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Understanding Lab Values

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. 

Oxygen Transportation

When more oxygen is needed, the kidney secretes a red blood growth factor called erythropoiesis to stimulate the production of more Red Blood Cells in the bone marrow, so there is more hemoglobin produced to carry more oxygen! Other factors affecting Hemoglobin and Red Blood Cell production include levels of iron, vitamin B12, folic acid, copper, pyridoxine (B6), cobalt, and nickel.  A deficiency in any of these substances can cause anemia, which can lead to a reduction in the number of RBC produced—subsequently affecting the amount of hemoglobin and oxygen circulated.

RBC or Hgb Deficiency

If you know that you have a deficiency in some of these elements along with a low RBC or HGB count, a change in diet might be a way that you, as a caregiver, could make a change at home to improve the health of your family member. By serving foods high in these substances, you could improve their health overall and possibly eliminate their need for additional medications or prevent a trip to the hospital.

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

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


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).


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.