What is the role of blood studies in the workup of paraneoplastic syndromes?

Updated: Jan 12, 2021
  • Author: Luigi Santacroce, MD; Chief Editor: Wafik S El-Deiry, MD, PhD  more...
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The complete blood cell count (CBC) may demonstrate anemia. This anemia may be the result of any of several different types of cancer, or it may be the result of different benign conditions. A microscopic study of the white blood cells is helpful for diagnosis of leukemia or lymphoma-related disorders. Hypereosinophilia is frequently observed in patients with Hodgkin lymphoma. A platelet count must be performed in any patient with symptoms of disseminated intravascular coagulation (DIC).

The erythrocyte sedimentation rate (ESR) is usually increased in patients with cancers. However, the ESR is a nonspecific marker for inflammation that is also elevated in a variety of disorders, including infections and rheumatologic disorders.

Blood enzymes may be altered, even in healthy individuals or those who have benign conditions. Increased plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydryogenase (LDH), and alkaline phosphatase (ALP) are commonly observed in patients with malignancies of the digestive system as well as in patients with bone or muscle injuries.

Protein electrophoresis of serum may demonstrate alterations of albumin levels and increased beta-globulins and gamma-globulins. Gamma-globulins are always increased in patients with autoimmune disorders, whether neoplastic or not.

Tumor markers are very useful for diagnosis of cancers that are clinically silent, but most markers are not specific for determining the origin of the cancer. For example, carcinoembryonic antigen (CEA) is increased in patients with tumors of the breast, lung, and digestive tract, as well as in patients who are heavy smokers.

Although prostate-specific antigen (PSA) is increased only in patients with prostatic disorders, it is increased in benign disorders (including inflammatory diseases) as well as in prostate cancer. Calculating free PSA as a percentage of total PSA can help differentiate benign from malignant disorders; the higher the percentage of free PSA (a level above 25% is considered normal), the lower the likelihood of cancer.

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