Human chorionic gonadotropin ( human chorionic gonadotropin ) is a chemical created by trophoblast tissue, weave typically found in early on embryo and which will finally be part of the placenta. Measuring human chorionic gonadotropin levels can be helpful in identifying a normal pregnancy, pathological pregnancy, and can besides be utilitarian following an abort pregnancy. There is besides a benefit in measuring human chorionic gonadotropin in a variety of cancers including choriocarcinoma and extra-uterine malignancies .

Etiology and Epidemiology

Human chorionic gonadotropin is a hormone produced chiefly by syncytiotrophoblastic cells of the placenta during pregnancy. The hormone stimulates the principal luteum to produce progesterone to maintain the pregnancy. Smaller amounts of human chorionic gonadotropin are besides produced in the pituitary gland, the liver, and the colon. [ 1 ] As previously mentioned, certain malignancies can besides produce either hCG or hCG-related hormone. trophoblastic cancers ( hydatidiform mole, choriocarcinoma, and microbe cell tumors ) are associated with high serum levels of hCG-related molecules. The hormone itself is a glycoprotein composed of two subunits, the alpha and beta subunits. [ 1 ] There are multiple forms found in the serum and urine during pregnancy including the entire hormone and each of the free subunits. HCG is primarily catabolized by the liver, although about 20 % is excreted in the urine. The beta fractional monetary unit is degraded in the kidney to make a core fragment which is measured by urine human chorionic gonadotropin tests .

Specimen Requirements and Procedure

Urine Testing

  • urine should not be collected after the patient has been drinking a boastfully measure of fluid, as a diluted specimen may result in a falsely minus test. [ 2 ]
  • blood in the urine may cause a delusive plus test consequence .

Serum Testing

  • peripheral rake can be obtained for a serum human chorionic gonadotropin test .

Diagnostic Tests

serum tests for human chorionic gonadotropin are immunometric assays. This means that they use 2two antibodies that bind to the human chorionic gonadotropin atom, a fixed antibody and a radiolabeled antibody which adhere to unlike sites on the molecule, sandwiching and immobilize the atom to make it detectable. [ 3 ] Assays involve washing aside the overindulgence serum components and measuring the sum of remaining labeled human chorionic gonadotropin to give a quantitative result. There are more than 100 different assays commercially available which results in significant unevenness in reported values. Urine assays are like, although many detect total human chorionic gonadotropin levels greater than 20 mIU/mL. [ 4 ] many nonprescription urine pregnancy tests do not detect hyperglycosylated human chorionic gonadotropin, which accounts for most of the human chorionic gonadotropin in early pregnancy, resulting in a broad range of sensitivities of these tests. Serum test is much more sensitive and specific than urine test. Urine testing, however, is more commodious, low-cost, comfortable for patients, has a fast turnaround ( 5 to 10 minutes ), and does not require a aesculapian prescription .

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Testing Procedures

Urine Testing

  • urine is placed in or on a intend receptacle ( most commercially available and medical point of caution tests )
  • An indicator ( typically a tinge tune or symbol ), along with a control, will appear if the examination is positive
  • An detached restraint line/symbol will be discernible if the test is negative

Serum Testing

  • Serum human chorionic gonadotropin test is performed in a testing ground equipped with the proper machinery and uses a peripheral blood sample
  • If a hook effect/gestational trophoblastic disease is suspected, the lab should perform a dilution prior to testing

Interfering Factors

There are multiple reasons why an human chorionic gonadotropin test ( serum or urine ) may have a false report. While rare, faithlessly cocksure human chorionic gonadotropin tests can result in unnecessary medical care and/or irreversible surgical procedures. False negatives may be equally concerning and result in a delay in wish or diagnostic evaluation. potential causes of assumed results are listed and concisely discussed. Serum False Positives (1/1000 to 1/10,000) [ 5 ]

  • Ectopic production of human chorionic gonadotropin ( hydatidiform mole, choriocarcinoma, and source cell tumors, [ 6 ], in addition to multiple myeloma, stomach, liver, lung, bladder, pancreatic, front, colon, cervical, and endometrial cancers ) [ 7 ] [ 8 ] [ 9 ] [ 10 ] [ 11 ]
  • Heterophile antibodies ( autoantibodies and antibodies formed after exposure to animal products that interact with the assay antibodies ) [ 12 ] [ 13 ]
  • arthritic factors ( can bind the antibodies in the assay deoxyadenosine monophosphate good )
  • IgA insufficiency [ 14 ]
  • Chronic nephritic bankruptcy or ESRD on hemodialysis ( rare ) [ 15 ]
  • red blood cell or plasma transfusion of blood with human chorionic gonadotropin in it have been reported
  • exogenous human chorionic gonadotropin preparations for weight personnel casualty, assisted reproduction, doping [ 16 ]

Serum False Negatives

  • early measurement after conception
  • “ hook effect ” can occur when human chorionic gonadotropin levels are about 500,000 mIU/mL. [ 17 ] This is because there are indeed many human chorionic gonadotropin molecules that they saturate both the tracer and the antibodies individually, which does n’t allow for the sandwich of the tracer-hCG-antibody required for the measurement. This means that all of the complexes are washed away, giving a false-negative result. If gestational trophoblastic disease is suspected, the lab should perform a dilution prior to testing .
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Urine False Positives

  • blood or protein in the urine
  • Human error in solution interpretation
  • Ectopic production of human chorionic gonadotropin
  • exogenous human chorionic gonadotropin
  • Drugs ( aspirin, carbamazepine, methadone, high urinary ph and seminal fluid ) [ 18 ]

Urine False Negatives

  • early measurement after conception
  • Dilute urine specimen [ 2 ]
  • “ hook effect ” as discussed above

Results, Reporting, Critical Findings

HCG levels are reported in milli-international units of human chorionic gonadotropin hormone per milliliter of rake, or mIU/mL. International unit per liter ( IU/L ) may besides be used. Urine human chorionic gonadotropin testing is qualitative, reporting a positive or negative result. The assays detect human chorionic gonadotropin levels typically starting at 20 to 50 ( reportedly vitamin a low as 6.3 to 12.5 ) [ 19 ] mIU/mL, corresponding to levels at approximately 4 weeks post-conception. Serum assays can measure beta-hCG adenine abject as 1 to 2 mIU/mL .

Clinical Significance

Pregnancy HCG is an important hormone in pregnancy, and its clinical utility is chiefly centered around its signal detection in early pregnancy, along with serial measurement during pregnancy and pregnancy-related complications. Levels of human chorionic gonadotropin can vary widely between women with normal pregnancies. typically, serum and urine concentrations of human chorionic gonadotropin emanation exponentially in the beginning trimester of pregnancy, doubling about every 24 hours during the first 8 weeks. The top out is normally about 10 weeks of gestation and then levels decrease until about the 16th week of pregnancy where they remain fairly changeless until condition. [ 3 ] Patients who have hCG levels that tableland prior to 8 weeks or that fail to double normally have a nonviable pregnancy, whether intra-uterine or extra-uterine. Extra-uterine ( ectopic ) pregnancies normally have a rate-of-rise that is abject without the distinctive double over. however, given the large range of normal human chorionic gonadotropin levels and inconsistent rates-of-rise of this hormone, checking serum levels is typically paired with ultrasound evaluation to improve sensitivity and specificity. [ 20 ] restitution of human chorionic gonadotropin to zero following manner of speaking or termination of pregnancy ranges from 7 to 60 days. [ 21 ] Trending the fall of human chorionic gonadotropin levels can be authoritative in end point of molar pregnancies and besides following the end point of convention or ectopic pregnancies to be assured that the therapy has been successful. It noteworthy that there are many different combinations of antibodies used in commercial assays. This results in heterogenous results with ampere much as a 50-fold remainder in immunoassay results. [ 3 ] This is clinically relevant, particularly when comparing results from unlike laboratories in unlike facilities/hospitals when examining moo values following pregnancy result or trophoblastic disease. Gestational Trophoblastic Disease detection of human chorionic gonadotropin is besides utilitarian in the evaluation of trophoblastic disease, including complete and overtone hydatidiform mole, postmolar tumor, gestational choriocarcinoma, testicular choriocarcinoma, and placental site trophoblastic disease. All of these entities produce human chorionic gonadotropin, varying levels of which are reported on commercial assays. A full human chorionic gonadotropin horizontal surface of greater than 100,000 mIU/mL in early pregnancy, for model, is highly indicative of a complete hydatidiform mole, [ 22 ] although many normal pregnancies may reach this flat at their acme around weeks 8 to 11 of gestation. Precise human chorionic gonadotropin measurements are authoritative to assess the tumor mass, the successful discussion of malignancy, and to test for recurrence or doggedness of disease. [ 6 ]

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Non-Pregnant Patients HCG in the serum increases with senesce in nonpregnant women. A cut off of 14 mIU/mL has been suggested for manipulation in interpreting results in women over the old age of 55. In all nonpregnant patients, testicular cancer, ovarian cancer, bladder cancer, or early malignity should be evaluated as a beginning of persistently positive human chorionic gonadotropin examination .

Enhancing Healthcare Team Outcomes

Knowing the utility and variability of different human chorionic gonadotropin assays is clinically relevant to a wide range of medical providers. False positive and false damaging test has a large affect on patient care. All providers in a patient care team should be mindful of common limitations in test, for exercise, urine assay false positives with hematuria, delusive negatives with dilute urine, along with more obscure but inactive very relevant causes of inaccurate testing. Interpreting results that may be false should be undergo with care to help prevent unnecessary screen and treatment. [ 23 ] ( Level V ) Collaboration, shared decision make, and communication are critical elements in commodity patient care .

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Category : Nutrition