Beta-HCG: Difference between revisions

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==Chart ==
==Background==
[[File:HCGchart.gif|thumbnail|Levels over Time]]
*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"
{| class="wikitable"
|-
|-
| '''Week'''
| '''Gestational Week'''
| '''Minimum'''
| '''Minimum (mIU/mL)'''
| '''Maximum'''
| '''Maximum (mIU/mL)'''
|-
|-
| 3
| 3 || 5 || 50
| 0
| 5
|-
|-
| 4
| 4 || 5 || 426
| 5
| 426
|-
|-
| 5
| 5 || 18 || 7,340
| 18
| 7,340
|-
|-
| 6
| 6 || 1,080 || 56,500
| 1,080
| 56,500
|-
|-
| 7-8
| 7-8 || 7,650 || 229,000
| 7,650
| 229,000
|-
|-
| 9-12
| 9-12 || 25,700 || 288,000
| 25,700
| 288,000
|-
|-
| 13-16
| 13-16 || 13,300 || 254,000
| 13,300
| 254,000
|-
|-
| 17-24
| 17-24 || 4,060 || 165,400
| 4,060
| 165,400
|-
|-
| 25-birth
| 25-40 || 3,640 || 117,000
| 3,640
| 117,000
|-
|-
| 4-6 post
| Postpartum (4-6 wks) || NA || <5
| 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 Levels==
{{Repeat B-hCG 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==
==See Also==
*[[Pregnancy (main)]]
*[[Vaginal Bleeding Pregnant (less than 20wks)]]
*[[Vaginal Bleeding Pregnant (less than 20wks)]]
*[[Ectopic Pregnancy]]
*[[Ectopic pregnancy]]
*[[Maternal Vitals and Labs in Pregnancy]]
*[[Maternal Vitals and Labs in Pregnancy]]
*[[Miscarriage]]
*[[Molar pregnancy|Gestational trophoblastic disease]]


==References==
==References==
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[[Category:OBGYN]]
[[Category:OBGYN]]
[[Category:Labs]]

Latest revision as of 10:27, 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
  • 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[1]

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[2]
  • 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:[1][3]
    • 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[4]
Miscarriage
  • Expected to decline >21-35% in 48 hrs[5]
  • A single hCG level cannot reliably distinguish intrauterine from ectopic pregnancy[6]
  • 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[7]

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[7]
  • Very high hCG levels (>100,000 mIU/mL) should raise concern for gestational trophoblastic disease[8]
  • 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

See Also

References

  1. ↑ 1.0 1.1 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.
  2. ↑ Cole LA. New discoveries on the biology and detection of human chorionic gonadotropin. Reprod Biol Endocrinol. 2009; 7:8. PMID 19171054.
  3. ↑ 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.
  4. ↑ 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.
  5. ↑ 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.
  6. ↑ Murray H, Baakdah H, Bardell T, Tulandi T. Diagnosis and treatment of ectopic pregnancy. CMAJ. 2005; 173(8):905-912. PMID 16217116.
  7. ↑ 7.0 7.1 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.
  8. ↑ Soper JT. Gestational trophoblastic disease. Obstet Gynecol. 2006; 108(1):176-187. PMID 16816073.
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