Blood chemistry tests are often done before surgery to assess a person's general health. The testing panel, commonly known as Chem 7 because it tests for seven different substances in the blood, is also usually done after surgery to make sure the person is okay in the days after surgery.
This test is known by various names, including Computer Aided Multichannel Sequential Analysis 7 (SMAC7) or Metabolic 7, but most healthcare professionals refer to it as Chem 7 or Basic Metabolic Panel (BMP). The Comprehensive Metabolic Panel (CMP) is similar but includes six additional tests.
The seven tests that make up the Chem 7 panels (in alphabetical order) :
- Blood urea nitrogen (AMK)
- Carbon dioxide
- Serum chloride
- Serum potassium
- Serum sodium
What to expect
Your healthcare provider may order the Chem 7 test a few days before your procedure or just before your surgery. For the test , blood will be drawn from a vein or intravenous (IV) line. Usually the lab can return results very quickly.
Once the results are obtained, the laboratory report will indicate the control ranges for each of the seven test substances. The result is considered normal if it is between the high and low values of the range.
Anything below or above the control range is considered abnormal, although there is some flexibility in interpreting the results based on your age, your general health (including chronic conditions), and even your location.
If the values are 'abnormal' (that is, excessively high or excessively low), you may not be able to have surgery or need medical attention before you can.
Test results can be described in different ways depending on where you live.
In the United States, blood test results are generally described in standard metric terms, such as milliliters (ml) or milligrams per deciliter (mg / dL). Internationally, they are often described in metric terms of concentration, such as millimoles per liter (mmol / L) or micromoles per liter (μmol / L).
Blood urea nitrogen (AMK)
Blood urea nitrogen (BUN) is an indicator of kidney function. It measures the amount of nitrogen in your blood that comes from urea waste. Urea is formed when the kidneys break down proteins. A high level may indicate that the kidneys are not working well than usual .
Normal adult AMK values are in the range:
- 8 to 23 mg / dL (US )
- 2.9 to 8.9 mmol / L (international )
Carbon dioxide (CO2)
This test measures the amount of carbon dioxide in your blood . Most of the carbon dioxide is in the form of bicarbonate, which is regulated by the lungs and kidneys. The test result shows how well the kidneys, and sometimes the lungs, deal with bicarbonate in the blood .
Normal CO2 values for adults are in the range:
- 22 to 28 mEq / L (US )
- 22 to 29 mmol / L (international )
Normal creatinine values for adults are in the range:
- 0.6 to 1.2 mg / dL (US )
- 7.0 to 17.6 μmol / L (international )
Be aware that certain medications and the timing of the test, depending on food intake, can dramatically change the results. This is why glucose tests are usually done on an empty stomach, especially before surgery.
Normal glucose values for adults are in the range:
- 70 to 110 mg / ml (US )
- 3.9 to 6.1 mmol / L (international )
Chloride levels can vary greatly if a person is dehydrated or overweight. This could be a sign that your kidneys are not working properly. Heart failure and endocrine problems can also contribute to abnormal Cl results .
Normal serum chloride levels in adults are in the range:
- 96 to 106 meq / L (US )
- 96 to 106 mmol / L (international )
The serum potassium (K) test measures the level of potassium in the blood. Potassium plays an important role in muscle contraction and cell function. Both high and low potassium levels can cause heart rhythm problems, so it is important to monitor potassium levels before and after surgery .
People who take diuretics regularly may need regular blood tests to monitor potassium levels because some diuretics can cause the kidneys to excrete too much potassium .
Normal values for serum potassium in adults are in the range:
- 3.5 to 5.0 meq / L (US )
- 3.5 to 5.1 mmol / L (international )
The serum sodium (Na) test measures the amount of sodium in your blood. The kidneys remove excess sodium from the body, which is ingested through food and drink. Sodium levels can fluctuate depending on dehydration or overhydration, diarrhea, endocrine disorders, trauma, bleeding, and other causes .
Normal serum sodium values for adults are in the range:
- 136 to 142 meq / L (US )
- 135 to 145 mmol / L (international )
Get the word of drug information
Chem 7 is an invaluable blood test that presents little risk. You may have mild pain or bruising where the blood was drawn, but most symptoms clear up quickly. If the exam is scheduled a few days before surgery, you may need to fast. If you are not sure, check with your doctor twice.