How to Read Your Blood Test Results

Secure Draw
Jun 23
2 min read

Getting your blood test results back and seeing rows of numbers, abbreviations, and flags can feel overwhelming. This guide breaks down the most common values, what they measure, and how to understand what your lab report is telling you.

How Lab Reports Are Structured

Most lab reports show three things for each test: your result, the reference range (what is considered normal), and a flag (H for high, L for low) if your value falls outside the range. A flag does not always mean something is wrong. Context matters, and your doctor interprets results in light of your full health picture.

Common Blood Test Values Explained

CBC (Complete Blood Count)

WBC (white blood cells): measures immune cells. High can indicate infection or inflammation. Low can signal immune suppression.
RBC (red blood cells): carries oxygen. Low RBC is a common marker of anemia.
Hemoglobin and hematocrit: related measures of oxygen-carrying capacity. Low values suggest anemia.
Platelets: involved in clotting. Very high or very low values warrant follow-up.

CMP (Comprehensive Metabolic Panel)

Glucose: blood sugar level. Elevated fasting glucose may indicate prediabetes or diabetes.
BUN and creatinine: kidney function markers. Elevated levels can signal reduced kidney function.
ALT and AST: liver enzymes. Elevated levels may indicate liver stress or damage.
Sodium, potassium, calcium: electrolytes essential for many body functions. Imbalances can have various causes.

Lipid Panel

Total cholesterol: overall cholesterol level. Under 200 mg/dL is generally desirable.
LDL (bad cholesterol): lower is better for heart health.
HDL (good cholesterol): higher is better.
Triglycerides: blood fats. Under 150 mg/dL is normal.

Thyroid (TSH)

TSH tells you how hard your pituitary gland is working to stimulate the thyroid. High TSH typically suggests the thyroid is underactive (hypothyroidism). Low TSH suggests it is overactive (hyperthyroidism).

When to Call Your Doctor

Call your doctor if you receive results with significant flags, especially for kidney function, liver enzymes, blood sugar, or CBC values outside the normal range. A single out-of-range result is not always cause for alarm, but your doctor should interpret it in context.

Frequently Asked Questions

What does H or L mean on my lab report?

H means your result is above the reference range. L means it is below. Neither automatically means something is seriously wrong. Your doctor interprets these in context.

Are reference ranges the same for everyone?

No. Reference ranges can vary by age, sex, and the laboratory that processed your sample. Always compare your result to the range shown on your specific report.

Should I be worried if one value is slightly out of range?

Not necessarily. Mild variations are common and often not clinically significant. Your doctor will advise whether follow-up is needed.

Get Your Labs Done at Home

Ready to book your at-home blood draw? Secure Draw Mobile serves Santa Monica, Venice, Brentwood, Westwood, Culver City, and West Los Angeles. Appointments available Monday through Friday 6 AM to 3 PM and Saturday 6 to 10 AM. Book online at securedrawmobile.com or call (310) 893-1693.