Pregnanediol Glucuronide (PdG) is a measurable metabolite of the hormone progesterone, which prepares the body for potential pregnancy. Following ovulation, progesterone production increases significantly. Tracking PdG in urine confirms this hormonal shift has occurred. This rise in PdG confirms the corpus luteum is producing the necessary post-ovulatory hormones.
Understanding Progesterone Metabolite
Progesterone is the primary hormone produced by the corpus luteum, the structure formed from the empty follicle immediately following ovulation. This hormone circulates through the bloodstream before the liver processes it. PdG is the final, water-soluble form of progesterone, which the body then excretes in the urine.
Measuring PdG is an indirect way to assess progesterone activity. While serum progesterone is measured in nanograms per milliliter (ng/mL), its urinary counterpart, PdG, is quantified in micrograms per milliliter (\(\mu g/mL\)). PdG concentration is significantly higher in urine. This allows for daily monitoring using simple urine-based tests without the need for frequent blood draws.
Optimal PdG Levels and Measurement Timing
The goal of post-ovulation PdG testing is to confirm that the hormone level remained adequately elevated. A common threshold used to confirm ovulation is a PdG level that rises above 5 \(\mu g/mL\) for several consecutive days. This sustained elevation confirms the corpus luteum is actively producing progesterone.
Post-ovulation PdG levels vary widely between individuals, typically falling within a range of 5 \(\mu g/mL\) to 25 \(\mu g/mL\) during the luteal phase. Higher levels, such as those corresponding to a serum progesterone level above 10 \(ng/mL\), are associated with an increased chance of successful conception.
The timing of PdG measurement is important because progesterone levels peak about six to eight days after ovulation. Testing is usually recommended during the mid-luteal phase, often seven days past ovulation (7 DPO). This timing captures the hormone at its highest concentration.
Testing should take place for three to four consecutive days during the implantation window to confirm the duration and strength of the progesterone signal. The use of first-morning urine is recommended for testing. This sample is the most concentrated, giving the most accurate reflection of progesterone production.
Interpreting Sustained and Low PdG Results
A sustained PdG level is a positive indicator that the reproductive cycle is functioning effectively. When PdG remains elevated across the implantation window, it signifies that the corpus luteum produced sufficient progesterone to stabilize the endometrium. This stability is required for a fertilized egg to successfully implant.
Consistently low PdG levels suggest an issue with the quality or duration of the luteal phase. A failure to see any significant rise above the baseline follicular phase level suggests that ovulation did not occur, a condition known as anovulation. In this case, no substantial progesterone was produced.
If PdG levels rise but are not sustained, it may indicate a luteal phase defect. This occurs when the corpus luteum is insufficient or breaks down too quickly. This can result in a shortened luteal phase, which makes successful implantation difficult or contributes to early pregnancy loss.
Individuals who observe low PdG readings should consult with a healthcare provider or fertility specialist. These results offer specific data that can guide further diagnostic testing or the initiation of appropriate interventions. A medical professional is necessary to interpret the findings in the context of an individual’s overall health and fertility history.