Clinical Significance:
Substance P is an 11 amino acid peptide originally detected in the brain and gut, but later detected in skin, sensory organs, respiratory tract, genitourinary tract, and exocrine glands. It is a member of the Tachykinin family that includes Substance K, Neuromedin K, Physalaemin, and Eledoisin. Substance P increases amylase release in the pancreas and stimulates accumulation of cGMP. It suppresses hepatic bile. Substance P is a potent releasing agent of Histamine and reduces sensitivity of the pancreas to secretory stimulation without affecting secretion of bicarbonate, and reduces pancreatic response to acidification without affecting Secretin levels. Substance P is capable of causing flushing, hypotension, bronchoconstriction and diarrhea. It has been detected in elevated levels in the blood and tissue of patients with Carcinoid Tumor of the gut and Medullary Carcinoma of the Thyroid.
Reference Range:
40 – 270 pg/ml
Procedure:
Supstance P is measured by direct radioimmunoassay.
Patient Preparation:
Patient should be fasting 10 – 12 hours prior to collection of specimen. Antacid medication or medications that may affect intestinal motility should be discontinued, if possible, for at least 48 hours prior to collection.
Specimen Collection:
Collect 10mL blood directly into ISI’s Z-tube Preservative and separate as soon as possible. Freeze plasma immediately after separation. Special Z-tube Preservatives are available from ISI. Minimum specimen size is 1mL.
Important Precaution:
Specimens for this assay must be collected using the Z-tube). Specimens must be shipped frozen; specimens are not stable at refrigerated or room temperatures. No other specimens are acceptable.
Special Specimens:
For tumor/tissue and various fluids (i.e. CSF, peritoneal, synovial, etc.) contact the Institute for requirements and special handling.
Shipping Instructions:
Ship specimens frozen in dry ice.
References:
1. Aronin N, Leeman SE, Clements RS Jr. Diminished flare response in neuropathic diabetic patients: comparison of effects of substance P, histamine and capsaicin. Diabetes.1987;Oct;36(10):1139-43
2. Aronin N, Coslovsky R, Chase K. Hypothyroidism increases substance P concentrations in the heterotropic anterior pituitary. Endocrinology.1988;Jun;122(6):2911-4.
3. Vinik AI, Gonin J, England BG, et al. Plasma substance-P in neuroendocrine tumors and idiopathic flushing: the value of pentagastrin stimulation tests and the effects of somatostatin analog.J Clin Endocrinol Metab. 1990;70(6):1702-9.