TEST CATALOG ORDERING & RESULTS SPECIMEN HANDLING CUSTOMER SERVICE EDUCATION & INSIGHTS
Test Catalog

Test ID: GID2    
Autoimmune Gastrointestinal Dysmotility Evaluation, Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Investigating unexplained weight loss, early satiety, anorexia, nausea, vomiting, constipation or diarrhea in a patient with past or family history of cancer or autoimmunity

 

Directing a focused search for cancer

 

Investigating gastrointestinal symptoms that appear in the course or wake of cancer therapy, not explainable by recurrent cancer, metastasis or therapy; detection of autoantibodies on this profile helps differentiate autoimmune gastrointestinal dysmotility from the effects of chemotherapy

 

Detecting early evidence of cancer recurrence in previously seropositive patients who have a rising titer of 1 or more autoantibodies

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

If immunofluorescence assay (IFA) patterns suggest collapsin response-mediator protein-5-IgG (CRMP-5-IgG), then CRMP-5-IgG IFA or Western blot is performed at an additional charge.

 

If IFA patterns suggest amphiphysin antibody, then amphiphysin titer and/or amphiphysin immunoblot is performed at an additional charge.

 

If IFA pattern suggests ANNA-1 antibody, then ANNA-1 immunoblot and ANNA-2 immunoblot is performed at an additional charge.

 

If IFA pattern suggests PCA-1 antibody, then PCA-1 IFA and immunoblot is performed at an additional charge.

 

If IFA pattern suggests PCA-2 antibody, then PCA-2 IFA performed at an additional charge.

 

If IFA pattern suggests PCA-Tr antibody, then PCA-Tr IFA and immunoblot is performed at an additional charge.

 

If IFA pattern suggests NMDA-R, then NMDA-R cell-binding assay (CBA) and NMDA-R titer are performed at an additional charge.

 

If IFA pattern suggests AMPA-R, then AMPA-R CBA and AMPA-R titer are performed at an additional charge.

 

If IFA pattern suggests GABA-B-R, then GABA-B-R CBA and GABA-B-R titer are performed at an additional charge.

 

If IFA pattern suggests DPPX antibody, then DPPX CBA and DPPX titer are performed at an additional charge.

 

If acetylcholine (ACh) receptor binding antibody is above 0.02 nmol/L, then ACh receptor modulating antibodies and CRMP-5-IgG Western blot are performed at an additional charge.

 

If VGKC is above 0.00 nmol/L, then LGI1-IgG CBA and CASPR2-IgG CBA are performed at an additional charge.

 

See Autoimmune Gastrointestinal Dysmotility Evaluation Algorithm in Special Instructions.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Autoimmune gastrointestinal dysmotility (AGID) is a limited form of dysautonomia (also known as autoimmune autonomic ganglionopathy or neuropathy) that is sometimes a paraneoplastic disorder. Neoplasms most commonly found are lung cancer, thymoma, and miscellaneous adenocarcinomas. Diagnosis is confirmed by objective abnormalities on gastrointestinal (GI) motility studies (eg, gastric, small intestinal or colonic nuclear transit studies; esophageal, gastroduodenal, or colonic manometry or anorectal manometry with balloon expulsion). These disorders target autonomic postganglionic synaptic membranes and in some cases ganglionic neurons and autonomic nerve fibers, and may be accompanied by sensory small fiber neuropathy. Onset may be subacute or insidious. There may be additional manifestations of dysautonomia (eg, impaired pupillary light reflex, anhidrosis, orthostatic hypotension, sicca manifestations, and bladder dysfunction) or signs of other neurologic impairment. Autonomic reflex testing and a thermoregulatory sweat test are valuable aids in documentation of objective abnormalities.

 

The serological profile of AGID may include autoantibodies specific for onconeural proteins found in the nucleus, cytoplasm, or plasma membrane of neurons or muscle. Some of these autoantibodies are highly predictive of an underlying cancer. A commonly encountered autoantibody marker of AGID is the ganglionic neuronal alpha-3- acetylcholine receptor (alpha-3-AChR) autoantibody. The pathogenicity of this autoantibody was demonstrated in rabbits immunized with a recombinant extracellular fragment of the alpha-3-AChR subunit, and in mice injected with IgG from high-titered alpha-3-AChR autoantibody-positive rabbit or human sera. A direct relationship between antibody titer and severity of dysautonomia occurs in both experimental animals and patients. Patients with high alpha-3-AChR autoantibody values (>1.0 nmol/L) generally present with profound pandysautonomia, and those with lower alpha-3-AChR autoantibody values may have limited autoimmune dysautonomia or other neurological signs and symptoms.

 

Importantly, cancer is detected in 30% of patients with alpha-3-AChR autoantibody. Cancer risk factors include the patient's past or family history of cancer, history of smoking, or social and environmental exposure to carcinogens. Early diagnosis and treatment of the neoplasm favors less morbidity from the GI dysmotility disorder. The cancers recognized most commonly with alpha-3-AChR autoantibody include adenocarcinomas of breast, lung, prostate, and GI tract, or lymphoma. A specific neoplasm is often predictable when a patient's autoantibody profile includes other autoantibodies to onconeural proteins shared by neurons, glia, or muscle. Small-cell lung carcinoma is found in 80% of antineuronal nuclear antibody-type 1 (ANNA-1; anti-Hu)-positive patients and 23% of ANNA-1-positive patients have GI dysmotility. The most common GI manifestation is gastroparesis, but the most dramatic is pseudoobstruction.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Test ID

Reporting Name

Methodology

Reference Value

ARBI

ACh Receptor (Muscle) Binding Ab

Radioimmunoassay (RIA)

< or =0.02 nmol/L

GANG

AChR Ganglionic Neuronal Ab, S

RIA

< or =0.02 nmol/L

ANN1S

Anti-Neuronal Nuclear Ab, Type 1

Immunofluorescence assay (IFA)

<1:240

DPPIS

DPPX Ab IFA, S

IFA

 Negative

GD65S

GAD65 Ab Assay, S

RIA

< or =0.02 nmol/L

VGKC

Neuronal (V-G) K+ Channel Ab, S

RIA

< or =0.02 nmol/L

CCN

N-Type Calcium Channel Ab

RIA

< or = 0.03 nmol/L

STR

Striational (Striated Muscle) Ab, S

Enzyme-linked immunosorbent assay (ELISA)

 <1:120

 

Reflex Information:

Test ID

Reporting Name

Methodology

Reference Value

ARMO

ACh Receptor (Muscle) Modulating Ab

Live-cell assay (LCA)

0-20% (reported as __% loss of AChR)

AMPCS

AMPA-R Ab CBA, S

Cell-binding assay (CBA)

Negative

AMPIS

AMPA-R Ab IF Titer Assay, S

IFA

<1:120

AMPHS

Amphiphysin Ab, S

IFA

<1:240

AMIBS

Amphiphysin Immunoblot, S

IB

Negative

AN1BS

ANNA-1 Immunoblot, S

IB

Negative

AN2BS

ANNA-2 Immunoblot, S

IB

Negative

CS2CS

CASPR2-IgG CBA, S

CBA

Negative

CRMWS

CRMP-5-IgG Western Blot, S

Western Blot

Negative

CRMS

CRMP-5-IgG, S

IFA

<1:240

DPPCS

DPPX Ab CBA, S

CBA

Negative

DPPTS

DPPX Ab IFA Titer, S

IFA

<1:240

GABCS

GABA-B-R Ab CBA, S

CBA

Negative

GABIS

GABA-B-R Ab IF Titer Assay, S

IFA

<1:120

LG1CS

LGI1-IgG CBA, S

CBA

Negative

NMDCS

NMDA-R Ab CBA, S

CBA

Negative

NMDIS

NMDA-R Ab IF Titer Assay, S

IFA

<1:120

PC1BS

PCA-1 Immunoblot, S

IB

Negative

PCTBS

PCA-Tr Immunoblot, S

IB

Negative

PCABP

Purkinje Cell Cytoplasmic Ab Type 1

IFA

<1:240

PCAB2

Purkinje Cell Cytoplasmic Ab Type 2

IFA

<1:240

PCATR

Purkinje Cell Cytoplasmic Ab Type Tr

IFA

<1:240

 

Neuron-restricted patterns of IgG staining that do not fulfill criteria for ANNA-1, ANNA-2, PCA-1, PCA-2, or PCA-Tr may be reported as "unclassified anti-neuronal IgG." Complex patterns that include nonneuronal elements may be reported as "uninterpretable."

 

CRMP-5 titers lower than 1:240 are detectable by recombinant CRMP-5 Western blot analysis. CRMP-5 Western blot analysis will be done on request on stored serum (held 4 weeks). This supplemental testing is recommended in cases of chorea, vision loss, cranial neuropathy, and myelopathy. Call 1-800-533-1710 to request CRMP-5 Western blot.

Interpretation Provides information to assist in interpretation of the test results

Antibodies directed at onconeural proteins shared by neurons, muscle, and certain cancers are valuable serological markers of a patient's immune response to cancer. They are not found in healthy subjects and are usually accompanied by subacute symptoms and signs. It is not uncommon for more than 1 antibody to be detected. Three classes of antibodies are recognized (the individual antibodies from each class included in the profile are denoted in parentheses):

-Antineuronal nuclear autoantibody-type 1

-Neuronal and muscle cytoplasmic (collapsin response-mediator protein-5, glutamic acid decarboxylase, and striational)

-Plasma membrane cation channel (neuronal ganglionic  and muscle alpha-3-acetylcholine receptor, neuronal voltage-gated N-type calcium channel, neuronal voltage-gated potassium channel antibodies).

 

All of these autoantibodies are potential effectors of autoimmune gastrointestinal dysmotility.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Negative results do not exclude autoimmune gastrointestinal dysmotility or cancer.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Lennon VA, Sas DF, Busk MF, et al: Enteric neuronal autoantibodies in pseudo-obstruction with small cell lung carcinoma. Gastroenterology. 1991;100:137-142

2. Lucchinetti CF, Kimmel DW, Lennon VA: Paraneoplastic and oncological profiles of patients seropositive for type 1 anti-neuronal nuclear autoantibodies. Neurology. 1998;50:652-657

3. Vernino S, Adamski J, Kryzer TJ, Fealey RD, Lennon VA: Neuronal nicotinic ACh receptor antibody in subacute autonomic neuropathy and cancer-related syndromes. Neurology. 1998;50:1806-1813

4. Vernino S, Low PA, Fealey RD, Stewart JD, Farrugia G, Lennon VA: Autoantibodies to ganglionic acetylcholine receptors in autoimmune autonomic neuropathies. N Engl J Med. 2000;343:847-855

5. Dhamija R, Tan KM, Pittock SJ, Foxx-Orenstein A, Benarroch A, Lennon VA: Serological profiles aiding the diagnosis of autoimmune gastrointestinal dysmotility. Clin Gastroenterol Hepatol. 2008;6:988-992

6. McKeon A, Lennon VA, Lachance DH, Fealey RD, Pittock SJ: The ganglionic acetylcholine receptor autoantibody: oncological, neurological and serological accompaniments. Arch Neurol. 2009;66(6):735-741

7. Kraichely RE, Farrugia G, Castell DO, Castell DO, Lennon VA: Neural autoantibody profile of primary achalasia. Dig Dis Sci. 2010 Feb;55(2):307-311

Special Instructions Library of PDFs including pertinent information and forms related to the test