Beta-HCG: Difference between revisions

(Fix red links: point Gestational trophoblastic disease links to Molar pregnancy)
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==Background==
==Background==
*Human chorionic gonadotropin (hCG) is a glycoprotein hormone produced by the syncytiotrophoblast of the placenta
*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<ref name="wilcox1988">{{cite journal|author=Wilcox AJ, Weinberg CR, Wehmann RE, et al.|title=Measuring early pregnancy loss: laboratory and field methods|journal=Fertil Steril|year=1988|volume=49|issue=3|pages=481-485|pmid=3342901}}</ref>
*Detected in maternal serum as early as 6-8 days after ovulation<ref name="wilcox1988">Wilcox AJ, Weinberg CR, Wehmann RE, et al. Measuring early pregnancy loss: laboratory and field methods. Fertil Steril. 1988; 49(3):481-485. PMID 3342901.</ref>
*The beta subunit is specific to hCG and is what is measured by pregnancy tests (''qualitative'' = urine, ''quantitative'' = serum)
*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" />
*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==
==Indications==
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| Postpartum (4-6 wks) || NA || <5
| Postpartum (4-6 wks) || NA || <5
|}
|}
*Values represent approximate ranges and vary by laboratory and assay method<ref name="cole2009">{{cite journal|author=Cole LA|title=New discoveries on the biology and detection of human chorionic gonadotropin|journal=Reprod Biol Endocrinol|year=2009|volume=7|pages=8|pmid=19171054}}</ref>
*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
*Wide range of normal values at any given gestational age; a single value should '''not''' be used alone to determine viability


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==Interpretation Pearls==
==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">{{cite journal|author=Connolly A, Ryan DH, Stuber AR, Postma HJ|title=Reevaluation of discriminatory and threshold levels for serum beta-hCG in early pregnancy|journal=Obstet Gynecol|year=2013|volume=121|issue=1|pages=65-70|pmid=23262929}}</ref>
*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">{{cite journal|author=Soper JT|title=Gestational trophoblastic disease|journal=Obstet Gynecol|year=2006|volume=108|issue=1|pages=176-187|pmid=16816073}}</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
*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
*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<ref name="cole2006">{{cite journal|author=Cole LA|title=Phantom hCG and phantom choriocarcinoma|journal=Gynecol Oncol|year=2006|volume=100|issue=2|pages=271-280|pmid=16169064}}</ref>
*Heterophilic antibodies can cause false-positive results (hook effect); consider serial dilutions if clinical picture does not match hCG level<ref name="cole2006">Cole LA. Phantom hCG and phantom choriocarcinoma. Gynecol Oncol. 2006; 100(2):271-280. PMID 16169064.</ref>


==Causes of Elevated hCG==
==Causes of Elevated hCG==
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*Exogenous hCG administration
*Exogenous hCG administration
*Germ cell tumors
*Germ cell tumors
*Peri-menopausal pituitary hCG production (usually low levels <14 mIU/mL)<ref name="snyder2005">{{cite journal|author=Snyder JA, Haymond S, Parvin CA, et al.|title=Diagnostic considerations in the measurement of human chorionic gonadotropin in aging women|journal=Clin Chem|year=2005|volume=51|issue=10|pages=1830-1835|pmid=16099937}}</ref>
*Peri-menopausal pituitary hCG production (usually low levels <14 mIU/mL)<ref name="snyder2005">Snyder JA, Haymond S, Parvin CA, et al. Diagnostic considerations in the measurement of human chorionic gonadotropin in aging women. Clin Chem. 2005; 51(10):1830-1835. PMID 16099937.</ref>


==See Also==
==See Also==

Revision as of 06:33, 22 March 2026

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[1]
  • 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[2]

Indications

Expected Levels by Gestational Age

B-HCG levels over time.
Estrogen, progesterone, beta-hcg levels throughout pregnancy.
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[3]
  • 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

Pregnancy Type B-hCG Change
Normal
  • Minimum expected rise depends on initial hCG value:[2][4]
    • Initial hCG <1,500 mIU/mL: minimum 49% rise in 48hrs
    • Initial hCG 1,500-3,000 mIU/mL: minimum 40% rise in 48hrs
    • Initial hCG >3,000 mIU/mL: minimum 33% rise in 48hrs
  • hCG typically doubles approximately every 48-72 hours in early pregnancy
  • Rate of rise slows after hCG reaches approximately 6,000-10,000 mIU/mL
Ectopic
  • Increases or decreases more slowly than expected ("plateau")
  • Approximately 21% of ectopic pregnancies have a normal hCG rise[5]
Miscarriage
  • Expected to decline >21-35% in 48 hrs[6]
  • A single hCG level cannot reliably distinguish intrauterine from ectopic pregnancy[7]
  • The discriminatory zone (typically 1,500-3,500 mIU/mL depending on institution) is the hCG level above which a gestational sac should be visible on transvaginal ultrasound[8]

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[8]
  • Very high hCG levels (>100,000 mIU/mL) should raise concern for gestational trophoblastic disease[9]
  • 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[10]

Causes of Elevated hCG

See Also

References

  1. ↑ Wilcox AJ, Weinberg CR, Wehmann RE, et al. Measuring early pregnancy loss: laboratory and field methods. Fertil Steril. 1988; 49(3):481-485. PMID 3342901.
  2. ↑ 2.0 2.1 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.
  3. ↑ Cole LA. New discoveries on the biology and detection of human chorionic gonadotropin. Reprod Biol Endocrinol. 2009; 7:8. PMID 19171054.
  4. ↑ Barnhart KT, Guo W, Cary MS, et al. Differences in serum human chorionic gonadotropin rise in early pregnancy by race and value at presentation. Obstet Gynecol. 2016; 128(3):504-511. PMID 27500347.
  5. ↑ Silva C, Sammel MD, Zhou L, et al. Human chorionic gonadotropin profile for women with ectopic pregnancy. Obstet Gynecol. 2006; 107(3):605-610. PMID 16507930.
  6. ↑ Doubilet PM, Benson CB, Bourne T, Blaivas M. Diagnostic criteria for nonviable pregnancy early in the first trimester. N Engl J Med. 2013; 369(15):1443-1451. PMID 24106937.
  7. ↑ Murray H, Baakdah H, Bardell T, Tulandi T. Diagnosis and treatment of ectopic pregnancy. CMAJ. 2005; 173(8):905-912. PMID 16217116.
  8. ↑ 8.0 8.1 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.
  9. ↑ Soper JT. Gestational trophoblastic disease. Obstet Gynecol. 2006; 108(1):176-187. PMID 16816073.
  10. ↑ Cole LA. Phantom hCG and phantom choriocarcinoma. Gynecol Oncol. 2006; 100(2):271-280. PMID 16169064.
  11. ↑ Snyder JA, Haymond S, Parvin CA, et al. Diagnostic considerations in the measurement of human chorionic gonadotropin in aging women. Clin Chem. 2005; 51(10):1830-1835. PMID 16099937.
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