Clinical Significance

   Monitoring patients for retained products of conception. Aiding in the diagnosis of gestational trophoblastic disease (GTD), testicular tumors, ovarian germ cell tumors, teratomas, and, rarely, other human chorionic gonadotropin (hCG)-secreting tumors.

   Serial measurement of hCG following treatment for:

       Monitoring therapeutic response in GTD or in hCG-secreting tumors

       Detecting persistent or recurrent GTD or hCG-secreting tumors

Specimen

   Serum

Stability

   Refrigerated (preferred) : 7 days

   Frozen : 90 days

   Ambient : 7 days

Reference Range

   Men : < 2 mIU/ml

   Women : < 2 mIU/ml

   Non pregnant premenopausal women : ≤ 1 mIU/ml

   Healthy postmenopausal women : ≤ 7 mIU/ml

Interpretation

   In non-pregnant women, hCG is normally undetectable in blood and urine. During early pregnancy, the amount of hCG in the blood doubles every two to three days. Ectopic pregnancies usually have a longer doubling time. Those with failing pregnancies will also frequently have a longer doubling time or may even show falling hCG concentrations. hCG concentrations will drop rapidly following a miscarriage. If hCG does not fall to undetectable levels, it may indicate remaining hCG-producing tissue that will need to be removed.

   hCG analysis is combined with other tests as part of the prenatal screening program for Down’s syndrome. The results of the combined tests are used to assess a woman’s risk of having a baby affected by Down’s syndrome.

   hCG is also used to monitor treatment in patients with trophoblastic disease and to detect recurrent disease after treatment is complete. During therapy, a falling hCG level generally indicates that a tumour is responding to treatment, while rising levels may indicate that a tumour is not responding to therapy. Increased hCG levels after treatment may indicate a recurrence of disease.

Limitation

   Transient elevations of serum hCG can occur following chemotherapy in patients with susceptible tumors, due to massive tumor cell lysis; these transient elevations should not be confused with tumor progression. Normal serum levels of hCG do not always exclude tumor persistence since tumors may undergo transition to differentiated teratomas, which may not produce hCG.