Blood tests are used to measure the number of blood cells in circulation and the levels of chemicals, enzymes, proteins, and organic waste products that are normally found in the blood. The levels of blood cells, such as red blood cells, white blood cells and platelets, may be low in patients receiving treatment for cancer. Also, the levels of some chemicals normally found in the blood may be either too high or too low as a result of the cancer or its treatment. There are two types of blood tests typically performed during cancer treatment: the complete blood count (CBC) and a blood chemistry panel.
Complete Blood Count (CBC)
The CBC measures the levels of the three basic blood cells: red blood cells, white blood cells, and platelets. In the United States, the CBC is typically reported in the format shown in Table 1 below. It is important to understand not only which blood counts are being tested, but also how those results are reported. You will want to pay careful attention to the results column, which shows any results that are normal and the flag column, which shows any results that are abnormal.
Table 1: CBC with results and reference interval
Test Result Flag Units Reference Interval
White Blood Count 1.5 L x 10-3/mL 4.0-10.5
Red Blood Count 3.50 L x 10-6/mL 4.70-6.10
Hemoglobin 10.8 L g/dL 14.0-18.0
Hematocrit 31.1 L % 42.0-52.0
Platelets 302 x 10-3/mL 140-415
Polys 23 L % 45-76
Lymphs 68 H % 17-44
Monocytes 7 % 3-10
Eos 2 % 0-4
Basos > % 0.2
Polys (absolute) .34 L x 10-3/mL 1.8-7.8
Lymphs (absolute) 1.0 x 10-3/mL 0.7-4.5
Monocytes (absolute) 0.1 x 10-3/mL 0.1-1.0
Eos (absolute) 0.1 x 10-3/mL 0.0-0.4
Basos (absolute) 0.0 x 10-3/mL 0.0-0.2
Result column The result column shows counts that fall within the normal range.
Flag column The flag column shows counts that are lower (“L”) or higher (“H”) than the normal range.
Reference interval (or reference range) column The reference interval shows the normal range for each measurement
White blood cells
Absolute neutrophil count Neutrophils are the main white blood cell for fighting or
Red blood cells Red blood cells carry oxygen from the lungs to the rest of the body. The above CBC report indicates that the patient has a red cell count of 3.5, which is lower than the normal range of 4.70-6.10, and therefore, shown in the flag column
Hemoglobin (Hb or Hgb) Hemoglobin is a protein in the red cell that carries oxygen. The above CBC report indicates that the patient’s Hb count is 10.8, which is
Blood Chemistry Panel
The blood chemistry panel measures the levels of chemicals, enzymes, and organic waste products that are normally found in the blood. The results of a blood chemistry panel are typically reported with the name of the substance, the result, and the reference interval, as shown in Table 2. The reference interval is the normal range for that laboratory. Reference intervals may vary between laboratories. Substances that are typically measured in cancer patients are as follows:
Table 2: Sample blood chemistry panel with results and reference interval
Test Result Units Reference interval
Albumin 3.9 g/dL 3.5-5.0
ALT (SGPT) 19 IU/L 6-31
AST (SGOT) 21 IU/L 11-36
Alkaline phosphatase 57 mg/dL 38-126
Total billirubin 0.8 mg/dL 0.2-1.3
BUN 11 mg/dL 7-17
Calcium 9.2 mg/dL 8.4-10.2
Chloride 101 mmol/L 98-107
Creatinine 0.8 mg/dL 0.7-1.2
Glucose 98 mg/dL 65-105
Lactate dehydrogenase (LDH) 149 IU/L 100-250
Magnesium 0.89 mmol/L 0.65-1.05
Potassium 4.0 mmol/L 3.6-5.0
Sodium 141 mmol/L 137-145
Total protein 7.0 g/dL 6.3-8.2
Uric Acid 301 mmol/L 227-367/467
Albumin is the most prevalent protein in the blood. It is synthesized in the liver and removed from circulation by the kidney, which causes it to be excreted in the urine. Albumin is often measured in order to detect liver damage or kidney damage, either of which may be a side effect of cancer or cancer treatment.
Alanine aminotransferase (ALT) is an enzyme in the liver that rearranges the building blocks of proteins. It is released from damaged liver cells. Cancer patients may experience liver damage as a side effect of some cancer treatments or due to spread of cancer to their liver. ALT may also be referred to as SGPT (serum glutamic pyruvic transferase.)
Aspartate aminotransferase (AST) is an enzyme in the liver that rearranges the building blocks of proteins. It is released from damaged liver cells. Cancer patients may experience liver damage as a side effect of some cancer treatments or due to spread of cancer to their liver. AST may also be referred to as SGOT (serum glutamic oxaloacetic transaminase.)
Alkaline phosphatase is an enzyme is that involved in bone growth. It is processed in the liver and excreted into the digestive tract in the bile. A higher than normal amount of alkaline phosphatase indicates bone or liver problems. In cancer patients, elevated alkaline phosphatase may indicate that cancer has spread to the bones or that liver damage, possibly due to some chemotherapy drugs, has caused problems with bile excretion.
Billirubin is a substance that is formed from broken down red blood cells. It becomes part of bile, which is produced by the liver. A build-up of bilirubin can cause jaundice and may be measured to test for liver or bile duct function, which may be compromised if there is cancer in the liver or if there is liver damage. Some chemotherapy drugs may cause liver damage.
BUN (blood urea nitrogen) is a part of urea, the waste product that is left over from the breakdown of protein. Urea circulates in the blood until it is filtered out by the kidneys and excreted in the urine. If the kidneys are not functioning properly, there will be excess urea in the bloodstream, resulting in higher than normal BUN levels. Cancer patients may have elevated BUN if they have been treated with certain chemotherapy drugs that may cause kidney damage.
Calcium is a chemical that
Lactate dehydrogenase (LDH) is involved in producing energy and is released from damaged cells
Magnesium is a chemical
Uric Acid is the
Additional results that are sometimes included in
Table 3: Measures of the blood’s clotting capacity
Test Result Units Reference interval
aPTT 3.9 seconds 24-35
Prothrombin time (PT)/INR 19 seconds 24-35
Activated Partial Thromboplastin Time (aPTT) is a measure of bleeding and clotting and is used to evaluate unexplained bleeding or monitor heparin treatment. Heparin is a drug that is administered to increase the clotting capacity of a patient’s blood. Some cancer patients may receive heparin as treatment for a low platelet count, or thrombocytopenia, which is a side effect of some cancer treatments. This condition can lead to more easy bruising and bleeding.
Prothrombin time (PT) is the most common way to express the clotting capacity of blood. PT results are reported as the number of seconds the blood takes to clot when mixed with a thromboplastin reagent. The International Normalized Ratio (INR) was created by the World Health Organization because PT results can vary depending on the thromboplastin reagent used. The INR is a conversion unit that takes into account the different sensitivities of thromboplastins. The INR is widely accepted as the standard unit for reporting PT results. Cancer patients may have an abnormally low PT/INR due to a lower than normal platelet count. Platelets are the components of blood that stop bleeding by clotting the blood. A low platelet count, also called thrombocytopenia, and a low PT may lead to more frequent bruising and bleeding.