Understanding Common Laboratory Tests
1. Complete Blood Count (CBC)
The complete blood count (CBC) is one of the most frequently ordered blood tests. It measures several components of your blood, including:
- Red blood cells (RBCs) – Carry oxygen throughout the body.
- White blood cells (WBCs) – Fight infections and support the immune system.
- Hemoglobin and hematocrit – Indicate the oxygen-carrying capacity of blood.
- Platelets – Help with blood clotting.
Why it’s important:
A CBC can help detect conditions like anemia, infections, inflammation, bleeding disorders, and leukemia. If you feel tired, weak, or have unexplained bruising or infections, your doctor may recommend this test.
2. Basic Metabolic Panel (BMP)
The basic metabolic panel checks for key substances in your blood to evaluate organ function. It typically measures:
- Glucose (blood sugar)
- Calcium
- Sodium
- Potassium
- Chloride
- Carbon dioxide (CO₂)
- Blood urea nitrogen (BUN)
- Creatinine
Why it’s important:
This test helps assess how well your kidneys are working, your electrolyte balance, and your blood sugar levels. It’s often used to monitor diabetes, kidney disease, or dehydration.
3. Comprehensive Metabolic Panel (CMP)
A comprehensive metabolic panel includes everything in the BMP, plus tests that evaluate liver function, such as:
- Albumin and total protein
- Alkaline phosphatase (ALP)
- Aspartate aminotransferase (AST)
- Alanine aminotransferase (ALT)
- Bilirubin
Why it’s important:
The CMP provides a more complete picture of your metabolism and organ health. Abnormal results may indicate liver disease, diabetes, kidney issues, or nutritional deficiencies.
4. Lipid Panel
The lipid panel measures the levels of different fats in your blood, including:
- Total cholesterol
- LDL (“bad”) cholesterol
- HDL (“good”) cholesterol
- Triglycerides
Why it’s important:
This test helps assess your risk of heart disease or stroke. High levels of LDL or triglycerides can increase your risk, while high HDL levels are protective. Doctors often recommend this test for adults over 20 and more frequently for those with risk factors like obesity, diabetes, or a family history of heart disease.
5. Thyroid Function Tests
The thyroid gland controls metabolism, energy levels, and body temperature. Thyroid function tests typically include:
- TSH (thyroid-stimulating hormone)
- T3 (triiodothyronine)
- T4 (thyroxine)
Why it’s important:
These tests help detect hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid). Symptoms such as fatigue, weight changes, or mood swings may prompt your doctor to order these tests.
6. Hemoglobin A1c (HbA1c)
The A1c test measures your average blood sugar levels over the past 2 to 3 months.
Why it’s important:
It’s used to diagnose and monitor diabetes. A result of 5.7% to 6.4% indicates prediabetes, and 6.5% or higher usually confirms diabetes. Regular A1c testing helps ensure that blood sugar levels are under control to prevent long-term complications.
7. Urinalysis
A urinalysis examines your urine for abnormalities such as:
- Protein
- Glucose
- Ketones
- Blood
- Bacteria or white blood cells
Why it’s important:
This test helps identify urinary tract infections (UTIs), kidney disease, diabetes, and liver problems. It’s a simple, non-invasive test often done during routine physical exams.
8. Liver Function Tests
Your liver plays a vital role in detoxification, digestion, and metabolism. Liver function tests (LFTs) measure enzymes and proteins such as:
- ALT (alanine aminotransferase)
- AST (aspartate aminotransferase)
- ALP (alkaline phosphatase)
- Bilirubin
- Albumin
Why it’s important:
Abnormal results may indicate liver inflammation, hepatitis, alcohol-related damage, or bile duct problems. These tests are also used to monitor patients taking medications that affect the liver.
9. Coagulation Tests
Coagulation tests evaluate how well your blood clots. Common tests include:
- Prothrombin Time (PT)
- Partial Thromboplastin Time (PTT)
- INR (International Normalized Ratio)
Why it’s important:
These tests are crucial for patients taking blood thinners (anticoagulants) or those with bleeding disorders. They help doctors determine the right medication dosage and ensure you’re not at risk of excessive bleeding or clotting.
10. Vitamin and Mineral Tests
These tests measure levels of nutrients such as:
- Vitamin D
- Vitamin B12
- Iron and ferritin
- Calcium and magnesium
Why it’s important:
Deficiencies in essential vitamins or minerals can lead to fatigue, bone weakness, anemia, and nerve issues. Regular testing helps identify dietary gaps and supports proper supplementation.
11. Infectious Disease Tests
Lab tests are key tools in detecting infections caused by bacteria, viruses, or parasites. Some common tests include:
- HIV test
- Hepatitis panel
- COVID-19, flu, or strep tests
- STD/STI screenings
Why it’s important:
Early detection allows for timely treatment and prevents the spread of infection. Many of these tests can be done using blood, saliva, or swabs.
12. Pregnancy Test
A pregnancy test detects the hormone hCG (human chorionic gonadotropin) in blood or urine.
Why it’s important:
This test confirms pregnancy, but it can also help detect ectopic pregnancies or monitor certain cancers that produce hCG.
13. C-Reactive Protein (CRP) and ESR
Both CRP (C-reactive protein) and ESR (erythrocyte sedimentation rate) are markers of inflammation in the body.
Why it’s important:
Elevated levels may indicate infections, autoimmune disorders (like rheumatoid arthritis or lupus), or chronic inflammation related to heart disease.
14. PSA Test (Prostate-Specific Antigen)
The PSA test measures the level of prostate-specific antigen in men’s blood.
Why it’s important:
High PSA levels may indicate prostate cancer, enlargement, or inflammation. Men over 50 (or those at higher risk) are often advised to get this test regularly.
15. Blood Type Test
A blood typing test identifies your blood group (A, B, AB, or O) and Rh factor (positive or negative).
Why it’s important:
Knowing your blood type is essential for safe blood transfusions, organ transplants, and pregnancy management if Rh incompatibility is a concern.