hCG (serum, quantitative)

Outside pregnancy the expected value is below about 5 IU/L (a little higher, up to about 10, after the menopause); in pregnancy it climbs week by week, roughly doubling every two to three days early on, and each lab prints its own week-specific ranges, so the printed range is the one to use.

hCG is the hormone made by the placenta from the earliest days of pregnancy, and it is the hormone that home pregnancy tests detect in urine. The blood test measures the exact amount. Outside pregnancy it is almost undetectable, but a few tumours make it, so it is also used as a tumour marker.

It is requested to confirm early pregnancy and to follow how it is progressing, particularly in early pregnancy units where the change over 48 hours is watched. It is also used before some scans and treatments, and as a marker for certain testicular, ovarian and placental tumours.

• Pregnancy, rising steadily through the first ten weeks
• Twin or multiple pregnancy
• Recent miscarriage or termination, until it clears over a few weeks
• Molar pregnancy and related placental conditions
• Some testicular, ovarian and other tumours
• The menopause, slightly, because the pituitary makes a small amount
• Fertility treatment that includes an hCG injection

• Time after a pregnancy has ended, as it clears over days to weeks
• Later pregnancy, where it falls from its peak at around ten weeks and then plateaus
• Not being pregnant, where the expected value is below the cut-off

• An hCG trigger injection used in fertility treatment can be detected for around ten days
• After the menopause the pituitary makes small amounts, giving low positive values
• Rare interfering antibodies give a false positive on some assays, which a urine test can help sort out

No fasting needed. In early pregnancy the change between two samples 48 hours apart is more informative than a single number. Dates and any recent pregnancy, miscarriage or fertility injection are relevant to reading it.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.