Interpretive Handbook

Test 8877 :
Beta-Human Chorionic Gonadotropin, Quantitative, Spinal Fluid

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

Human chorionic gonadotropin (hCG) is synthesized during pregnancy by syncytiotrophoblast cells. hCG may also be produced by neoplastic cells of testicular tumors (seminomas or nonseminomas), ovarian germ cell tumors, gestational trophoblastic disease, choriocarcinoma and various nontrophoblastic tumors, including breast, ovarian, pancreatic, cervical, gastric, and hepatic cancers.

 

Measurement of hCG is used as an adjunct in the diagnosis of germ cell tumors. The presence of hCG in cerebrospinal fluid (CSF) is suggestive of tumor presence. Pure germinomas are associated with low hCG concentrations in both serum and CSF. A subset of nongerminomatous germ cell tumors contains syncytiotrophoblastic giant cells. These tumors are associated with moderately increased hCG concentrations (<1000 IU/L) in the serum and/or CSF, and the survival rate in patients suffering these tumors is worse than that of patients with pure germinomas. In contrast, choriocarcinomas, another subset of nongerminomatous germ cell tumors, are associated with very high hCG concentrations (>1000 IU/L) in both serum and CSF. Quantification of the hCG in CSF can be important in guiding treatment and monitoring response to treatment of these tumors.

 

The combination of the specific antibodies used in the Roche Beta HCG immunoassay recognize the holo-hormone, "nicked" forms of hCG, the beta-core fragment, and the free beta-subunit.

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

As an aid in the diagnosis of brain metastases of testicular cancer or extragonadal intracerebral germ cell tumors

Interpretation Provides information to assist in interpretation of the test results

Elevated levels of human chorionic gonadotropin in spinal fluid indicate the probable presence of central nervous system metastases or recurrence of tumor in patients with germ cell tumors, including patients with testicular cancer or choriocarcinoma.

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

Slight elevations of human chorionic gonadotropin (hCG) in cerebrospinal fluid (CSF) may occur in non-neoplastic diseases.

 

In pregnancy, elevations of hCG in CSF may be observed due to blood contamination during CSF collection.

 

Values obtained with different assay methods or kits may be different and cannot be used interchangeably.

 

Test results cannot be interpreted as absolute evidence for the presence or absence of malignant disease.

 

Measurement of hCG in spinal fluid should not be relied upon exclusively to determine the presence of central nervous system metastases in patients with germ cell tumors.

 

Specimens should not be collected from patients receiving therapy with high biotin doses (ie, >5 mg/day) until at least 8 hours following the last biotin administration.

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.

<1.0 IU/L

Clinical References Provides recommendations for further in-depth reading of a clinical nature

1. Chenglin T, Jiatang Z, et al: CSF and serum hCG in patients without gestational and neoplastic hCG-secretion. Scand J Clin Lab Invest Suppl. 2011;71:264-268

2. Chenglin T, Ruozhuo L, et al: Re-evaluation of the significance of cerebrospinal fluid human chorionic gonadotropin in detecting intracranial ectopic germinoas. J Clin Neurosci 2011;18:223-226

3. Gonzalez-Sanchez V, Pico Alfonso A M, et al: Validation of the human chorionic gonadotropin immunoassay in cerebrospinal fluid for the diagnostic work-up of neurohypophyseal germinomas. Ann Clin Biochem 2011;48: 433-437


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