hCG - plasma, serum or urine
Last updated: Thursday, 25, March, 2004
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| Item | Process |
|---|---|
| Specimen | 5 mL blood in a plain or lithium heparin tube. Random urine (early morning is best) may be acceptable for a qualitative test. |
| Method | Immunoassay - qualitative or quantitative. |
| Reference Interval | <5 mIU/L (non-pregnant). The reference interval in pregnancy varies with gestational age. |
| Application | Qualitative test: diagnosis of pregnancy including ectopic pregnancy. Quantitative test: diagnosis of threatened abortion or ectopic pregnancy (sequential tests may be needed). Monitoring hCG-producing tumours (eg, hydatidiform mole, uterine choriocarcinoma, gonadal and extragonadal germ cell tumours): an assay that detects the free β subunit as well as the whole molecule is required and are also suitable for pregnancy-related applications. |
| Interpretation | If pregnancy occurs the test becomes positive 6-10 days following ovulation. The normal doubling time for the hormone in early pregnancy is 36 hours. Low levels for gestational age and/or a low rate of increase may indicate threatened abortion or ectopic pregnancy. High levels for gestational age may indicate molar pregnancy. Increased levels in a patient with a history of an hCG-producing tumour indicate residual or recurrent tumour. |
| Reference | Duffy MJ. Crit Rev Clin Lab Sci 2001; 38(3): 225-262. |