The Complete Blood Panel: Functional Medicine Interpretation

Why Standard Ranges Are the Problem

A standard lab report tells you whether you’re dying. A functional medicine interpretation tells you whether you’re thriving. The difference between the two is the distance between a “normal” fasting glucose of 99 mg/dL (one point from prediabetes) and an optimal 82 mg/dL. That 17-point gap is a decade of metabolic drift that conventional medicine will ignore until it becomes full-blown disease.

Standard reference ranges are derived from population averages — populations that are overweight, inflamed, medicated, and metabolically broken. Being “normal” in a sick population is not health. It is shared dysfunction.

This guide covers both the Complete Blood Count (CBC) and the Comprehensive Metabolic Panel (CMP) — the two panels ordered in virtually every blood draw. Together, they reveal the status of your immune system, red blood cell health, liver function, kidney function, blood sugar regulation, electrolyte balance, and protein metabolism. But only if you know what to look for.

Complete Blood Count (CBC)

White Blood Cells: Your Immune Army

Total WBC: 4.5-6.5 x10^3/uL optimal (standard range 4.0-11.0)

Think of WBC as the standing army. Too many soldiers on the field means there is a war happening — infection, chronic inflammation, stress, autoimmune attack, or rarely leukemia. Too few soldiers means the army is depleted — chronic viral infections (EBV, CMV), bone marrow suppression, autoimmune destruction, nutrient deficiency (copper, zinc, folate, B12), or medication side effects.

A WBC of 10.5 is “normal” by standard criteria. It is not normal. It is an immune system on high alert.

The Differential: Which Troops Are Deployed

The differential tells you which branch of the immune military is active:

Neutrophils (40-60%): The infantry — first responders to bacterial infection. Elevated neutrophils (neutrophilia) point to bacterial infection, acute stress, corticosteroid use, or smoking. Low neutrophils (neutropenia) suggest viral infection, medication toxicity (chemotherapy, certain antibiotics), autoimmune neutropenia, or copper/B12 deficiency.

Lymphocytes (25-40%): The intelligence corps — viral defense and adaptive immunity. Elevated lymphocytes suggest active viral infection (EBV, CMV, hepatitis), chronic infection, or lymphoproliferative disorders. Low lymphocytes signal cortisol excess (chronic stress), HIV, autoimmune disease, or zinc deficiency.

Monocytes (4-8%): The cleanup crew — become macrophages in tissue. Elevated monocytes suggest chronic inflammation, recovery phase of infection, or autoimmune disease. They are the bridge between innate and adaptive immunity.

Eosinophils (1-3%): The parasite hunters and allergy responders. Elevated eosinophils (>3%) scream parasitic infection, allergic reaction, food sensitivity, eczema, asthma, or eosinophilic esophagitis. This is a marker I always check in patients with unexplained GI symptoms or chronic allergies.

Basophils (0-1%): The histamine bombs. Elevated basophils are rare but can indicate allergic inflammation, myeloproliferative disease, or hypothyroidism.

The Neutrophil-to-Lymphocyte Ratio (NLR)

NLR: <2.0 optimal

This is one of the most powerful yet underused markers in medicine. Divide absolute neutrophils by absolute lymphocytes. An NLR above 3.0 is a validated marker of systemic inflammation, and research links it to cardiovascular risk, cancer prognosis, mortality in COVID-19, and surgical outcomes. An NLR above 5.0 is a red flag demanding investigation.

The NLR captures what CRP sometimes misses: the balance between innate (neutrophil) and adaptive (lymphocyte) immunity. Chronic stress drives NLR up through cortisol — cortisol raises neutrophils and suppresses lymphocytes simultaneously.

Red Blood Cells: Oxygen Delivery System

RBC: 4.2-4.9 x10^6/uL (women), 4.5-5.5 (men) Hemoglobin: 13.5-14.5 g/dL (women), 14.5-15.5 (men) optimal Hematocrit: 37-44% (women), 40-48% (men)

These three markers travel together. When all three drop, you are anemic — your tissues are starving for oxygen. But functional medicine catches the drift long before outright anemia. A hemoglobin of 12.1 in a woman is “normal” but already reflects suboptimal iron stores, resulting in fatigue, brain fog, exercise intolerance, and hair loss.

MCV: The Red Blood Cell Size Detective

MCV: 85-92 fL optimal

MCV (Mean Corpuscular Volume) tells you the size of your red blood cells, and size reveals the underlying nutritional deficiency:

• MCV <85 fL (microcytic): Small red blood cells. Think iron deficiency first, then B6 deficiency, thalassemia trait, chronic disease, and rarely lead poisoning. Iron deficiency is the most common nutrient deficiency worldwide.
• MCV >92 fL (macrocytic): Large red blood cells. Think B12 deficiency, folate deficiency, hypothyroidism, liver disease, alcohol use, or medications (metformin depletes B12; methotrexate depletes folate).
• MCV 85-92 fL: The sweet spot — properly nourished red blood cells.

A critical subtlety: MCV can be falsely normal when iron deficiency and B12 deficiency coexist. The small cells and large cells average out to a normal-looking MCV while two deficiencies rage underneath.

MCH, MCHC, and the Crucial RDW

MCH (Mean Corpuscular Hemoglobin): 28-32 pg — how much hemoglobin per red blood cell. Low MCH mirrors low MCV in iron deficiency.

MCHC (Mean Corpuscular Hemoglobin Concentration): 32-36 g/dL — hemoglobin concentration within each cell. Low MCHC confirms iron deficiency. Elevated MCHC suggests hereditary spherocytosis.

RDW (Red Cell Distribution Width): <13% optimal (standard allows up to 14.5%)

RDW is the hidden gem. It measures variation in red blood cell size. Even when MCV looks perfectly normal, an RDW above 13% tells you something is wrong — emerging nutrient deficiency, mixed deficiency, chronic inflammation, or early bone marrow dysfunction. Studies link elevated RDW to cardiovascular mortality, even independent of anemia. This is a canary in the coal mine.

Platelets: The Clotting and Inflammation Nexus

Platelets: 200-250 x10^3/uL optimal (standard 150-400)

Platelets are not just about clotting. They are inflammatory mediators.

• High platelets (thrombocytosis): Reactive causes include iron deficiency (the body compensates), chronic inflammation, infection, post-splenectomy, and malignancy. Iron deficiency is the most common cause of elevated platelets in young women — check ferritin.
• Low platelets (thrombocytopenia): Autoimmune (ITP), viral infections (hepatitis C, HIV, EBV), medications, liver disease with portal hypertension (spleen sequesters platelets), B12/folate deficiency, or bone marrow failure.

Mean Platelet Volume (MPV): 8-10 fL — larger platelets are younger and more reactive. Elevated MPV suggests platelet destruction (the bone marrow pumps out bigger, younger replacements) and correlates with cardiovascular risk.

Comprehensive Metabolic Panel (CMP)

Glucose: Catching the Drift Early

Fasting glucose: 75-86 mg/dL optimal

The standard cutoff of <100 mg/dL allows a fasting glucose of 99 to be called “normal.” It is not normal. Insulin resistance develops 10-15 years before glucose rises above 100. A fasting glucose of 92 mg/dL already suggests the pancreas is working overtime to keep glucose controlled. Pair with fasting insulin (<5 uIU/mL optimal) and HbA1c (4.8-5.2% optimal) to catch metabolic dysfunction a decade before diabetes diagnosis.

BUN and Creatinine: Kidney and Protein Status

BUN: 13-18 mg/dL optimal

Blood Urea Nitrogen reflects protein metabolism and kidney function. Low BUN (<10) suggests inadequate protein intake, poor digestion (low stomach acid, pancreatic insufficiency), or liver dysfunction (the liver converts ammonia to urea). High BUN (>20) suggests dehydration, excessive protein intake, kidney dysfunction, GI bleeding (digested blood is a protein load), or catabolic state.

Creatinine: 0.8-1.2 mg/dL optimal — a byproduct of muscle creatine metabolism filtered by kidneys. Elevated creatinine is a late marker of kidney damage. Very low creatinine in a non-muscular person may suggest low muscle mass or sarcopenia.

BUN/Creatinine ratio: 13-17 optimal. High ratio (>20) with normal creatinine = dehydration, GI bleeding, or high protein diet. Low ratio (<10) = liver disease, malnutrition, or overhydration.

eGFR (estimated Glomerular Filtration Rate): >90 mL/min optimal. Below 60 is chronic kidney disease Stage 3. The equation uses creatinine, age, sex, and race. Note: muscular individuals may have falsely low eGFR from higher creatinine production.

Electrolytes: The Electrical System

Sodium: 137-142 mEq/L — low sodium (hyponatremia) causes confusion, fatigue, seizures. Common with SIADH, adrenal insufficiency, diuretics, excessive water intake. High sodium = dehydration.

Potassium: 4.0-4.5 mEq/L — critical for heart rhythm and muscle function. Low potassium from diuretics, vomiting, diarrhea, insulin excess, or low magnesium (must fix magnesium first — potassium will not correct without adequate magnesium). High potassium = kidney disease, ACE inhibitors, hemolyzed sample (false positive).

Chloride: 100-106 mEq/L — moves inversely with bicarbonate. Low chloride suggests metabolic alkalosis (vomiting). High chloride suggests metabolic acidosis or dehydration.

CO2 (Bicarbonate): 23-28 mEq/L — acid-base buffer. Low CO2 = metabolic acidosis (ketoacidosis, renal tubular acidosis, chronic diarrhea). High CO2 = metabolic alkalosis (vomiting, diuretics) or respiratory compensation.

Calcium: Always Correct for Albumin

Total calcium: 9.4-10.0 mg/dL optimal

Nearly half of blood calcium is bound to albumin. If albumin is low, total calcium looks falsely low. The corrected calcium formula: add 0.8 mg/dL for every 1.0 g/dL albumin below 4.0. Elevated calcium (hypercalcemia) in an outpatient is primary hyperparathyroidism until proven otherwise. Low calcium: check vitamin D, magnesium (needed for PTH function), and parathyroid status.

Liver Enzymes: The Metabolic Factory Report

AST (SGOT): <25 U/L optimal — found in liver, heart, muscle, and red blood cells. Elevated AST is not liver-specific; it rises with intense exercise, muscle damage, and hemolysis. AST also requires B6 (pyridoxal phosphate) as a cofactor — very low AST (<10) can indicate B6 deficiency.

ALT (SGPT): <25 U/L optimal — more liver-specific than AST. ALT >25 suggests fatty liver (NAFLD), hepatitis, medication toxicity, or alcohol. The AST:ALT ratio matters: >2:1 suggests alcoholic liver disease; <1 suggests NAFLD.

ALP (Alkaline Phosphatase): 50-75 U/L optimal — from liver and bone. High ALP: biliary obstruction, bone disease (Paget’s, fracture healing, growing children), or vitamin D excess. Low ALP (<50): zinc deficiency — ALP is a zinc-dependent enzyme. Persistently low ALP should trigger zinc testing.

GGT (Gamma-Glutamyl Transferase): <20 U/L optimal — the most sensitive liver enzyme. Elevated GGT without elevated ALP is a marker of glutathione depletion, oxidative stress, and toxin exposure (alcohol, medications, environmental toxins). GGT above 30 is an independent cardiovascular risk factor. This enzyme deserves far more attention than it receives.

Bilirubin (total): 0.5-1.0 mg/dL optimal — the breakdown product of hemoglobin. Mildly elevated bilirubin (1.0-3.0) with normal liver enzymes is often Gilbert’s syndrome — a benign genetic variant (UGT1A1 polymorphism) affecting 5-10% of the population. Here is the paradox: the mild hyperbilirubinemia of Gilbert’s is actually protective. Bilirubin is a potent antioxidant. People with Gilbert’s have lower rates of cardiovascular disease and cancer. Low bilirubin (<0.5) may indicate increased oxidative stress.

Total Protein, Albumin, Globulin: Protein Economy

Total protein: 6.8-7.4 g/dL optimal Albumin: 4.0-5.0 g/dL optimal — the most abundant serum protein, made by the liver. Low albumin (<3.5) is a powerful predictor of morbidity and mortality — from malnutrition, liver disease, chronic inflammation (albumin is a negative acute phase reactant — it drops when inflammation rises), or protein-losing nephropathy/enteropathy.

Globulin: 2.2-2.8 g/dL optimal — includes immunoglobulins. High globulin suggests chronic infection, autoimmune disease, liver disease, or myeloma. Low globulin suggests immune deficiency.

A/G ratio (Albumin/Globulin): 1.5-2.0 optimal — a low A/G ratio reflects either liver dysfunction (low albumin production) or immune activation (high globulin production). This ratio is an underappreciated screening tool for chronic inflammation and immune dysregulation.

The Integrative View

Never read a blood panel in isolation. Patterns tell stories that individual markers cannot:

• Low WBC + low RBC + low platelets = pancytopenia — bone marrow issue, severe B12 deficiency, or autoimmune destruction
• High glucose + high triglycerides + low HDL = metabolic syndrome — insulin resistance is the root
• Low BUN + low albumin + low total protein = protein malnutrition or liver failure
• High MCV + low WBC + high LDH + high bilirubin = megaloblastic anemia with hemolysis — B12 or folate emergency
• Low ALP + high MCV + low WBC = zinc deficiency + B12 deficiency — commonly seen together in vegetarians and the elderly

The blood panel is a photograph of your biochemistry at one moment in time. But read correctly, it reveals the trajectory — whether you are building health or quietly drifting toward disease. The functional medicine interpretation catches the drift years before the diagnosis, when reversal is still simple and complete.