Start With the Basics: CBC and CMP
Before considering specialized biomarkers or expensive longevity panels, it makes sense to start with the laboratory tests commonly used to evaluate overall health. Two of the most familiar are the Complete Blood Count and Comprehensive Metabolic Panel.
Complete Blood Count
The Complete Blood Count, commonly called a CBC, measures the cells circulating in your blood. This includes red blood cells, white blood cells, platelets, hemoglobin, hematocrit, and other measurements that provide information about the size and characteristics of your blood cells.
A CBC can help identify possible anemia, infection, immune system problems, certain nutritional deficiencies, and disorders affecting the blood or bone marrow. It may also be used to monitor medical conditions or medications that can affect blood cell counts.
An abnormal result does not automatically mean that something is seriously wrong. Hydration, medications, recent illness, and other factors can influence the numbers. Your healthcare provider will look at the pattern of results and determine whether additional testing is needed.
Comprehensive Metabolic Panel
A Comprehensive Metabolic Panel, or CMP, measures 14 substances in the blood. Together, they provide information about several important areas of health, including:
- Blood glucose
- Kidney function
- Liver function
- Electrolyte and fluid balance
- Calcium
- Protein levels
Some of the familiar markers included in a CMP are glucose, sodium, potassium, calcium, creatinine, blood urea nitrogen, albumin, bilirubin, ALT, AST, and alkaline phosphatase.
Because the CMP covers several body systems at once, it can help uncover changes that may not yet be causing noticeable symptoms. It can also help your healthcare provider monitor an existing condition or check whether a medication is affecting your kidneys, liver, or electrolyte balance.
You may sometimes see a Basic Metabolic Panel, or BMP, instead. A BMP measures eight of the same substances but does not include the liver enzymes, bilirubin, albumin, or total protein found in a CMP.
Kidney and Liver Function
The kidneys and liver perform many essential jobs, from filtering waste and regulating fluid balance to processing nutrients and medications. Several markers included in routine bloodwork can help your healthcare provider evaluate how these organs are functioning.
Kidney Function
Two numbers commonly used to assess kidney function are creatinine and estimated glomerular filtration rate, or eGFR.
Creatinine is a waste product produced during normal muscle metabolism. Healthy kidneys remove it from the blood. When kidney function declines, creatinine may rise because it is not being filtered as efficiently.
Creatinine has limitations, however. Muscle mass, diet, age, certain medications, and other factors can affect the result. A person with more muscle may naturally have a higher creatinine level, while an older adult with very little muscle may have a result that appears normal even when kidney function has declined.
eGFR uses creatinine along with factors such as age and sex to estimate how efficiently the kidneys are filtering blood. One unusual result does not necessarily indicate chronic kidney disease. Healthcare providers often learn more by following eGFR over time and considering it alongside other findings.
Another valuable test is the urine albumin-to-creatinine ratio, or uACR. This test checks for small amounts of albumin leaking into the urine. Albumin in the urine may be an early sign of kidney damage, even when creatinine and eGFR have not yet changed significantly. It is especially important for people with diabetes, high blood pressure, cardiovascular disease, or known kidney disease.
Pharmacist’s Tip: Tell your healthcare provider about all medications and supplements you take before interpreting kidney results. Certain products can affect creatinine or kidney function. If you use creatine, you may also find my guide, Does Creatine Hurt Your Kidneys?, helpful.
Liver Function
The liver processes nutrients, produces important proteins, helps regulate blood clotting, and breaks down many medications and other substances. Common liver-related markers include ALT, AST, alkaline phosphatase, bilirubin, and albumin.
ALT and AST are enzymes that may rise when liver cells are irritated or injured. ALT is more closely associated with the liver, while AST is also found in muscle and other tissues. This is why an elevated AST result must be interpreted alongside other laboratory findings.
Alkaline phosphatase can provide information about the liver and bile ducts, although it is also found in bone. Bilirubin is produced as red blood cells break down and is normally processed by the liver. Albumin is a protein made by the liver and may help provide information about its ability to perform certain functions.
Abnormal liver results can have many possible causes, including fatty liver disease, alcohol use, medications, supplements, viral infections, bile duct problems, and even strenuous exercise. These tests can identify a possible concern, but they usually cannot determine the cause on their own.