Understanding Lab Values

The Importance of Understanding Lab Values

     Why is understanding lab values an important skill for a caregiver? After all, the doctor reads the lab work and tracks what is going on with your family member.  Why not trust them to handle that part of the care alone?

Advantages of Knowing Lab Values

     Understanding lab work is not your responsibility as a caregiver; however, knowing lab values has its advantages. 

  1. Knowing lab values can help you predict what may happen next so that you can take appropriate action.
  2. Doctor’s don’t always catch changes in values that are unique to individuals. Family members do. You can bring significant changes in lab values to the doctor’s attention if they don’t notice. I have prevented serious medical problems that doctors overlooked twice by making those calls.
  3. Mentally, when you know normal lab values, it’s reassuring that your family member is doing well, especially if they don’t feel great. Also, if the labs are moving in a positive direction, it’s uplifting to see improvement.

Supplies for doing blood draws

Monitoring Lab Values at Home

     I keep urine test kits at home for monitoring kidney, liver, and overall metabolic functions. If Lynn starts to act “off” or feel ill, I’ll check to see if any of the values are out of the normal range. If they are, I take a second confirmation test, and if that is also positive and there is no other explanation, I call the doctor to get a recommendation for what I should do. By catching changes early, treatment can start before anything significant develops.

Understanding Lab Values Unlocks the Mysteries of the Body 

     Lab work unlocks the mysteries inside the body. We can’t see what’s happening there. However, as a nurse, I’ve learned that what I can’t see from the outside, I can find out from the blood. As blood circulates throughout the body, it picks up enzymes, proteins, and other waste products discarded from the organs. By measuring those cast-offs, we can determine how well the organs are functioning. When you compare values for two organs together, you can see the impact one organ has on the other when it is not working well. By running the right combination of blood tests and checking a urine specimen here and there, you can get a pretty comprehensive picture of what’s going on inside the body without cutting it open. When you understand lab values as a caregiver, you, too, have that insight.

CBC – Complete Blood Count

     A Complete Blood Count (CBC) is one of the most common tests ordered. The purpose of the test is to check your red blood cells, white blood cells, platelets, hemoglobin, and hematocrit levels along with some other supporting data, but those are the primary readings.


 Red Blood Cells – (RBC) Normal range 4.2 -6.1 x1012/L (also called erythrocytes) Are produced by the bone marrow and live about 120 days (4 months). Each RBC makes hundreds of thousands of hemoglobin molecules.  Body tissues, liver, and spleen destroy RBC.

Hematocrit – (Hct) The hematocrit is a percentage of RBCs in the total blood volume (i.e., red blood cells floating around in the blood plasma).  RBCs are separated from the rest of the blood plasma and counted as a percentage of everything left over to determine how they compare. It tells the M.D. how apt the patient is to keep up with the oxygen demand of his body. If his cells are few (low Hct) compared to the amount of fluid present, the test indicates anemia or fluid buildup such as congestive heart failure.  High Hct means the blood is “thicker” and has less liquid to dilute the RBC, indicating possible dehydration. 

White Blood Cells – (WBC) (also called leukocytes) Preferred range is 5.0 -10.0 x103. White blood cells are produced by bone marrow like RBC. Their job is to protect the body against infection. WBCs attack harmful organisms coming against us tries to destroy them, cleans up the carnage after the battle, create antibodies to protect us from that enemy for the future, and stimulates the bone marrow to get us ready for the next fight! Increased levels of WBC indicate inflammation, infection, autoimmune disorders, or leukemia. A drop in levels indicates possible prolonged suppression of the bone marrow.

Platelets – Although bone marrow also produces platelets, they are different from red and white blood cells. Instead of keeping things moving along, the smallest of the three blood cell siblings has the job of clogging up the works.  Unlike the white and red blood cells that keep blood flowing along, their little brother, platelet’s job, is to stick himself to any injured areas, form a clot, and clump a group of clots together initiating the healing process. Platelets are produced by the bone marrow but stored in the spleen till needed. There are usually 20% of our platelets in storage at any given time.

Complete Blood Count Values




Critical Values


14-17.3 g/dL

11.7-15.5 g/dL

<6.6 g/dL or > 20g/dL




<19.6% or >60%




<2×103/microL or >30×103/microL




relative to HGB – <1/3 of hgb




<30×103/microL, > 1000×103/microL

Checking blood sugar at home is one way to monitor how well a diabetic's insulin dose is handling their dietary intake, exercise level, illness stability, and daily activities.
Checking blood sugar at home is one way to monitor how well a diabetic's insulin dose is handling their dietary intake, exercise level, illness stability, and daily activities.

Metabolic Panel

     The metabolic panel is one of the most common blood tests ordered and may include 8 or 14 tests depending on how comprehensive the doctor wants to dig.  A basic panel has eight tests and looks primarily at electrolytes and kidney function in addition to glucose and calcium.  A comprehensive metabolic panel includes an additional six tests that focus on liver function and protein levels. The accumulation of all this information provides your healthcare provider with a wealth of information about your family member’s metabolism.


Why is Metabolism Important?

     Metabolism is how we convert food into energy and use that energy to make the body function properly. That process is essentially a chemical one and occurs through a series of organs doing their part first to mechanically break down the food and then to chemically decompose it to use for energy. If our organs don’t work correctly so that the chemicals get filtered in the right amounts, our body suffers the consequences. The Metabolic Panel tells us what organs are not doing their part if that happens.

The metabolic panel is divided into five primary categories. Miscellaneous (Glucose, Calcium), Electrolytes (Sodium, Potassium, Bicarbonate, Chloride), Kidney Function, (Blood Urea Nitrogen, Creatinine), Proteins, (Albumin, Total Protein), and Liver Tests (Alkaline Phosphatase, Alanine aminotransferase, Aspartate aminotransferase, Bilirubin).


Use Home Test Kits to Monitor Labs Values

   Once you have an understanding of lab values, you’ll want to keep an eye on them yourself all the time. One way to monitor lab values yourself is to buy home monitoring test kits. You can’t buy kits that allow you to draw venous blood samples because you can’t draw blood out of your own arm with a needle.  However, you can do finger sticks and urine tests. 

Many Types of Kits Available


     In today’s marketplace, many types of test kits are available for a variety of testing options. When I am suspicious that my husband might have a urinary tract infection, I use a test kit to check. By dipping a strip treated with special chemicals in urine, I can tell by the results if he has a possible infection. The results allow me to increase his fluid intake and take other action to flush out his urinary system. Most of the time, I can clear up the problem without antibiotics. That’s a win/win for us.

MUST Follow Directions Closely

     Most home test kits are easy to use; however, to be effective, you must follow directions precisely. Don’t be tempted, for example, to use the strips after the expiration date.  The chemicals won’t give accurate results. Throw them away! Always write the date you open the box on the package immediately. Throw away the contents remaining based on the manufacturer’s recommendations.

Home Health Monitoring Helps You Act Quickly    

      Home testing is a guideline that helps you to monitor your level of wellness and allows you to take corrective action quickly if needed.  However, its effectiveness is only as good as your willingness to follow the instructions on the kit correctly. Taking short cuts only hurts you or your family member.

  • Keep the test strips and chemicals dry and in a dark place.
  • Write the date opened on the container and throw away by the expiration day.
  • Time the test accurately
  • If you get an abnormal reading, do a second test, check to make sure that there is no other explanation for the abnormal result, and if not, notify the doctor of your findings.

Metabolic Panel Values

MetabolicMaleFemaleCritical Values
Glucose<100 mg/dL<100 mg/dL<40 mg/dL or > 400 mg/dL
Calcium8.4-10.2 mg/dL8.4-10.2 mg/dL<7 mg/dL or >12 mg/dL
Sodium135-145 mEq/L 135-145 mEq/L <120 mEq/L  o r  >160 mEq/L 
Potassium3.5-5.3 mEq/L3.5-5.3 mEq/L<2.5 mEq/L or >6.2 mEq/L
Bicarbonate (carbon dioxide)22-26 mEq/L22-26 mEq/L<15 mEq/L or > 40mEq/L 
Chloride97-107 mEq/L97-107 mEq/L<80 mEq/L or > 115 mEq/L
Blood Urea Nitrogen8-21 mg/dL 8-21 mg/dL>100 mg/dL
Creatinine0.61-1.21 mg/dL0.51-1.11  mg/dL>7.4 mg/dL (non-dialysis patient)
Albumin3.7-5.1 g/dL3.7-5.1 g/dL 
Total Protein6-8 g/dL6-8 g/dL 
Alkaline Phosphatase35-142 units/L25-125 units/L 
Alanine Amino Transferase (ALT,SGPT)6-38 units/L5-24 units/L 
Aspartate amino transferase (AST,SCOT)20-40 units/L15-30 units/L 
Bilirubin<1.1 mg/dL<1.1 mg/dL>15 mg/dL


The Components of the Metabolic Panel

Glucose – Glucose is the primary energy source for the body’s cells. A steady supply must be available for use, and a relatively stable level of glucose maintained in the blood.  Insulin transfers extra glucose from the blood to muscle, fat, and liver cells for storage, and the body burns it as needed for energy.

Calcium – Calcium is one of the most important minerals in the body. It is essential for the proper functioning of muscles, nerves, and the heart and required in blood clotting and the formation of bones. Calcium levels are regulated by the parathyroid gland and by Vitamin D.

Sodium – Sodium is vital to normal body function, including nerve and muscle function. It is the most abundant electrolyte outside the cells and is essential to maintaining the osmotic pressure of the extracellular fluid for acid/base balance.

Potassium – Potassium is necessary for cell metabolism and muscle function, helping to transmit messages between nerves and muscles.  Abnormal potassium levels can significantly affect the electrical impulses in the heart muscle and lead to painful cramping in skeletal muscles. It plays a significant part in transforming glucose into energy and amino acids into proteins.

Bicarbonate (Total CO2) – Bicarbonate helps to maintain the body’s acid-base balance (pH). It provides the primary buffering system for the extracellular fluid system that flows throughout the body with CO2 bound to protein or physically dissolved.

Chloride – Chloride participates with sodium in maintaining the water balance and regulating osmotic pressure. Chloride contributes to gastric acid (hydrochloric acid) for digestion and activates enzymes to help break down our food.  We get most of our chloride from food in the form of salt (sodium chloride). The kidneys get rid of any unneeded chloride using our elimination processes-i.e., urine output.

Blood urea nitrogen (BUN) – The body cannot store protein.  Amino acids and nitrogen make proteins from the food we eat. Urea is a nonprotein nitrogen (NPN) compound formed in the liver from ammonia and excreted by the kidney as a product of protein metabolism. Other NPN compounds excreted by the kidneys include uric acid and creatinine. Evaluating uric acid and creatinine levels together is a good way to measure kidney functioning. As the BUN level rises, its a clear indication that the kidney function is declining.

Creatinine – As mentioned above, Creatinine is another waste product of protein breakdown and often is a byproduct of muscle use.  Creatinine is filtered out of the blood by the kidneys, so blood levels are a good indication of how well the kidneys are working.

Albumin – Albumin is a small protein made by the liver; it makes up about 60% of the total protein in the blood.

Total Protein – Total Protein measures albumin as well as all other proteins in blood; proteins are important building blocks of all cells and tissues and are essential for body growth, development, and health.

Alkaline phosphatase (ALP) – An enzyme found in bone, the liver, and other tissues. Liver disease or bone disorders commonly cause elevated levels of ALP in the blood. 

Alanine aminotransferase (ALT, SGPT) – An enzyme found mostly in the cells of the liver and kidney; a useful test for detecting liver damage

Aspartate aminotransferase (AST, SGOT) – AST is an enzyme found primarily in cells in the heart and liver but serves as a useful test for detecting liver damage, too.

Bilirubin – An orange-yellow pigment, a waste product primarily produced by the normal breakdown of heme; heme is a component of hemoglobin, found in red blood cells (RBCs). The liver removes bilirubin from the body after processing.