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Medical Science
Grade 10-12
Common Blood Tests Reference Cheat Sheet
A printable reference covering CBC values, CMP values, lab report ranges, abnormal flags, and interpretation patterns for grades 10-12.
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Common blood tests help clinicians screen for infection, anemia, dehydration, organ function problems, and electrolyte imbalance. This cheat sheet summarizes the most common parts of a complete blood count, comprehensive metabolic panel, and basic lab report. Students need it because lab names, units, and reference ranges can be hard to remember. The goal is to support science learning, not to diagnose disease.
Key Facts
- A CBC includes white blood cells, red blood cells, hemoglobin, hematocrit, platelets, and often a white blood cell differential.
- A typical adult white blood cell count is about 4,000 to 11,000 cells per microliter, and high values can be linked with infection, inflammation, or stress.
- A typical adult hemoglobin range is about 12 to 16 g/dL for many females and 13.5 to 17.5 g/dL for many males, and low hemoglobin may suggest anemia.
- A typical adult platelet count is about 150,000 to 450,000 platelets per microliter, and platelets are needed for normal blood clotting.
- A CMP commonly includes glucose, calcium, sodium, potassium, chloride, CO2, BUN, creatinine, albumin, total protein, bilirubin, ALP, ALT, and AST.
- A typical fasting blood glucose range is about 70 to 99 mg/dL, while values of 126 mg/dL or higher on repeat fasting tests can suggest diabetes.
- Kidney function is often checked using BUN and creatinine, with a typical adult creatinine range near 0.6 to 1.3 mg/dL depending on age, sex, and muscle mass.
- Lab interpretation should compare the result to the listed reference range, check the unit, look for H or L flags, and consider patterns across related tests.
Vocabulary
- CBC
- A complete blood count is a blood test that measures blood cells, including red blood cells, white blood cells, and platelets.
- CMP
- A comprehensive metabolic panel is a group of blood tests that gives information about electrolytes, kidney function, liver function, proteins, and glucose.
- Reference range
- A reference range is the span of values expected for many healthy people, but it can vary by age, sex, lab method, and medical context.
- Hemoglobin
- Hemoglobin is the oxygen-carrying protein in red blood cells that helps move oxygen from the lungs to body tissues.
- Electrolyte
- An electrolyte is a charged mineral in body fluids, such as sodium, potassium, chloride, or bicarbonate, that helps control fluid balance and nerve and muscle function.
- Abnormal flag
- An abnormal flag is a lab report marker, often H or L, showing that a result is above or below that lab's reference range.
Common Mistakes to Avoid
- Treating one abnormal value as a diagnosis is wrong because many results can change from hydration, recent meals, exercise, stress, medications, or lab variation.
- Ignoring the units is wrong because the same test can be reported in different units, and a number only has meaning when matched to its unit.
- Using one universal normal range is wrong because reference ranges can differ by lab, age, sex, pregnancy status, and measurement method.
- Reading CBC and CMP results separately without looking for patterns is wrong because related tests often explain each other, such as low hemoglobin with low hematocrit or high BUN with high creatinine.
- Assuming H always means dangerous and L always means harmless is wrong because the size of the change, symptoms, medical history, and related results determine how important a result is.
Practice Questions
- 1 A lab report lists sodium as 132 mmol/L, and the reference range is 135 to 145 mmol/L. Is the sodium low, normal, or high?
- 2 A student has a white blood cell count of 13,200 cells per microliter, and the reference range is 4,000 to 11,000 cells per microliter. What abnormal flag would likely appear, and what are two possible non-diagnostic reasons it might be elevated?
- 3 A CMP shows fasting glucose of 92 mg/dL, potassium of 5.7 mmol/L with a reference range of 3.5 to 5.0 mmol/L, and creatinine of 0.9 mg/dL. Which value is outside the listed range?
- 4 Why should a clinician look at patterns across multiple CBC or CMP results instead of interpreting one test value by itself?