Sorted By Test Name - Mayo Medical Laboratories

MDCG
86880
MORP
83132
SPSM
9184
Monospecific Direct Coombs IgG, Blood
Clinical Information: IgG antibody may be present on patient or donor (transfused) RBCs and may
cause hemolysis. The antibodies may be directed against self-antigens (autoimmune hemolysis), maternal
antigens (hemolytic disease of the newborn), donor antigens (eg, alloimmune transfusion reaction), or
drugs. The presence of in vivo coating of RBC with IgG can be demonstrated by the direct antiglobulin
(Coombs) test.
Useful For: Detecting antibodies bound to RBC Investigation of hemolytic anemia
Interpretation: The presence or absence of IgG is used in conjunction with other testing and clinical
data to aid in the characterization of Hemolysis as immune-mediated. Possible causes include
autoimmune hemolytic anemia, drug-induced hemolysis, hemolytic disease of the newborn, and
alloimmune reactions to recently transfused RBC.
Reference Values:
Negative
If positive, reaction is graded (positive 1+ to 4+).
Morphine, Unconjugated, Serum
Clinical Information: Morphine interacts primarily with mu-opioid receptor to mediate its effects,
but also shows some affinity for kappa-opioid receptor.(1) Its major metabolites are glucuronide
conjugates including: inactive morphine-3-glucuronide (M3G, approximately 60%), active
morphine-6-glucuronide (M6G, approximately 10%), and a small amount of
morphine-3,6-diglucuronide.(2, 3) The enzyme UDP-glucuronosyltransferase-2B7 (UGT2B7) is primarily
responsible for morphine glucuronidation.(2)
Useful For: Monitoring morphine therapy Routine drug monitoring is not indicated in all patients.
Compliance monitoring is indicated in patients who are being treated for acute pain requiring excessive
dose. Assessing toxicity
Interpretation: The minimal effective peak serum concentration of unconjugated morphine for
analgesia is 20 ng/mL. Peak therapeutic serum concentrations of 70 ng/mL to 450 ng/mL occur 30
minutes after intravenous dose, 1 hour after intramuscular or subcutaneous dose, or 2 hours after oral
dose. Patients continuously administered morphine develop tolerance; they can tolerate serum
concentrations up to 1,500 ng/mL. Death may be associated with serum total morphine >700 ng/mL in the
nontolerant subject.(4)
Reference Values:
Therapeutic: 70-450 ng/mL
Tolerant patients: 700 ng/mL
Clinical References: 1. Gutstein HB, Akil H: Opioid analgesics. In Goodman & Gilman's The
Pharmacological Basis of Therapeutics, 11th edition. Edited by LL Brunton, JS Lazo, KL Parker. New
York, McGraw-Hill Book Company, 2006, pp 547-590; available from URL:
http://www.accessmedicine.com/content.aspx?aID=940653 2. Coffman BL, Rios GR, King CD, et al:
Human UGT2B7 catalyzes morphine glucuronidation. Drug Metab Dispos 1997;25:1-4 3. Wittwer E,
Kern SE: Role of morphine's metabolites in analgesia: concepts and controversies. AAPS J 2006 May
26;8(2):E348-352 4. Baselt RC: Morphine. In Dispositition of Toxic Drugs and Chemical in Man. 8th
edition. Edited by RC Baselt, Foster City, CA, Biomedical Publications, 2008, pp 1057-1061
Morphology Evaluation (Special Smear)
Clinical Information: Under normal conditions, the morphology and proportion of each blood cell
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