A full blood workup typically includes three core panels: a complete blood count (CBC), a comprehensive metabolic panel (CMP), and a lipid panel. Together, these cover roughly 30 individual measurements that assess your blood cells, organ function, blood sugar, and cholesterol. Depending on your age, health history, or risk factors, your doctor may add tests for thyroid function, vitamin D, or blood sugar control.
Complete Blood Count (CBC)
The CBC is one of the most commonly ordered blood tests and gives a broad picture of your overall health. It measures three main types of blood cells: red blood cells, white blood cells, and platelets.
For red blood cells, the CBC reports your hemoglobin level (the oxygen-carrying protein inside those cells), your hematocrit (what percentage of your blood is made up of red blood cells), and mean corpuscular volume, which is the average size of each red blood cell. These values together can flag anemia, dehydration, or nutritional deficiencies like low iron or low B12. Normal hemoglobin ranges differ by sex. In adults, men typically have a median around 13.9 g/dL while women average closer to 12.4 g/dL.
White blood cells fight infection, and the CBC reports a total white cell count. A version called a “CBC with differential” goes further, breaking that total into the five major types of white blood cells. This breakdown helps distinguish between bacterial infections, viral infections, allergic reactions, and more serious blood disorders. Platelet count rounds out the CBC, measuring the cells responsible for clotting. Low platelets can mean excessive bruising or bleeding risk, while high platelets may signal inflammation or another underlying condition.
Comprehensive Metabolic Panel (CMP)
The CMP measures 14 substances in your blood and is the workhorse panel for checking how well your organs are functioning. It covers four main areas: blood sugar, electrolytes, kidney markers, and liver markers.
Glucose is your fasting blood sugar level. Elevated glucose can indicate prediabetes or diabetes. The electrolyte portion includes sodium, potassium, chloride, and bicarbonate, which together reflect your body’s fluid balance, nerve signaling, and acid-base chemistry. Calcium is also included, playing a role in bone health, muscle function, and heart rhythm.
Two waste products, BUN (blood urea nitrogen) and creatinine, reveal how well your kidneys are filtering. Your doctor may use your creatinine level to calculate an estimated glomerular filtration rate, or eGFR, which is the standard way to gauge overall kidney function. Higher creatinine and BUN levels suggest the kidneys aren’t clearing waste efficiently. Creatinine levels also differ by sex, with men typically running higher than women.
The liver portion of the CMP includes three enzymes: ALP, ALT, and AST. When liver cells are inflamed or damaged, these enzymes leak into the bloodstream at higher levels. The panel also measures bilirubin, a waste product from the breakdown of old red blood cells that your liver processes and removes. Albumin and total protein round out the CMP, reflecting your liver’s ability to produce essential proteins. Low albumin can point to liver disease, kidney disease, or poor nutrition.
You may also hear about the basic metabolic panel (BMP), which is a slimmed-down version. It includes the same glucose, electrolyte, and kidney markers but skips the liver enzymes, bilirubin, albumin, and total protein. A “full” workup almost always means the CMP rather than the BMP.
Lipid Panel
The lipid panel measures fats circulating in your blood and is the primary screening tool for heart disease risk. It includes four values: LDL cholesterol (often called “bad” cholesterol because it builds up in artery walls), HDL cholesterol (“good” cholesterol that helps clear LDL from arteries), triglycerides (a type of fat your body uses for energy), and total cholesterol.
Your doctor interprets these numbers as a group rather than in isolation. High LDL combined with low HDL and elevated triglycerides paints a very different risk picture than a mildly high total cholesterol driven by strong HDL levels.
Common Add-On Tests
The three core panels cover a lot of ground, but a truly “full” workup often includes additional tests tailored to your situation. These are the most frequently added:
- Thyroid stimulating hormone (TSH): Screens for an underactive or overactive thyroid. This is routinely ordered for women, adults over 60, and anyone with fatigue, unexplained weight changes, or mood shifts.
- Hemoglobin A1c (HbA1c): Reflects your average blood sugar over the past two to three months. It’s more informative than a single fasting glucose reading for diagnosing and monitoring diabetes or prediabetes.
- Vitamin D (25-hydroxyvitamin D): Measures your stored vitamin D levels. Deficiency is common and can contribute to bone loss, fatigue, and immune issues. Normal ranges for adults are roughly 18 to 64 pg/mL.
- Iron studies: A ferritin level or iron panel may be added if your CBC suggests anemia, particularly if your red blood cells appear smaller than normal.
Your doctor may also order a urinalysis alongside bloodwork. While not a blood test, it’s a standard companion that checks for protein or sugar in urine, which can catch kidney problems or diabetes that blood tests alone might miss early on.
Fasting and Preparation
Most full blood workups require you to fast for 8 to 12 hours beforehand, meaning no food or drinks other than plain water. Fasting is especially important for accurate glucose and lipid panel results, since eating can temporarily spike blood sugar and triglycerides. The metabolic panel and liver function tests may also require fasting.
A CBC does not require fasting. If your workup includes only a CBC and your doctor hasn’t specifically told you to fast, you can eat normally. When in doubt, schedule your blood draw for the morning and skip breakfast. That covers fasting requirements for every panel at once.
What Happens During the Draw
A full blood workup is drawn from a single needle stick, usually from a vein in the inside of your elbow. The technician fills several small tubes, each color-coded for different tests. The entire draw takes about five to ten minutes. You might notice mild soreness or a small bruise at the site afterward.
Results for routine panels typically come back within one to three business days from an outpatient lab. Hospital labs processing urgent samples aim for under 60 minutes, but outpatient turnaround is slower because samples are often batched and transported to a central facility. Delays most commonly stem from transportation time and staffing at the lab, not from the testing itself.
How Reference Ranges Work
Every result on your report comes with a reference range, and numbers outside that range get flagged as high or low. These ranges are built from measurements of healthy people and represent the middle 95% of that population. That means 5% of perfectly healthy people will naturally fall just outside the range on any given test.
Reference ranges also vary by age and sex. Hemoglobin and creatinine run higher in men. Platelet counts tend to be higher in women. Children have significantly different normal values for white blood cells and platelets compared to adults. Young children, for example, typically have white blood cell counts around 8,500 per microliter, compared to about 5,900 in adults. A result that looks abnormal on paper may be completely normal for your demographic group, which is why your doctor interprets results in context rather than reacting to a single flagged number.