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N-methyl-D-aspartate Receptor Antibody
|Method||Semi-Quantitative Indirect Fluorescent Antibody|
|Container type||Gold top, CSF tube or sterile collection tube|
|Amount to Collect||
|Sample type||Serum or CSF|
|Min. Volume||0.15 mL serum or CSF|
|Processing notes||Aliquot and freeze. Ship to CB frozen. Order Mayo test code NMDCS (61516) for serum, or NMDCC (61513) for CSF.|
|Ref Lab Rejection Criteria||Contaminated, hemolyzed, or severely lipemic specimens|
|Stability||Room temperature 3 days, refrigerated 4 weeks, frozen 4 weeks|
|Turn around times||7-10 days|
|Reflex?||If positive, then an NMDA Antibody Titer is reported.|
|Additional information||Patients with NMDA-receptor antibody (targeting the GluN1 [NR1] subunit of this ionotropic glutamate receptor) have a fairly stereotyped neurological disorder, as described by Dalmau and colleagues. This disorder often develops in several stages. Prodromal symptoms include headache, fever, nausea, vomiting, diarrhea, or upper respiratory tract symptoms. Shortly afterwards, patients develop psychiatric symptoms and many initially come to the attention of psychiatrists. Anxiety, insomnia, fear, delusions, mania, and paranoia frequently occur; drug-induced psychosis may be suspected. Other behavioral changes include social withdrawal and stereotyped behavior. Amnesia and an unusual language disorder (noncortical aphasia) are common. The behavioral changes in children may be less specific and include temper tantrums and hyperactivity. Neurological disorders including seizures and dystonia are frequent, and may be the presenting symptom. After these initial symptoms, in both adults and children, decreased responsiveness ensues. Movement disorders include oro-lingual-facial dyskinesias, generalized chorea, oculogyric crisis, dystonia, and rigidity. Autonomic manifestations include hyperthermia, tachycardia, hypersalivation, hypertension, bradycardia, hypotension, urinary incontinence, and erectile dysfunction. Hypoventilation may necessitate extended ventilatory support (often months). Dissociative responses similar to those caused by NMDA-receptor antagonists (eg, phencyclidine or ketamine) have been observed (eg, resisting eye opening despite lack of response to painful stimuli).
The female:male ratio of patients is about 8:1. Overall, ovarian teratoma is encountered in approximately 50% of affected women. The most useful screening tests include magnetic resonance imaging (MRI) of pelvis, computed tomography (CT) scan, and pelvic and transvaginal ultrasound. The detection of teratoma is dependent on age and ethnic background; the younger the patient, the less likely that teratoma will be detected; black women are more likely to have teratoma than other ethnic groups. Only 2% have a neoplasm other than ovarian teratoma. Neoplasms documented in women include breast adenocarcinoma, ovarian neuroendocrine tumors, sex cord stromal tumor, pseudopapillary neoplasm of pancreas, neuroblastoma, and Hodgkin lymphoma. Neoplasia has been documented in 5% of men: testicular germ cell tumors or small-cell lung carcinoma.
Simultaneous testing of serum and cerebrospinal fluid (CSF) is recommended, because CSF is often more informative for NMDA-receptor antibody.
|CPT coding||86255-90 (86256-90 for reflex)|
|Last Updated||12/4/2014 10:30:07 AM|