Adult patient:
Clotted blood tube
(Serum gel separator clot activator tube)
Minimum blood volume: 5 mL
Paediatric patient:
Paediatric clotted blood tube
Number of vials: 2
Minimum blood volume: 1.6 mL
Authorisation code required
No
24 Hr available service
No
Method
Immunoassay
Reference interval
| Non-pregnant (premenopause) | < 1 IU/L |
| Postmenopausal | < 7 IU/L |
| Men | < 2 IU/L |
The reference interval in pregnancy varies with gestational age
(Source: from manufacturer's kit insert)
Clinical indication
Quantitative test - diagnosis of threatened abortion or ectopic pregnancy (sequential tests may be needed).
Monitoring hCG-producing tumours (e.g. 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.
Result 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.
Measurement of uncertainty
Frequency of measurement
Daily