Blood tests are a typical and crucial diagnostic method used in medicine. They offer crucial details on a person’s health status, including the identification of medical conditions and the tracking of treatment outcomes. Both medical professionals and people must be aware of the many blood test kinds, normal ranges, and abnormal indicators. The significance of blood tests and what they can tell us about a person’s health are discussed in this article.
Complete Blood Count (CBC)
A complete blood count (CBC) is a blood test that determines the number of red blood cells, white blood cells, and platelets in your blood.
The normal values for a CBC are:
- Red blood cells (RBC): 4.5 to 5.5 million cells/mcL (males) and 4.0 to 5.0 million cells/mcL (females)
- White blood cells (WBC): 4,500 to 11,000 cells/mcL
- Platelets: 150,000 to 450,000/mcL
- Hemoglobin (Hb): 13.5-17.5 grams/dL for men and 12.0-15.5 grams/dL for women
- Hematocrit (Hct): 38.8%-50.0% for men and 34.9%-44.5% for women
Abnormal CBC results can indicate various conditions, such as anemia (low RBC), infection (high WBC), or thrombocytopenia (low platelets).
Liver Function Test (LFT)
A liver function test (LFT) examines enzymes and proteins in your blood to determine how effectively your liver is working.
The normal values for LFTs are:
- Alanine Aminotransferase (ALT): 10 to 40 U/L in men; 7 to 35 U/L in women
- Aspartate Aminotransferase (AST): 10 to 34 U/L in men; 9 to 30 U/L in women
- Alkaline phosphatase (ALP): 45 to 115 units/L
- Bilirubin: 0.1 to 1.2 mg/dL
Abnormal LFT results can indicate liver damage or disease, such as hepatitis, cirrhosis, or liver cancer.
Kidney Function Test (KFT)
A kidney function test (KFT) detects chemicals in your blood and urine that reflect how effectively your kidneys are working.
The normal values for KFTs are:
- Blood urea nitrogen (BUN): 6 to 20 mg/dL
- Creatinine: 0.6 to 1.2 milligrams per deciliter (males) and 0.5 to 1.1 milligrams per deciliter (females)
- Glomerular Filtration Rate (GFR): >90 mL/min
- Urine protein: 0 to 20 mg/dL
Abnormal KFT values can suggest kidney injury or disease, such as chronic kidney disease, glomerulonephritis, or kidney stones.
A lipid profile assesses the many forms of lipids in your blood, including cholesterol and triglycerides. This test checks levels of two of cholesterol:
- high-density lipoprotein (HDL), or “good” cholesterol
- low-density lipoprotein (LDL), or “bad” cholesterol
The normal values for a lipid profile are:
- Total cholesterol: less than 200 mg/dL
- High-Density Lipoprotein (HDL) cholesterol: 40 to 60 mg/dL
- Low -Density Lipoprotein (HDL) cholesterol: less than 100 mg/dL
- Triglycerides: less than 150 mg/dL
An abnormal lipid profile can suggest an increased risk of cardiovascular disease, such as atherosclerosis, heart attack, or stroke.
Blood Sugar Test
A blood sugar test determines the concentration of glucose (sugar) in your blood.
The normal values for a blood sugar test are:
- Fasting blood sugar (FBS): 70 to 100 mg/dL
- Postprandial blood sugar (PPBS): less than 140 mg/dL
- Hemoglobin A1C (HbA1C): less than 5.7%
Abnormal blood sugar test results can suggest diabetes, insulin resistance, or other metabolic diseases.
Thyroid Function Test (TFT)
A thyroid function test (TFT) measures the levels of various hormones produced by your thyroid gland.
- Triiodothyronine (T3). Along with T4, this regulates your heart rate and body temperature.
- Thyroxine (T4). Along with T3, this regulates your metabolism and how you grow.
- Thyroid-stimulating hormone (TSH). This helps regulate the levels of hormones your thyroid releases.
The normal values for TFTs are:
- Thyroid-stimulating hormone (TSH): 0.4 to 4.0 mIU/L
- Free T4: 0.8-1.8 ng/dL
- T3: 80–180 nanograms per deciliter of blood (ng/dL)
Abnormal TFT values could indicate an underactive or overactive thyroid gland, which can cause symptoms such as fatigue, weight gain or loss, and mood changes.
C-reactive protein test
The liver produces C-reactive protein (CRP) when bodily tissues are irritated.
Increased CRP levels are a sign of inflammation due to a number of conditions, including cancer, bacterial or viral infections, autoimmune disorders like Lupus or rheumatoid arthritis, diabetes-related inflammation, inflammation brought on by physical trauma or bad habits like smoking.
The higher the level, the higher the risk of heart disease.
- <0.3 mg/dL: normal
- 0.3 to 1.0 mg/dL: minor elevation can be associated with a person’s sex, body mass index (BMI), or with conditions like depression or insomnia
- 1.0 to 10.0 mg/dL: moderate elevation usually caused by systemic inflammation, such as from an autoimmune disease, bronchitis, heart attack, or cancer
- >10.0 mg/dL: marked elevation typically caused by a serious bacterial or viral infection, major trauma, or systemic vasculitis
- >50.0 mg/dL: severe elevation usually caused by an acute bacterial infection
Sexually transmitted infection tests
A blood sample can be used to identify many sexually transmitted diseases (STIs). For more precise diagnoses, these tests are additionally paired with urine samples or swabs of affected tissue.
The following STIs can be diagnosed with blood tests:
Blood tests aren’t always accurate right after contracting an infection. For an HIV infection, for example, you may need to wait at least a month before a blood test can detect the virus.
Testing for coagulation measures the speed and effectiveness of blood clotting. Examples include the fibrinogen activity test and the prothrombin time (PT) test.
Clotting is an essential step in the process of stopping bleeding from a cut or wound. A clot in an artery or vein, however, can be fatal because it can obstruct blood flow to the heart, lungs, or brain. Heart attack or stroke risk due to this.
The health and any underlying problems that can affect clotting can alter the results of a coagulation test.
Results from this test can be used to diagnose:
- excessive bleeding (hemophilia)
- liver conditions
- vitamin K deficiency
DHEA-sulfate serum test
The dehydroepiandrosterone (DHEA) hormone comes from your adrenal glands. This test measures whether it’s too high or too low.
In men, DHEA helps develop traits like body hair growth, so low levels are considered abnormal. In women, high levels can cause typically male traits, like excess body hair, to develop, so low levels are normal.
Low levels may be caused by:
- Addison’s disease
- adrenal dysfunction
High levels in men or women can result from:
- congenital adrenal hyperplasia
- benign or malignant tumor on the adrenal gland
- polycystic ovary syndrome (PCOS)
- ovarian tumor
Blood Pressure Test
Blood pressure is a measurement of the force that blood exerts against the walls of your arteries. High blood pressure or hypertension can lead to serious health complications, such as heart attack, stroke, and kidney failure.
The normal blood pressure range is 120/80 mmHg. Any reading above this range is considered high.
How long does it take to get the result?
- complete blood count (CBC): 24 hours
- basic metabolic panel: 24 hours
- complete metabolic panel: 24 to 72 hours
- lipid panel: 24 hours
Doing a blood test may not be on most people’s list of entertaining activities, but medical professionals use them as a crucial tool to check general health or identify medical disorders. A blood test may be required during a normal physical checkup or when specific symptoms are present. It’s important to understand that blood tests aid in diagnosing medical conditions but do not constitute diagnoses. An abnormal blood test result does not necessarily indicate a major medical problem. If your healthcare professional suggests a blood test, they will explain why and what the test may reveal.