Chronic Diarrhea: Diagnosis and Management

Lawrence R. Schiller; Darrell S. Pardi; Joseph H. Sellin


Clin Gastroenterol Hepatol. 2017;15(2):182-193. 

In This Article

What Is the Utility of Blood Tests?


16. Routine blood tests may provide clues to etiology and fluid and electrolyte status. Other blood tests should be obtained only when demanded by the clinical presentation. (2c)

17. Because of the rarity of peptide-secreting tumors, measurement of circulating peptide levels should be reserved for very select patients. (1b)

Routine blood tests (complete blood count and metabolic profile) can be used to evaluate fluid and electrolyte balance and nutritional sufficiency. Additional testing for entities such as CD, hyperthyroidism, amyloidosis, immunodeficiency, and mastocytosis can be considered on the basis of specific elements of each case.

Hormone-secreting tumors are rare causes of secretory diarrhea.[52] In patients with classic tumor syndromes, evidence of tumor, or severe chronic diarrhea that remain undiagnosed after a detailed evaluation, measurement of serum chromogranin, gastrin, vasoactive intestinal polypeptide, or calcitonin levels, and/or urinary 5-hydroxyindoleacetic acid can be considered. However, because of the rarity of these tumors and low pretest probability of these disorders, most positive tests end up being false-positive results.[52]