Normal Lab Values
What Do My Labs Mean?
When you look at your labs through your Patient Portal, or get a copy of your labs from your doctor, they typically come with "Reference Ranges." It's important to be aware that these are not necessarily the "normal" or "healthy" numbers. They are the average taken from a certain population, and your doctor makes decisions about what's a "good result" for you based on your medical history, several sets of guidelines, and the medications that you're taking.
Ultimately, if you have questions about your labs you should ask your doctor. However, the following explanation can hopefully give you a better basic understanding of what these basic labs are, what they mean, and what they're used for. You doctor may also look at different levels and labs to further determine what's going on.
Blood Counts
One of the most common blood tests is a "CBC", or Complete Blood Count.
WBC, White Blood Cells - Normal: 4.5-11 (thousand). This is a marker of infection, with anything from a virus, bacteria, or fungus. This is further broken down into different types of white blood cells which tells your doctor what type of infection you may have. If these numbers are lower than 4.5 or higher than 11, both of these can indicate an infection.
Hgb, Hemoglobin - Normal: 13-17.5 (grams per deciliter) for men, and between 12-16 (grams per deciliter) for women. This is one of the proteins found in red blood cells, and it is used as an indicator for how much blood you have. Low numbers indicate anemia, or lack of red blood cells to carry oxygen and nutrients throughout your body. High numbers mean your body is working harder than normal to transport things through your body, and can indicate things like lung disease, sleep apnea, or even dehydration.
Hct, Hematocrit - Normal: 39-52% for men, and 36-42% for women. This is a measure of concentration of red blood cells in your veins, and is typically about three times the Hemoglobin so only one or the other is often reported.
Plt, Platelets - Normal: 150-450 (thousand). These are the parts of your blood which help you to clot when you get a small scratch or nick. If these get too low, doctors worry about you not clotting well when you start to bleed. If these are too high, than can be an indicator of anything from dehydration to certain cancers.
MCV, Mean Corpuscular Volume - This is the average size of your red blood cells. This is the most important factor to determine why you may have anemia: small blood cells (low MCV) can be caused by iron deficiency, lead, or certain blood disorders. Large blood cells (high MCV) can be caused by B12 deficiency or Folate deficiency, as well as certain medications. Normal may indicate bleeding, or a mix of things that cause both low & high MCV cancelling out.
MCH, Mean Corpuscular Hemoglobin - This is the average amount of hemoglobin in each red blood cell. Low can be an indication of iron deficiency or certain blood disorders, high can be an indication of Vitamin B12 or Folate deficiencies.
MCHC, Mean Corpuscular Hemoglobin Concentration - This is a measure of how densely packed the red blood cells are, and isn't often used for many determinations.
RDW, Red cell Distribution Width - This is a measure in the variation of sizes of red blood cells. A high RDW means that there is a big range of blood cells, small to large. This usually indicates that your blood count WAS low and that your body is replacing blood cells as quickly as it can.
Electrolytes, Kidney, and Liver Function
Another very common blood tests is a "BMP", or Basic Metabolic Panel. This examines your electrolytes and kidney function. It is different from a "CMP" or Complete Metabolic Panel in that a CMP also examines your liver enzymes and function.
Glu, Glucose - Normal: from 75-124, but may depend on how long you had been fasting for. This is the measure of the sugar in your body at the time your blood was drawn. If you have anything with sugar or carbohydrates prior to getting her blood drawn, this will artificially inflate these numbers.
eGFR, Estimated Glomerular Filtration Rate - Normal: varies depending on age, but should be greater than 60. This is an estimate based on multiple lab values that is calculated by the lab and your doctor. This is an estimate that provides a "rough percentage" of your kidney function. Chronic kidney disease is staged based on this number, and as it drops below 40 you should see a nephrologist, or kidney doctor. You may need dialysis if this number drops below 5.
Na, Sodium - Normal: 135-145. While we directly measure sodium, this is a measure of your fluid levels. If you have too much water within you, the sodium is diluted and drops. If you aren't dehydrated, this number can rise. People with normal kidneys can adjust this automatically, but certain medications can cause problems with this value.
Cl, Chloride - Normal: 98-107. This is the other half of "table salts" that goes along with sodium. We use this to measure hydration as well as certain medications.
K, Potassium - Normal: 3.5-5.1. This is one of the electrolytes that we get from a regular diet. If you have problems with her kidneys, sometimes doctors keeping medicines to decrease this to avoid dangerously high levels. If you're taking diuretics, or "water pills", you may need to take a supplement to replace what is lost.
CO2, Carbon Dioxide - Normal: 20-30. This is not the traditional Carbon dioxide that we talk about with gases, but instead is a measure of the level of acid and base in your body. This is something that doctors use to identify what is wrong when you are very sick.
BUN, Blood Urea Nitrate - Normal: from 7-18 (milligrams per deciliter, or mg/dL). A marker of your kidney function, this number increases as your kidney function decreases. It can be elevated through dehydration, or a few medications.
Cr, Creatinine - Normal: Less than 1.1mg/dL This is a normal marker of protein that is found in your muscle. Small people with low body weight will naturally have a lower creatinine within larger people who are heavily muscled. As this waste product is eliminated by the kidneys, when the kidneys are doing poorly the amount in your blood increases
ALT, Alanine AminoTransferase - Normal: 12-78, and AST, Aspartate AminoTransferase - Normal: 15-37. Both of these are enzymes found within the liver cells. When you have liver injury from toxins, fatty liver disease, or alcoholic liver disease, these can be elevated.
Alk Phos, Alkaline Phosphatase - Normal: 30-120. This is an enzyme that is created by her liver, and when there is inflammation or blockages from structural problems, liver disease, and other issues this number can be elevated. This enzyme is also created by the bones, and so occasionally certain bone diseases can cause an elevation in discomfort. Dr. can use further blood tests to determine whether this comes from the liver or from her bones.
Bili, Bilirubin. This is broken up into direct (or conjugated) bilirubin and indirect (or unconjugated) bilirubin. This is one of the body's breakdown substances which is converted from an "unconjugated" form that can be toxic into a "conjugated" form which can be safely expelled from the body. This is the substance that causes your urine to be dark, and her bowel movements to be brown. If you have liver problems or blockages in your GI tract these numbers can be elevated. Your body can also create more bilirubin than it can "conjugate" (convert into a healthy form) if your blood cells are being broken up. This can happen from certain medications or illnesses.
AGAP, Anion Gap - Normal: <12. This is a calculation made by subtracting the chloride, the carbon dioxide, and sometimes the potassium (depending on your lab) from the sodium. This difference can be used to tell your doctor where a problem is coming from. The good news is that if there's no problem, you can ignore this value entirely! Some things it can help to differentiate between are lactic acidosis, kidney failure, toxic ingestion, diabetic coma, gastrointestinal issues, and many other things.
HbA1c, HgA1c, Hemoglobin A1c - Normal: <6.5%. This is an estimated measure of the 90-day average of your blood sugar. A blood glucose can check how much sugar you have at that exact moment, but this is affected by so many things it's hard to base many medical decisions based on it. Depending on your age, your other illnesses, and your general medical history, you should ask your doctor what your goal is if you are diagnosed with diabetes. For most people, this will be below 7.5%.
Thyroid Labs
TSH, Thyroid Stimulating Hormone - Normal: Somewhere between 0.5-5.0 (can vary between labs). This is the hormone that your pituitary gland makes in order to get the thyroid do its job. Paradoxically, when this number is high that means that your thyroid isn't working as much as it should (also known as "hypothyroidism" or "slow thyroid"). If your TSH is too low, then that means your thyroid is working too hard. Sometimes this fluctuates outside of the normal range, and if actual thyroid hormone (T4) is normal, then it can just be monitored and called "subclinical hypothyroidism." Thyroid medicine often doesn't change symptoms, so doesn't always need to be treated!
T4, Free T4, or Thyroxine - Normal: Somewhere between 0.8-1.8 (can vary between labs). This is the actual hormone that your thyroid makes. This accounts for 95% of circulating thyroid hormone, and it gets slowly converted to T3 (which is more difficult to accurately measure, and less useful).
T3, Free T3, or Triiodothyronine - Normal: .08-.220 (can vary between labs, time of day, and many other factors). This is a difficult factor to accurately measure and not nearly as relevant as T4. There are very few circumstances in which it is evidence-based to order T3 levels.
Cholesterol
Cholesterol, Total - Normal: 100-200. This has a large range of normal values, due to the fact that it is the sum total of all different types of your cholesterol. While it is important to keep an eye on this, the individual components affect the outcome more than anything else
TG, Triglycerides - this is one of the harmful components of cholesterol. These typically rise from eating, and is the only component of your cholesterol test that is affected by whether you are fasting or not when you have your blood drawn. Certain genetic inherited disorders can raise this, requiring medications to control it and reduce your risk of heart attacks and strokes.
<150 - Normal
150-199 - Borderline High
200-499 - High
>500 - Very High
HDL, High Density Lipoprotein - Normal: >40. The "good" cholesterol. This is the value that protects you from all of the others. Sometimes when your total cholesterol is high, if this value is what brings it up, you are actually doing okay. Good genetics, exercise, healthy diets with decreased red meat intake can all lead to good values. Some studies have shown that one moderate sized glass of alcohol a day, especially wine, can help.
LDL, Low Density Lipoprotein - Normal: <90. The "bad" cholesterol. Depending on what risk values you have, including diabetes, high blood pressure, or heart disease, he may have a different goal for this number. In general, he wants this to be low. Your doctor may put you on a medicine to help control this.
VLDL, Very Low Density Lipoprotein - Normal: 8-32. Also "bad" cholesterol. Not something that is looked at as often, the goal for this is to have this on the low end of normal.
Urine Protein Tests
Urine Albumin - Normal: N/A. This has a large range of normal values, and is affected by your hydration status, your diet, your muscle mass, and many other things. It's affected by so many elements, in fact, that it's not a very useful number in and of itself.
Urine Creatinine - Normal: N/A. This has a large range of normal values, and is affected by your hydration status, your diet, your muscle mass, and many other things. It's affected by so many elements, in fact, that it's not a very useful number in and of itself.
Urine (micro)Albumin to Creatinine Ratio - Normal: <30. As each individual component is so variable, it's only the ratio that is useful. Less than 30 means that your kidneys are letting go of waste products well, filtering out good proteins, and reabsorbing what they need to. 30-300 means "moderate" albuminuria or "microalbuminuria." This indicates your kidneys are starting to decline. >300 means that your kidneys are not working well at all.
General Urine Tests
Color - Normal: Clear to Light Yellow. This can be affected by foods (caffeine can make it bright yellow, beets can turn it red, certain medications can turn it dark orange, brown, or red). In general if you are drinking enough water it will be a light color, and if you are getting dehydrated it will turn darker.
Clarity/Turbidity - Normal: Clear. Sometimes lower urinary tract issues or kidney issues can lead to cloudy urine. This does not automatically mean it is an infection, but instead can represent a wide range of things (many of which are normal).
pH - Normal: 4.5-8. This is the level of acidity in your urine. Usually urine is slightly acidic but this can be influenced by medications, and diet (for example, a vegetarian diet can lead to more basic urine). This is not typically very useful by itself to indicate anything of note.
Specific Gravity - Normal: 1.005-1.025. This is a ratio of the density of urine to the density of water. 1.0 would indicate equal density, so the lower the number the more hydrated one is. If the number is too low it can indicate that your kidneys are having a hard time concentrating urine. If the number is too high it can indicate that protein is being spilled, or that you're not getting enough water in.
Glucose - Normal: None. Ordinarily sugar ("glucose") shouldn't build up sufficiently in your blood to be spilled into urine. If found in the urine this could indicate illness, certain medications (like steroids), and potentially diabetes.
Ketones - Normal: None. Ketones are a breakdown product of fat, when sugar can't be used. This can be seen if you haven't been eating for a while, if there's been vomiting, or in diabetes (as your body can't process the sugar efficiently).
Nitrites - Normal: None. Nitrites are products of breakdown of certain bacteria, such as E. coli (the most common cause of Urinary Tract Infections, or UTI's). If found in urine, they're very predictive of a UTI. If absent, it does not rule out a UTI however!
Leukocyte Esterase - Normal: None. Leukocyte Esterase (or "leuk esterase") is an enzyme made by neutrophils, a type of white blood cells. They can be seen in UTI's, but can also be found during yeast infections or other non-UTI issues. Thus, if absent, a UTI is much less likely. If present, it's predictive but not diagnostic of a UTI.
Bilirubin - Normal: None. This is the breakdown product of blood cells and waste in the body, that is processed by the liver. While this is abnormal, sometimes the test will only show bilirubin and not each individual product, so this must be taken into account.
Urobilirubin - Normal: 0-1. This is the normal part of bilirubin that is excreted in urine. Sometimes the test will only show bilirubin and not each individual product, so this must be taken into account.
Blood - Normal: <3 RBC's/hpf (Red Blood Cells per high-powered field). While this can be caused by urinary tract infections, kidney stones, or trauma, there are a few important considerations. In women who are menstruating, sometimes blood from the vagina can be caught by the urine and show up. In children, sometimes strenuous exercise can cause mild hematuria (blood in the urine). Lastly, in adults, painless blood in the urine is never normal and should be worked up for potential cancer.
Squamous Epithelial Cells - Normal: None. These are cells that are found on the outside of the body, and outside the urinary tract. If many are seen, it indicates that the sample may have been contaminated and that it may be worthwhile to get another if anything abnormal is found.
Casts - Normal: None. These are still-formed clumps of cells that are shaped like part of the kidney. They can be formed out of protein, blood, kidney cells, or white blood cells. They all mean different things, but typically are only seen in some type of disease.