The need for a quantitative urine hCG assay.

Area of Science:

• Clinical Chemistry
• Biochemistry
• Immunodiagnostics

Background:

• The United States lacks quantitative urine human chorionic gonadotropin (hCG) tests, despite their utility in pregnancy testing and cancer monitoring.
• Current hCG assays often fail to detect degraded hCG forms prevalent in urine.
• Investigating urinary hCG levels and the efficacy of urine testing in specific clinical scenarios is crucial.

Purpose of the Study:

• To evaluate the performance of different hCG assays in detecting degraded hCG forms in urine.
• To determine the usefulness of quantitative urine hCG testing in early pregnancy detection.
• To assess the role of quantitative urine hCG in managing false positive serum hCG results and in cancer detection.

Main Methods:

• Blind evaluation of hCG assays across 10 laboratories with diverse methodologies.
• Collection of daily urine samples from 164 women over multiple menstrual cycles or until pregnancy.
• Assay of urine samples for total hCG and analysis of 80 clinical cases with false positive serum hCG.

Main Results:

• Only the Siemens Immulite assay effectively detected degraded urine hCG forms and recognized both urine and serum hCG equally.
• Background urinary hCG levels averaged 0.04 IU/L, with a 99th centile of 1.4 IU/L in 9026 urines.
• In pregnant cycles, hCG was detectable in urine by day 24.6 (average 6.02 IU/L), establishing a sensitivity benchmark. Quantitative urine hCG aided in identifying cancer in 3 of 80 cases with false positive serum hCG.

Conclusions:

• A significant need exists for a quantitative urine hCG assay in clinical practice.
• Manufacturers are encouraged to develop and produce a quantitative urine hCG test to address current diagnostic gaps.