What Do Blood Tests Show?
Blood tests show whether the levels of different
substances in your blood fall within a normal range.
For many blood substances, the normal range is the
range of levels seen in 95 percent of healthy people in a particular group. For
many tests, normal ranges are different depending on your age, gender, race,
and other factors.
Many factors can cause your blood test levels to
fall outside the normal range. Abnormal levels may be a sign of a disorder or
disease. Other factors—such as diet, menstrual cycle, how much physical
activity you do, how much alcohol you drink, and the medicines you take (both
prescription and over-the-counter)—also can cause abnormal levels.
Your doctor should discuss any unusual or abnormal
blood tests results with you. These results may or may not suggest a health
problem.
Many diseases or medical problems can’t be
diagnosed with blood tests alone. However, they can help you and your doctor
learn more about your health. Blood tests also can help find potential problems
early, when treatments or lifestyle changes may work best.
Result Ranges for Common Blood Tests
This section presents the result ranges for some of
the most common blood tests.
NOTE: All values in this section are for adults
only. They don’t apply to children. Talk to your child’s doctor about
values on blood tests for children.
Complete Blood Count
The table below shows some normal ranges for
different components of the complete blood count (CBC). Some of the normal
ranges are different for men and women. Other factors, such as age and race,
also may affect normal ranges.
Your doctor should discuss your results with you. He
or she will advise you further if your results are outside the normal range for
your group.
|
Test |
Normal Range Results* |
| Red blood cell (varies
with altitude) |
Male: 5 to 6 million
cells/mcL
Female: 4 to 5 million cells/mcL |
| White
blood cell |
4,500 to 10,000
cells/mcL |
| Platelets
|
140,000 to 450,000
cells/mcL |
| Hemoglobin (varies with
altitude) |
Male: 14 to 17 gm/dL
Female: 12 to 15 gm/dL |
| Hematocrit (varies with
altitude) |
Male: 41 to 50%
Female: 36 to 44% |
| Mean
corpuscular volume |
80 to 95
femtoliter |
* Cells/mcL = cells per microliter; gm/dL
= grams per deciliter
Blood Glucose
This table shows the ranges for blood glucose levels
after 8 to 12 hours of fasting (not eating). It shows the normal range and also
the abnormal ranges that are a sign of prediabetes or diabetes.
|
Plasma Glucose Results (mg/dL)*
|
Diagnosis |
| 99 and below |
Normal |
| 100 to 125 |
Prediabetes |
| 126 and above |
Diabetes† |
* mg/dL = milligrams per deciliter.
† The test is repeated on another day to confirm the results.
Lipoprotein Panel
The table below shows ranges for total cholesterol,
LDL ("bad") cholesterol, and HDL ("good") cholesterol levels after 9 to 12
hours of fasting.
High
blood cholesterol is a risk factor for
coronary
heart disease.
Your doctor should discuss your results with you. He
or she will advise you further if your results are outside the desirable range.
|
Total Cholesterol
Level |
Total Cholesterol
Category |
| Less than
200 mg/dL |
Desirable |
|
200–239 mg/dL |
Borderline high |
| 240 mg/dL
and above |
High |
|
LDL Cholesterol Level |
LDL Cholesterol
Category |
| Less than
100 mg/dL |
Optimal |
|
100–129 mg/dL |
Near optimal/above
optimal |
|
130–159 mg/dL |
Borderline high |
|
160–189 mg/dL |
High |
| 190 mg/dL
and above |
Very high |
|
HDL Cholesterol Level |
HDL Cholesterol
Category |
| Less than
40 mg/dL |
A major risk factor
for heart disease |
|
40–59 mg/dL |
The higher, the
better |
| 60 mg/dL
and above |
Considered protective
against heart disease |
|
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