Bloodwork should be fasting for 12 hours for the following tests:
C-peptide (14 hours)
Pancreatic polypeptides

ACTH Helps determine the cause of high and low cortisol levels
Alpha subunit pituitary marker Helps identify pituitary and non-pituitary tumours
B12 Helps identify certain types of anemia
C-peptide (serum) Part of a diagnostic evaluation of blood glucose and insulin
Calcitonin Diagnosis and follow-up of medullary thyroid carcinoma
Chromogranin A Because of its wide distribution in neuroendocrine tissues, this test can be a useful diagnostic marker for NETs. Note that chromogranin A levels may be falsely elevated PPI medications are being used.
Complete blood count A basic screening tool for many blood disorders
Cortisol Evaluates adrenal insufficiency, particularly the diagnosis of Cushing syndrome
Electrolytes (serum) Tests levels of sodium, potassium, chloride, bicarbonate (and other substances) to identify a range of clinical disorders
Follicle Stimulating Hormone Useful for diagnosing pituitary disorders and evaluating levels of sex hormones
Gastrin Used to investigate levels of stomach acid (gastrin), including suspected cases of Zollinger-Ellison syndrome/gastrinoma. Note that gastrin levels may be falsely elevated if PPI medications are being used.
GH-RH (Growth hormone releasing hormone) Used to evaluate the ability of the pituitary gland to release growth hormone
Glucagon Evaluates levels of glucagon, produced by pancreatic cells, which help to maintain blood glucose levels
Gn-RH (gonadotrophin releasing hormone) Used to tell the difference between primary and secondary hypogonadism, a condition in which the sex glands produce few, if any, hormones
Insulin-like Growth Factor (IGF-1) Increased levels of IGF-1 are frequently associated with pituitary tumours
Insulin Used to help diagnose insulinoma when used in conjunction with proinsulin and C-peptide measurements
Insulin/glucose ratio Used as a screening test for insulin resistance (how well the pancreatic cells respond to insulin)
Luteinizing Hormone (LH) Used to help diagnose pituitary disorders
Neurokinin A (substance K) A test that evaluates circulating levels of neurokinin A, high levels of which may indicate a poor prognosis in certain types of NETs
Not yet available in Canada. Available in the U.S.†
Pancreastatin A new test that uses measurements of pancreastatin to potentially identify NETs at an earlier stage with greater clarity
Not yet available in Canada. Available in the U.S.†
Pancreatic polypeptide Used for detection of pancreatic NETs
Plasma catecholamine Used to help diagnose pheochromocytoma and paraganglioma. Also used for the diagnosis and follow-up of   neuroblastoma and related tumours.
Plasma fractionated metanephrines The gold standard test used in the diagnosis of pheochromocytoma
Proinsulin Used as part of the diagnostic work-up of suspected insulinoma
Prolactin Used in the evaluation of pituitary tumours, menstrual disorders, abnormal milk production, infertility and low sex hormones
PTH-related peptide Used as part of a diagnostic work-up in patients who may have high calcium levels resulting from cancer
Somatostatin Used to evaluate the amount of somatostatin in the blood in suspected pancreatic NETs
Thyroid Stimulating Hormone (TSH) Used to evaluate thyroid function and/or symptoms of hyperthyroidism or hypothyroidism, or to evaluate the function of the pituitary gland
Vasoactive Intestinal Polypeptide (VIP) Used to evaluate vasoactive intestinal polypeptide producing tumours in patients who are experiencing chronic diarrhea