How to read your own lab results
You are legally entitled to your own medical records, including lab results, under HIPAA. Most labs and health systems now send results directly to patients through patient portals, often before your doctor has reviewed them. Reading them yourself isn't overstepping — it's your health. Here's what the common tests actually mean.
The reference range
Every lab result comes with a reference range — the values considered normal for that test. These ranges are typically derived from a population of healthy adults, representing the middle 95%. That means 5% of healthy people fall outside the reference range.
Being slightly outside the reference range doesn't automatically mean something is wrong. Context matters: your trend over time, your symptoms, your other values, your specific situation. A single out-of-range value is a data point, not a diagnosis.
Complete Blood Count (CBC)
The CBC measures the cellular components of your blood.
WBC (White Blood Cell Count)
- Normal: ~4.5–11.0 × 10³/µL
- High: infection, inflammation, stress response, some medications, rarely leukemia
- Low: viral infections, some medications (especially chemotherapy), autoimmune conditions, bone marrow issues
RBC (Red Blood Cell Count) + Hemoglobin + Hematocrit These three travel together and all measure variations of "how much oxygen-carrying capacity does your blood have."
- Low: anemia (iron, B12, or folate deficiency are most common causes)
- High: dehydration, chronic low oxygen exposure (altitude, smoking), rarely polycythemia vera
MCV (Mean Corpuscular Volume) — average size of red blood cells
- High (large cells): B12 or folate deficiency, alcohol use, liver disease
- Low (small cells): iron deficiency anemia, thalassemia
Platelets
- Normal: 150,000–400,000/µL
- Low: clotting risk, can be caused by medications, infections, or bone marrow issues
- High: inflammation, iron deficiency, rarely a blood disorder
Comprehensive Metabolic Panel (CMP)
The CMP checks kidney function, liver function, blood sugar, and electrolytes.
Glucose
- Fasting normal: 70–99 mg/dL
- 100–125: prediabetes
- 126+: diabetes (if confirmed on repeat testing)
BUN (Blood Urea Nitrogen) + Creatinine Both measure kidney function. Elevated together suggests the kidneys aren't filtering properly. BUN also rises with dehydration or high protein intake. Creatinine is more specific to kidney function.
eGFR (estimated Glomerular Filtration Rate) This one actually tells you how well your kidneys are working as a percentage of normal function.
- Over 60: typically normal range
- 45–59: mild to moderate decrease
- Below 30: significant kidney disease
Liver enzymes: ALT and AST
- Normal: under ~40 U/L for both (varies by lab)
- Mildly elevated: exercise (especially AST), fatty liver, alcohol, medications
- Significantly elevated: liver inflammation, damage, or disease
Sodium, Potassium, Chloride, CO2 These electrolytes regulate fluid balance and nerve/muscle function. Significant derangements are serious; mild variations often reflect hydration status or labs taken incorrectly.
Calcium
- Normal: 8.5–10.5 mg/dL
- Elevated: dehydration, hyperparathyroidism, certain cancers — worth following up if persistently high
Lipid Panel
LDL ("bad" cholesterol)
- The number most associated with cardiovascular risk
- Optimal: under 100 mg/dL
- Borderline high: 130–159
- High: 160+
- Very high: 190+
- Note: optimal LDL depends on your overall risk profile — for someone who's had a heart attack, doctors aim for under 70
HDL ("good" cholesterol)
- Higher is better
- Low HDL (under 40 for men, under 50 for women) is an independent cardiovascular risk factor
Triglycerides
- Normal: under 150 mg/dL
- Elevated: diet heavy in refined carbs and sugar, alcohol, diabetes, hypothyroidism
Total cholesterol Less useful alone than the breakdown — a high total can be driven by high HDL, which is actually good.
Thyroid (TSH)
TSH (Thyroid Stimulating Hormone) is typically the first thyroid test ordered.
- Normal: approximately 0.4–4.0 mIU/L (varies by lab)
- High TSH: your pituitary is working harder to stimulate an underactive thyroid (hypothyroidism)
- Low TSH: your pituitary is pulling back because thyroid hormone is too high (hyperthyroidism or too much medication)
TSH is counterintuitive — a high result means low thyroid function, not high.
A1C
The A1C measures your average blood sugar over the previous 2–3 months.
- Under 5.7%: normal
- 5.7–6.4%: prediabetes
- 6.5%+: diabetes
A single fasting glucose can be affected by what you ate yesterday. A1C shows the pattern.
Things to know before panicking
- Slightly out of range ≠ disease. Reference ranges catch 95% of healthy people. Some healthy people are in the 5% that falls outside.
- Labs vary. Different labs use different reference ranges. Your result might be flagged by one lab but not another.
- Context is everything. A mildly elevated creatinine means something different in a 25-year-old vs. a 70-year-old with diabetes.
- Trends matter more than single values. Creatinine of 1.3 that's been stable for three years is different from creatinine of 1.3 that was 0.8 six months ago.
- Ask your doctor what they're tracking. If something is flagged, ask: is this something we're monitoring, or something we need to act on now?
Quick reference
- You are entitled to your results under HIPAA — request them if your portal doesn't auto-share
- Reference ranges = middle 95% of healthy adults; outside it ≠ automatically sick
- CBC = blood cells; CMP = kidneys, liver, sugar, electrolytes
- Lipid panel = LDL/HDL/triglycerides; A1C = 3-month blood sugar average
- TSH high = underactive thyroid (counterintuitive)
- Trend and context matter more than a single result