Clinical Significance:
Octreotide (Sandostatin,® Novartis Pharmaceutical Company) is used for the control of symptoms associated with functional neuroendocrine tumors. Frequent measurement of the octreotide levels may be useful in guiding therapy in patients with poorly controlled symptoms or those patients experiencing tumor growth during LAR therapy. Octreotide levels in blood need to be in a specific range to be effective. Measuring octreotide immediately prior to the monthly LAR injection will determine trough levels of the drug in your blood.
Reference Range:
Long-acting repeatable (LAR) dose-response levels: mean octreotide level ± 2 SD
for patients on octreotide LAR for 3 or more months (steady-state). The following
represent trough levels measured immediately before an injection of LAR.
10 mg/month: 1153 ± 748 pg/mL
20 mg/month: 2518 ± 1020 pg/mL
30 mg/month: 5241 ± 3004 pg/mL
60 mg/month: 10,926 ± 5530 pg/mL
Procedure:
Octreotide is measured by direct radioimmunoassay. There is no cross-reactivity with native somatostatin-14 or somatostatin-28. The also is no cross-reactivity with lanreotide, and this test should not be used to measure blood levels of this drug.
Patient Preparation:
This test is useful only for those patients being treated with octreotide acetate. No special preparation is needed for this test. For optimal results, blood for this test should be drawn immediately before the patient's next injection of octreotide LAR
(trough levels).
Specimen Collection:
Collect 3 mL serum or EDTA plasma and separate as soon as possible. Octreotide is stable at room temperature for 3 days. Specimens can be stored at room temperature, refrigerated, or frozen in dry ice. Minimum specimen size is 1 mL.
Special Specimens:
For tumor/tissue and various fluids (e.g., CSF, peritoneal fluid, synovial fluid) contact ISI for requirements and special handling instructions.
Shipping Instructions:
Specimens can be shipped at ambient temperature, refrigerated, or frozen in dry ice.
References:
1. Woltering EA, Mamikunian PM, Zietz S, et al. The effect of octreotide LAR dose and weight on octreotide blood levels in patients with neuroendocrine tumors. Pancreas. 31(4):392-400, 2005.
Clinical Significance:
Oxytocin is one of the two major posterior pituitary hormones. The nine amino acid peptide has potent uterus contracting and milk ejecting properties, achieved by stimulating contraction of myoepithelial cells in the mammary gland. Oxytocin given to pregnant women increases the frequency and intensity of uterine contraction. Oxytocin is synthesized and secreted together with one of the Neurophysins, which acts as a carrier protein for Oxytocin. Oxytocin is structurally very similar to Vasopressin. It possesses luteolytic action. It increases to a peak at ovulation and is lowest in the late luteal phase. Women on Estrogens and oral contraceptives have increased levels of both Oxytocin and Estrogen-stimulated Neurophysin. Levels of Oxytocin are suppressed by stress.
Reference Range:
25 – 150 pg/ml
Procedure:
Oxytocin is measured by direct radioimmunoassay.
Patient Preparation:
Patient should not be on Steroid, ACTH, Gonadotropin, or Estrogen medications, if possible, for at least 48 hours prior to collection of specimen.
Specimen Collection:
3 ml serum or EDTA plasma should be collected and separated as soon as possible. Freeze specimens immediately after separation. Minimum specimen size is 1 ml.
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. SEF Guldenaar, DC Wathes, and BT Pickering. Immunocytochemical Evidence for the Prescence of Oxytocin and Neurophysin in the Large cells of the Bovine Corpus Luteum. Cell Tissue Research 237: 349, 1984.
2. RD Leake, RE Weitzman, TH Glatz, and DA Fisher. Plasma Oxytocin Concentration in Men, Nonpregnant Women, and Pregnant Women before and during Spontaneous Labor. Journal of Clinical Endocrinology and Metabolism 53: 730, 1981.
*Research Basis only.
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