human chorionic gonadotropin
DESCRIPTION
Human Chorionic Gonadotropin. Photo of average 14 y.o. patient at the Children’s ED. 6 Questions. How Early is it detectable? Causes of false +ve urine HCG? Causes of false -ve urine HCG? U/S findings at different hCG levels? Does dilution really matter? Is doubling time accurate?. - PowerPoint PPT PresentationTRANSCRIPT
Human Chorionic Gonadotropin
Photo of average
14 y.o. patient at
the Children’s
ED
6 Questions
How Early is it detectable?
Causes of false +ve urine HCG?
Causes of false -ve urine HCG?
U/S findings at different hCG levels?
Does dilution really matter?
Is doubling time accurate?
How long does it take to get back?
Urine: 3 minutes
Serum: 1 hour
Ascheim-Zondek test: 100 hours
What is HCG?
• Glycoprotein
• First measurable placental product
• Supports the corpus luteum
-
Alpha Subunit
Beta Subunit
How does the test work?
Tracer Antibody
Capture Antibody
Tracer Antibody
Capture Antibody
Alpha Subunit
Beta Subunit
Antibody Sandwhich
How early will it be positive?
Depends…
HCG Trends
Day HCG (mIU/ml)
1 0.65
2 2.21
3 5.2
4 11.83
5 25.22
6 51.87
7 87.88
Detection Level:
Urine: Above 25
Ddx (+) hCG
• Physiologic artifact
• Exogenous hCG
• Gestational Trophoblastic Disease
• HAAA
• Non-gestational malignancy
False Negative Ddx
• Early Pregnancy • Hook Effect• Expired test• Sensory deficit• Inadequate test time
What should I see and when should I see it
Is Dilution really a problem?
• Standard of 1.010 - 1.015
• QuickVue: “1.007”
• Need more data to be 100% sure
Is doubling-time accurate?
“Doubling Time”
66%53%
Summary
• Ab Sandwhich
• As early as 28 days post LMP
• Remember false + and false -
• Minimum 53% rise in 2 days