infection, acute stress, or corticosteroid use. Low neutrophils (neutropenia) raise concern for viral suppression, autoimmunity, or certain medications.

Lymphocytes (20–40% of WBC, absolute 1.0–3.5) The adaptive immune army — T cells, B cells, NK cells. Elevated lymphocytes suggest viral infection (EBV, CMV, hepatitis), chronic immune activation, or lymphoproliferative disorders. Low lymphocytes raise concern for immune exhaustion, HIV, cortisol excess, or zinc deficiency.

The Neutrophil-to-Lymphocyte Ratio (NLR): Optimal is 1.0–2.0. An NLR above 3.0 is a systemic inflammation marker associated with cardiovascular risk, cancer prognosis, and chronic stress physiology. This single ratio often tells more than either value alone.

Monocytes (4–8%) Elevated monocytes suggest chronic infection, tissue damage and repair, or recovery phase from acute illness. Persistently elevated monocytes warrant investigation for chronic inflammatory conditions.

Eosinophils (1–3%, absolute 0–0.5) The parasite and allergy cells. Elevated eosinophils (>3% or absolute >0.5) signal parasitic infection, allergic response (asthma, eczema, food allergy), or eosinophilic GI disease. In functional medicine, elevated eosinophils in someone with GI symptoms should trigger investigation for parasites (GI-MAP) and food sensitivities.

Basophils (0–1%) The rarest WBC. Elevated basophils suggest allergic or hypersensitivity reactions, hypothyroidism, or myeloproliferative disorders. Functionally, persistent basophilia with histamine symptoms points toward mast cell activation or histamine intolerance — cross-reference with DAO enzyme status.

Red Blood Cells and Oxygen Carrying Capacity

RBC Count

• Standard: 4.0–5.5 x10^6/uL (men), 3.5–5.0 (women)
• Optimal: 4.5–5.0 (men), 4.0–4.5 (women)

Hemoglobin

• Standard: 12.0–16.0 g/dL (women), 13.5–17.5 (men)
• Optimal: 13.5–14.5 (women), 14.5–15.5 (men)

Hematocrit

• Standard: 36–46% (women), 40–54% (men)
• Optimal: 37–42% (women), 42–48% (men)

Low hemoglobin and hematocrit define anemia, but the type of anemia is determined by the red cell indices below.

Red Cell Indices — The Anemia Detective Kit

MCV (Mean Corpuscular Volume) — the size of your red blood cells.

• Standard: 80–100 fL
• Optimal: 85–92 fL

This is one of the most clinically useful numbers on the CBC.

• Microcytic (MCV < 80): Small red cells. Iron deficiency anemia is the most common cause. Also consider thalassemia trait (especially in Mediterranean, Southeast Asian, African descent — check iron studies and hemoglobin electrophoresis), chronic disease anemia, or copper deficiency.
• Macrocytic (MCV > 100): Large red cells. B12 deficiency, folate deficiency, or both. Also seen with hypothyroidism, liver disease, excess alcohol, certain medications (metformin depletes B12, PPIs impair B12 absorption). An MCV of 95–100 is a gray zone — functionally, this is already trending toward B12/folate insufficiency.
• Normocytic (MCV 80–100): Normal-sized cells but still anemic? Think chronic disease, early iron deficiency (before MCV drops), kidney disease (low erythropoietin), or acute blood loss.

MCH (Mean Corpuscular Hemoglobin): 27–33 pg (optimal 28–32). Tracks with MCV — low MCH with low MCV = iron deficiency pattern.

MCHC (Mean Corpuscular Hemoglobin Concentration): 32–36 g/dL (optimal 33–35). Low MCHC = hypochromic cells, iron deficiency. Elevated MCHC is rare but seen in spherocytosis.

RDW (Red Cell Distribution Width): Standard <14.5%. Optimal <13%. RDW measures variation in red cell size. An elevated RDW (>13%) is one of the earliest markers of nutrient deficiency — iron, B12, or folate depletion shows up here before MCV changes. RDW >13% is also an independent risk factor for cardiovascular mortality and correlates with systemic inflammation.

Platelets

• Standard: 150–400 x10^3/uL
• Optimal: 200–300 x10^3/uL

Low platelets (<150): immune thrombocytopenia (ITP), viral infections (hepatitis C, HIV, EBV), liver disease (reduced thrombopoietin), medications, autoimmune conditions, or splenic sequestration. Functionally, platelets between 150–200 warrant monitoring.

High platelets (>400): reactive thrombocytosis from inflammation, infection, iron deficiency (the body upregulates platelets when iron is low — cross-reference with ferritin), or primary myeloproliferative disorders.

Comprehensive Metabolic Panel (CMP)

Glucose and Kidney Markers

Fasting Glucose

• Standard: 65–99 mg/dL
• Optimal: 75–86 mg/dL

A fasting glucose of 90–99 is “normal” by standard criteria but represents prediabetic physiology. Functional practitioners flag anything above 86 as early insulin resistance. Always cross-reference with fasting insulin (optimal 3–8 uIU/mL) and hemoglobin A1c (optimal 4.8–5.2%). A glucose of 82 with an insulin of 15 is worse than a glucose of 92 with an insulin of 5 — the pancreas is working overtime to maintain that “normal” glucose.

BUN (Blood Urea Nitrogen)

• Standard: 7–25 mg/dL
• Optimal: 13–18 mg/dL

BUN reflects protein metabolism and kidney function. Low BUN (<13) suggests insufficient protein intake, malabsorption, or liver dysfunction (liver converts ammonia to urea). High BUN (>18) without kidney disease suggests dehydration, excessive protein intake, GI bleeding (digested blood = protein load), or catabolic states.

Creatinine

• Standard: 0.6–1.3 mg/dL
• Optimal: 0.8–1.1 mg/dL

A product of muscle metabolism and a measure of kidney filtration (GFR). Very low creatinine in a non-elderly person may indicate low muscle mass. Rising creatinine warrants kidney function investigation.

BUN/Creatinine Ratio

• Optimal: 10:1 to 16:1

A ratio >16:1 suggests dehydration, high protein intake, or upper GI bleeding. A ratio <10:1 suggests low protein intake, liver disease, or overhydration. This ratio is an underappreciated clinical tool.

Electrolytes

Sodium (standard 135–145, optimal 138–142 mEq/L): Low sodium — SIADH, diuretics, adrenal insufficiency, excess water intake. High sodium — dehydration, Cushing’s, diabetes insipidus.

Potassium (standard 3.5–5.0, optimal 4.0–4.5 mEq/L): Critical for cardiac rhythm. Low potassium — diuretics, vomiting/diarrhea, aldosterone excess, magnesium deficiency (you cannot correct potassium without correcting magnesium). High potassium — kidney disease, ACE inhibitors, metabolic acidosis.

Chloride (standard 96–106, optimal 100–106 mEq/L): Tracks inversely with bicarbonate. Elevated chloride with low CO2 suggests metabolic acidosis.

CO2/Bicarbonate (standard 21–32, optimal 25–30 mEq/L): Low CO2 (<25) suggests metabolic acidosis — could be from ketosis, lactic acidosis, renal tubular acidosis, or chronic diarrhea. Functionally, low CO2 with fatigue and elevated anion gap raises concern for mitochondrial dysfunction.

Anion Gap (standard 8–16, optimal 10–14): Calculated as Na - (Cl + CO2). Elevated anion gap suggests unmeasured acids — lactic acid, ketoacids, uremic toxins, toxin ingestion (methanol, ethylene glycol, salicylates).

Calcium, Albumin, and Protein Status

Calcium (Total)

• Standard: 8.5–10.5 mg/dL
• Optimal: 9.2–10.0 mg/dL

Total calcium must always be interpreted alongside albumin. For every 1 g/dL albumin below 4.0, add 0.8 mg/dL to the calcium (corrected calcium). Persistent calcium above 10.2 with elevated PTH = primary hyperparathyroidism. Low calcium — check vitamin D, magnesium (needed for PTH function), and phosphorus.

Albumin

• Standard: 3.5–5.5 g/dL
• Optimal: 4.0–5.0 g/dL

Albumin below 4.0 is a red flag. It reflects nutritional status (protein intake), liver synthetic function, chronic inflammation (albumin is a negative acute phase reactant — it drops when inflammation rises), or protein-losing conditions (nephrotic syndrome, protein-losing enteropathy). Albumin below 3.5 independently predicts mortality in hospitalized patients.

Total Protein (standard 6.0–8.0, optimal 6.9–7.4 g/dL): High total protein with normal albumin = elevated globulins (immune activation, chronic infection, autoimmunity, multiple myeloma).

Globulin (standard 2.0–3.5, optimal 2.4–2.8 g/dL): Elevated globulin suggests chronic immune stimulation. Low globulin suggests immune deficiency.

A/G Ratio (optimal 1.5–2.0): Low A/G ratio = immune activation or liver disease.

Liver Enzymes — The Hepatic Dashboard

AST (Aspartate Aminotransferase)

• Standard: 10–40 U/L
• Optimal: 10–25 U/L

ALT (Alanine Aminotransferase)

• Standard: 7–56 U/L
• Optimal: 10–25 U/L

The pattern matters more than individual values:

• ALT > AST: Non-alcoholic fatty liver disease (NAFLD), metabolic syndrome, hepatitis. This is the most common pattern in functional medicine populations.
• AST > ALT (ratio > 2:1): Alcoholic liver disease, cirrhosis, or muscle damage (AST is also in skeletal and cardiac muscle — check CK if AST is elevated alone).
• Both mildly elevated (25–40) with normal standard range: Functionally significant. This is subclinical hepatic stress — evaluate for NAFLD (check triglycerides, fasting insulin, GGT), medication burden, or chronic viral hepatitis.

ALP (Alkaline Phosphatase) (standard 44–147, optimal 50–85 U/L): Elevated ALP with elevated GGT = hepatobiliary origin (bile duct obstruction, cholestasis). Elevated ALP with normal GGT = bone origin (Paget’s disease, hyperparathyroidism, bone metastases, growth in adolescents). Low ALP (<50) suggests zinc deficiency (zinc is a cofactor for ALP) or malnutrition.

GGT (Gamma-Glutamyl Transferase) (standard 9–48, optimal 10–25 U/L): The most sensitive liver enzyme. Elevated GGT before other liver enzymes rise signals early hepatic stress, oxidative stress, or glutathione depletion. GGT is induced by alcohol, medications, and environmental toxins. It is also an independent cardiovascular risk marker.

Bilirubin (Total) (standard 0.1–1.2, optimal 0.3–0.9 mg/dL): Mildly elevated bilirubin (1.0–2.5) in an otherwise healthy person is often Gilbert’s syndrome — a benign UGT1A1 polymorphism affecting bilirubin conjugation, present in ~5–10% of the population. Bilirubin is actually a potent antioxidant; mild elevation may be protective.

Iron Panel — The Full Picture

Never rely on ferritin alone. A complete iron panel includes:

Serum Iron (standard 60–170, optimal 85–130 mcg/dL): Fluctuates with meals and time of day. Best measured fasting, morning.

TIBC (Total Iron Binding Capacity) (standard 250–370, optimal 275–350 mcg/dL): High TIBC = iron deficiency (the body makes more transferrin to grab scarce iron). Low TIBC = iron overload, chronic disease, or liver disease.

Transferrin Saturation (% Sat) (standard 15–50%, optimal 25–35%): Below 20% = iron deficiency even if ferritin is “normal.” Above 45% = iron overload risk (investigate hemochromatosis — HFE gene).

Ferritin

• Standard: 12–150 ng/mL (women), 12–300 (men)
• Optimal: 70–100 ng/mL (women), 100–150 ng/mL (men)

Ferritin is the most misinterpreted marker in medicine. A ferritin of 15 is “normal” by standard range but represents iron depletion — this person has fatigue, hair loss, restless legs, and brain fog. Ferritin must reach 50+ before hair regrows and 70+ for optimal energy and cognitive function.

But ferritin is also an acute phase reactant. It rises with inflammation, infection, liver disease, and malignancy. A ferritin of 300 in an inflamed person may mask true iron deficiency — check TIBC and transferrin saturation to distinguish. If ferritin is elevated but transferrin saturation is low, inflammation is driving ferritin up while iron stores are actually depleted.

Lipid Panel — Beyond Total Cholesterol

Total Cholesterol (standard <200, functional context: 180–240 may be appropriate depending on age and context): Total cholesterol below 160 is associated with increased mortality, depression, and cancer risk. Cholesterol is the precursor to all steroid hormones, vitamin D, and bile acids.

LDL Cholesterol (standard <100, optimal depends on particle size and inflammation): Standard LDL is calculated (Friedewald equation), not measured. It does not distinguish between large buoyant LDL (pattern A — benign) and small dense LDL (pattern B — atherogenic). Advanced lipid testing (NMR LipoProfile, Cardio IQ) measures LDL particle number (LDL-P), which is a far better cardiovascular risk predictor.

HDL Cholesterol (standard >40 men, >50 women, optimal >55 men, >65 women): HDL below 40 is a cardiovascular risk factor. Very high HDL (>90) is not always protective — dysfunctional HDL exists. Cross-reference with hs-CRP and triglycerides.

Triglycerides (standard <150, optimal <80 mg/dL): Triglycerides are the best blood marker of carbohydrate and sugar intake. Fasting triglycerides above 100 suggest insulin resistance, especially when paired with low HDL.

TG/HDL Ratio — the single most useful lipid ratio:

• Optimal: <1.0
• Acceptable: 1.0–2.0
• High risk: >2.0 (strongly correlates with insulin resistance and small dense LDL)

VLDL (optimal <15 mg/dL): VLDL carries triglycerides. Elevated VLDL reflects hepatic overproduction of triglyceride-rich particles — driven by excess carbohydrates, alcohol, and insulin resistance.

Inflammatory Markers

hs-CRP (High-Sensitivity C-Reactive Protein)

• Standard: <3.0 mg/L
• Optimal: <1.0 mg/L
• Cardiovascular risk: <1.0 = low, 1.0–3.0 = moderate, >3.0 = high

CRP is produced by the liver in response to IL-6. It reflects systemic inflammation. Causes of elevated hs-CRP: visceral obesity, periodontal disease, chronic infection, gut permeability, autoimmunity, metabolic syndrome, sleep apnea. An hs-CRP above 1.0 should trigger investigation — this is not a marker to watch passively.

ESR (Erythrocyte Sedimentation Rate) (standard 0–20 men, 0–30 women, optimal <10): ESR rises with inflammation, infection, and autoimmune conditions. It is slower to rise and slower to normalize than CRP, making it useful for tracking chronic inflammatory conditions.

Homocysteine (standard 5–15 umol/L, optimal 6–8 umol/L): Homocysteine above 8 is a cardiovascular risk factor, a marker of impaired methylation, and indicates B12, folate, and/or B6 insufficiency. Elevated homocysteine damages endothelial lining, promotes clotting, and is neurotoxic. MTHFR polymorphisms are a common driver. Treatment: methylfolate, methylcobalamin, P5P (active B6), riboflavin, TMG (trimethylglycine/betaine).

Uric Acid (standard 3.0–7.0 men, 2.5–6.0 women, optimal 3.5–5.5): Uric acid above 5.5 is a marker for metabolic syndrome, insulin resistance, cardiovascular disease, and kidney disease — not just gout. Fructose metabolism is a primary driver of uric acid elevation. Uric acid below 3.0 may indicate molybdenum deficiency or oxidative stress (uric acid is also an antioxidant).

Reading the Whole Picture — The Functional Blood Chemistry Audit

Individual markers mean little in isolation. Functional blood chemistry is pattern recognition:

• Iron deficiency pattern: Low ferritin, low serum iron, high TIBC, low transferrin saturation, low MCV, low MCH, elevated RDW, possibly elevated platelets.
• B12/folate deficiency pattern: High MCV, high MCH, elevated homocysteine, low B12 (or low-normal — below 500 pg/mL is functionally insufficient), elevated methylmalonic acid (MMA — specific for B12 vs folate).
• Insulin resistance pattern: Fasting glucose >86, fasting insulin >8, TG/HDL ratio >2.0, elevated uric acid, low HDL, elevated ALT, elevated GGT, hs-CRP >1.0, elevated ferritin (as acute phase reactant), low SHBG.
• Chronic inflammation pattern: Elevated hs-CRP, elevated ESR, elevated ferritin (with normal or low iron saturation), low albumin, elevated globulin, elevated WBC (>7.5), elevated RDW, elevated platelets.
• Liver stress pattern: ALT > AST with elevated GGT, elevated triglycerides, elevated uric acid, elevated fasting insulin — think NAFLD. AST > ALT with elevated GGT — think alcohol or advanced liver disease.
• Adrenal/stress pattern: Low-normal WBC with relative lymphocytosis (cortisol suppresses lymphocytes — so high cortisol shifts toward neutrophilia; low cortisol permits lymphocyte dominance), low sodium, elevated potassium, low glucose, low albumin.

The functional medicine blood chemistry audit reads 50–70 markers simultaneously, mapping them against each other. No single marker makes a diagnosis. The pattern tells the story. The body speaks in constellations, not individual stars.