Progesterone is conjugated in human urine

Area of Science:

• Endocrinology
• Steroid Biochemistry

Background:

• Progesterone is a key steroid hormone crucial for pregnancy.
• Urinary excretion of steroid metabolites provides insights into hormonal metabolism.
• The conjugated forms of progesterone in urine have not been fully characterized.

Purpose of the Study:

• To identify and characterize previously unknown progesterone conjugates in human urine.
• To investigate the physiological conjugation of progesterone during pregnancy.

Main Methods:

• Urine from near-term pregnant women was analyzed using anion exchange chromatography.
• Fractions were subjected to various hydrolysis treatments (immediate, thermal, enzymatic, acid).
• Progesterone levels were quantified using radioimmunoassay after thin layer chromatography purification.

Main Results:

• Two novel, negatively charged progesterone conjugates were identified in human urine.
• These conjugates eluted similarly to known testosterone conjugates (glucuronide and sulfate) on anion exchange columns.
• The levels of these newly discovered conjugates were found to be equal to or greater than free (unconjugated) urinary progesterone.

Conclusions:

• Progesterone exists in at least two distinct conjugated forms in human urine.
• These findings indicate a previously undescribed physiological conjugation of progesterone.
• Further research is needed to elucidate the exact chemical structures of these conjugates.