View source for Beta-HCG

==Background==
*Human chorionic gonadotropin (hCG) is a glycoprotein hormone produced by the syncytiotrophoblast of the placenta
*Detected in maternal serum as early as 6-8 days after ovulation
*The beta subunit is specific to hCG and is what is measured by pregnancy tests (''qualitative'' = urine, ''quantitative'' = serum)
*In normal early pregnancy, serum hCG approximately doubles every 48-72 hours, peaking at 8-11 weeks of gestation<ref name="barnhart2004">Barnhart KT, Sammel MD, Rinaudo PF, et al. Symptomatic patients with an early viable intrauterine pregnancy: HCG curves redefined. Obstet Gynecol. 2004; 104(1):50-55. PMID 15229000.</ref>

==Indications==
*Confirm pregnancy
*Evaluate for [[ectopic pregnancy]] in patients with abdominal pain or [[Vaginal Bleeding Pregnant (less than 20wks)|vaginal bleeding]]
*Serial monitoring to assess viability of early pregnancy
*Evaluate for [[Molar pregnancy|gestational trophoblastic disease]] (e.g., molar pregnancy)
*Evaluate for possible miscarriage or pregnancy of unknown location

==Expected Levels by Gestational Age==
[[File:HCGchart.gif|thumbnail|B-HCG levels over time.]]
[[File:Pregnancy hormone graph.png|thumb|Estrogen, progesterone, beta-hcg levels throughout pregnancy.]]
{| class="wikitable"
|-
| '''Gestational Week'''
| '''Minimum (mIU/mL)'''
| '''Maximum (mIU/mL)'''
|-
| 3 || 5 || 50
|-
| 4 || 5 || 426
|-
| 5 || 18 || 7,340
|-
| 6 || 1,080 || 56,500
|-
| 7-8 || 7,650 || 229,000
|-
| 9-12 || 25,700 || 288,000
|-
| 13-16 || 13,300 || 254,000
|-
| 17-24 || 4,060 || 165,400
|-
| 25-40 || 3,640 || 117,000
|-
| Postpartum (4-6 wks) || NA || <5
|}
*Values represent approximate ranges and vary by laboratory and assay method<ref name="cole2009">Cole LA. New discoveries on the biology and detection of human chorionic gonadotropin. Reprod Biol Endocrinol. 2009; 7:8. PMID 19171054.</ref>
*Wide range of normal values at any given gestational age; a single value should '''not''' be used alone to determine viability

==Repeat Levels==
{{Repeat B-hCG levels}}

==Interpretation Pearls==
*hCG >1,500-3,500 mIU/mL (institutional discriminatory zone) without an intrauterine pregnancy on transvaginal ultrasound should raise suspicion for [[ectopic pregnancy]]<ref name="connolly2013">Connolly A, Ryan DH, Stuber AR, Postma HJ. Reevaluation of discriminatory and threshold levels for serum beta-hCG in early pregnancy. Obstet Gynecol. 2013; 121(1):65-70. PMID 23262929.</ref>
*Very high hCG levels (>100,000 mIU/mL) should raise concern for [[Molar pregnancy|gestational trophoblastic disease]]<ref name="soper2006">Soper JT. Gestational trophoblastic disease. Obstet Gynecol. 2006; 108(1):176-187. PMID 16816073.</ref>
*A ''plateau'' in hCG levels (rise <49% or decline <21% in 48 hrs) is suggestive of a pregnancy of unknown location and may represent ectopic or nonviable intrauterine pregnancy
*hCG levels may remain detectable for 4-6 weeks after miscarriage or completion of a pregnancy
*Heterophilic antibodies can cause false-positive results (hook effect); consider serial dilutions if clinical picture does not match hCG level

==Causes of Elevated hCG==
*Intrauterine pregnancy (most common)
*[[Ectopic pregnancy]]
*[[Molar pregnancy|Gestational trophoblastic disease (molar pregnancy)]]
*Recent pregnancy loss or termination (residual hCG)
*Exogenous hCG administration
*Germ cell tumors
*Peri-menopausal pituitary hCG production (usually low levels <14 mIU/mL)

==See Also==
*[[Pregnancy (main)]]
*[[Vaginal Bleeding Pregnant (less than 20wks)]]
*[[Ectopic pregnancy]]
*[[Maternal Vitals and Labs in Pregnancy]]
*[[Miscarriage]]
*[[Molar pregnancy|Gestational trophoblastic disease]]

==References==
<references/>

[[Category:OBGYN]]
[[Category:Labs]]