Blood tests aren’t just for diagnosing illness—they’re one of the most powerful tools you have to assess your overall wellness, longevity, and functional health. When interpreted correctly, blood work offers deep insights into energy, inflammation, hormone balance, nutrient status, and metabolic resilience.

But most people only glance at whether their results are “in range” without understanding what those numbers truly mean—or what trends might be emerging beneath the surface.

This guide will walk you through how to read blood work from a wellness perspective, which markers to pay attention to, and how to advocate for deeper understanding with your healthcare provider.

The Difference Between “Normal” and “Optimal”

Standard Ranges vs. Functional Ranges

Laboratories define “normal” based on statistical averages—not on what’s best for health. These ranges often reflect a wide spectrum that includes people with chronic illnesses, sedentary lifestyles, and nutritional deficiencies. In contrast, functional ranges reflect levels associated with optimal cellular function, vitality, and disease prevention.

Vitamin D: The optimal range (75-125 nmol/L) is a narrower, higher subset of the lab normal range (50-150 nmol/L).

Ferritin: The optimal range differs for men (60-150 µg/L) and women (50-100 µg/L), both falling within the broader lab normal range (30-300 µg/L).
TSH: The functional optimal range (0.5-2.0 mIU/L) is a more specific and narrower range compared to the lab normal range (0.4-4.0 mIU/L).
CRP: The functional optimal range (<1.0 mg/L) indicates a lower target level compared to the lab normal range (<5.0 mg/L).

Functional practitioners use these tighter ranges to detect dysfunction earlier and intervene proactively.

1. Energy and Fatigue: Iron, B12, and Thyroid

Iron and Ferritin

Iron is essential for oxygen transport, cellular respiration, and ATP production. Ferritin reflects your iron reserves and is especially important for menstruating women, athletes, and anyone with chronic fatigue. Low ferritin (<30) may cause hair loss, fatigue, poor exercise tolerance, and restless legs. High ferritin may point to inflammation or metabolic syndrome.

Vitamin B12 and Folate

These B vitamins support energy production, DNA synthesis, and nervous system function. Symptoms of suboptimal B12 include fatigue, numbness or tingling, poor memory, and low mood. Functional ranges often recommend >400–500 pmol/L even though labs may list anything above 150 as “normal.”

Thyroid Hormones (TSH, Free T3, Free T4)

The thyroid controls basal metabolic rate, affecting every cell in the body. TSH should ideally fall between 0.5–2.0 mIU/L. Free T3 is the active form, and low-normal levels may still produce fatigue, weight gain, or depression. Thyroid dysfunction is often underdiagnosed due to overreliance on TSH alone.

Red Flags:

Ferritin <30 µg/L
B12 <400 pmol/L
TSH >2.5 mIU/L, especially with symptoms like low mood, cold intolerance, or weight gain

2. Inflammation and Chronic Stress

Inflammation is the root of many chronic diseases—from cardiovascular to cognitive to autoimmune. Blood markers can catch inflammation in its early, silent stages.

CRP (C-Reactive Protein)

This is a sensitive marker of systemic inflammation. CRP >3.0 mg/L may suggest low-grade inflammation due to infection, obesity, insulin resistance, or autoimmune activity. Ideally, it should be below 1.0 mg/L.

Homocysteine

An amino acid involved in methylation. Elevated levels (>10 µmol/L) may increase risk for heart disease, Alzheimer’s, and clotting disorders. It also suggests possible deficiencies in B6, B12, or folate.

WBC Count

White blood cell count provides insight into immune system activity. Elevated levels (>10) can indicate infection or chronic inflammation. Low levels (<4) may point to immune suppression or nutrient deficiency (e.g., zinc).

Supporting Markers:

Fibrinogen: Elevated in inflammation and clotting disorders
ESR: Reflects inflammatory activity, though less specific than CRP
Cortisol (AM): High levels suggest chronic stress; low levels may indicate adrenal dysfunction

3. Blood Sugar and Metabolic Health

Metabolic markers reveal how well your body handles glucose and insulin—key for preventing diabetes, cardiovascular disease, and cognitive decline.

Fasting Glucose

Ideal fasting levels are 4.5–5.3 mmol/L. Values above this, even if “normal,” may signal early insulin resistance.

HbA1c (Glycated Hemoglobin)

Reflects your average blood sugar over 2–3 months. A functional ideal is 5.0–5.4%. Anything >5.6% increases the risk for prediabetes and cardiovascular disease.

Fasting Insulin

High fasting insulin (>10 mIU/L) may appear years before blood sugar rises. This is a key early marker of metabolic stress and fat storage bias.

Additional Insight:

Triglyceride-to-HDL ratio: A ratio >2.0 may indicate insulin resistance
ALT (when elevated): Can point to non-alcoholic fatty liver linked to metabolic syndrome

4. Liver and Detoxification Markers

The liver processes toxins, hormones, and waste. Dysfunction here can silently affect energy, mood, skin, and digestion.

ALT and AST

These enzymes rise when liver cells are damaged. Slight elevations can occur from alcohol, medication, fatty liver, or viral hepatitis. ALT is more liver-specific.

GGT

Sensitive to alcohol intake, environmental toxins, and metabolic stress. Elevated GGT may also indicate oxidative stress and bile stagnation.

ALP (Alkaline Phosphatase)

While often associated with the liver, ALP also reflects bone activity. Low levels can indicate zinc or magnesium deficiency, while high levels may relate to bile flow or bone turnover.

Supporting Markers:

Bilirubin: Elevated in bile dysfunction or Gilbert’s syndrome
Albumin: Indicates liver synthetic function and nutritional status
Total Protein: Combined with albumin/globulin ratio gives insight into immune status and protein intake

5. Nutrient Status Beyond the Basics

Micronutrient levels influence immune function, mental clarity, mood, muscle function, and detox capacity.

Magnesium

Magnesium is involved in over 300 enzymatic reactions. RBC or plasma magnesium gives a better picture than serum magnesium. Low levels contribute to cramps, fatigue, anxiety, and poor sleep.

Zinc and Copper

These minerals should be in balance. Zinc supports immune health, testosterone, wound healing, and mood. Copper is necessary in small amounts but too much can be inflammatory. Ideal Zn:Cu ratio is around 1.5–2.0.

Vitamin D

Acts as a hormone, regulating immune defense, calcium metabolism, and inflammation. Optimal levels (75–125 nmol/L) are critical for mood, bone strength, and chronic disease prevention.

Omega-3 Index

Measures the EPA/DHA content in red blood cells. A value <4% suggests an inflammatory state. Aim for 8–12% for optimal brain, heart, and joint health.

6. Hormonal Clues from Standard Blood Work

While hormones like estrogen, progesterone, and testosterone require specific testing, standard panels often show indirect clues.

TSH + Free T3/T4

As discussed, thyroid hormones drive many aspects of metabolism and fertility.

CBC (Complete Blood Count)

Low hemoglobin or hematocrit may reflect iron or B12 deficiency, especially in menstruating women. A low WBC count may suggest immune suppression or adrenal stress.

Liver Enzymes and Hormone Detox

Elevated GGT or poor ALT/AST ratio may impair estrogen clearance. Poor liver detox may lead to estrogen dominance (PMS, breast tenderness, fibroids).

Total Protein and Albumin

Low protein may impair hormone transport and overall tissue repair. Often under-recognized in those on restrictive diets.

How to Take Action on Your Results

Track longitudinal trends, not just one-off results. Seeing progress or decline over time is key.
Seek functional reference ranges to interpret whether you’re thriving—not just surviving.
Work with a trained practitioner who integrates lab work into a broader picture of nutrition, lifestyle, and stress.
Use lab insights to fine-tune your plan—adjust sleep, training load, diet, supplements, and emotional wellbeing accordingly.

Final Thoughts: Blood Work as a Wellness Compass

Your blood reveals the state of your internal ecosystem—what’s working, what’s depleted, and what needs support.

When interpreted with a functional lens, blood work becomes a proactive health strategy—not just a test of what's wrong, but a map of where to go next.