5-HIAA (24-hour urine)

5-hydroxyindoleacetic  acid

In patients with small-intestine carcinoid NETs decreasing levels may indicate a response to treatment. Diet and medications significantly affect 5-HIAA levels.

‡ Avoid eating avocados, bananas, cantaloupe, eggplant, pineapples, plums, tomatoes, hickory nuts, plantains, kiwi, dates, grapefruit, honeydew or walnuts for 48 hours prior to the start of urine collection. Coffee, alcohol and smoking should also be avoided during this period. Drugs such as acetaminophen, ephedrine, diazepam, nicotine, glyceryl guaiacolate (in some cough syrups) and phenobarbital can also increase 5-HIAA levels.
C-peptide/creatinine  ratio (urine) Used to evaluate how much insulin the pancreas is producing
Urinary fractionated metanephrines Used in confirming a diagnosis of pheochromocytoma
Urine catecholamine Used to evaluate levels of norepinephrine, epinephrine and other substances that can indicate the presence of pheochromocytoma


Biopsy All or part of a tumour is removed during a surgical procedure and then a sample of the tumour (biopsy specimen) is examined by a pathologist. Biopsy procedures are used to determine if a tumour is benign or malignant and to further analyze the characteristics of the tumour. Fine needle aspiration and core samples are two types of biopsies.
Calcitonin, fine needle aspiration biopsy (FNAB) Used to evaluate lymph nodes in individuals who have medullary thyroid carcinoma to determine if the cancer has spread
Electrolytes (fecal) Sometimes called a fecal osmolality test, a stool sample is evaluated for levels of electrolytes such as sodium, potassium and magnesium, to help determine the cause of chronic diarrhea
Electron microscopy Performed in the pathology lab on a sample of tumour tissue, neurosecretory granules may be identified that will help distinguish NETs – especially those of unknown primary origin – from other types of tumours
Immunoperoxidase staining Performed in the pathology lab on a sample of tumour tissue, analysis of synaptophysin, chromogranin, cytokeratin, epithelial membrane antigen and neutron-specific enolase tumour markers may help identify poorly differentiated NETs, especially those of unknown primary origin
KI-67 antigen A test that is performed on a sample of tumour tissue to determine how quickly the tumour cells are dividing and increasing in number (proliferating). The result of this test is sometimes referred to as the proliferation rate and – when evaluated alongside many other factors – it may provide an insight into how quickly a disease is progressing