The 5A-THF/5B-THF ratio is a calculation used to show the preference of 5-alpha reductase activity to 5-beta reductase activity. While research is limited in the significance of 5-alpha or 5-beta reductase activity in the glucocorticoids, it can serve as an additional screening tool for overall preference for 5-alpha or 5-beta reductase activity within the androgen and progesterone pathways.

The 5a-THF/THF ratio measures the balance between two cortisol metabolites—5a-tetrahydrocortisol (5a-THF) and tetrahydrocortisol (THF). This ratio reflects the relative activity of two key enzymes involved in cortisol metabolism: 5a-reductase and 5b-reductase.

A higher ratio indicates increased 5a-reductase activity, meaning more cortisol is being converted into 5a-THF. A lower ratio reflects higher 5b-reductase activity, suggesting a different pathway of cortisol breakdown.

By evaluating this ratio, healthcare professionals can gain insight into an individual’s cortisol metabolism, adrenal function, and stress response patterns. Imbalances in this ratio may influence overall hormonal health, energy levels, and how effectively the body adapts to stress.

5β-Androstanediol is a metabolite of testosterone formed through the 5β-DHT pathway. It plays a role in assessing androgen metabolism and provides insights into 5β-reductase activity. Measuring this metabolite, along with others like 5α-Androstanediol, Androsterone, and Etiocholanolone, helps evaluate overall androgen status, especially in individuals with low DHEA or testosterone levels, where direct hormone measurements might be less informative.

Low or low-normal levels of 5β-Androstanediol may indicate insufficient androgen production, while elevated levels are commonly associated with conditions such as polycystic ovary syndrome (PCOS) or excessive androgen supplementation. Understanding these levels can guide the management of hormonal imbalances and related health conditions.

5b-Androstanediol is a testosterone metabolite that is less androgenic than 5a-DHT and 5a-Androstanediol. It is metabolized via the 5-beta metabolic pathway. In contrast, the 5-alpha metabolism makes androgens more potent (= increased 5α-reductase activity).

5b-Androstanediol is a testosterone metabolite that is less androgenic than 5a-DHT and 5a-Androstanediol. It is metabolized via the 5-beta metabolic pathway. In contrast, the 5-alpha metabolism makes androgens more potent (= increased 5α-reductase activity).

5B-AD is the result of 5-beta reduction of DHT as well as a metabolite of etiocholanolone.

The most important progesterone metabolite, pregnanediol (PDL), can serve as a urinary marker for endogenous progesterone levels and as an indicator of ovulation. PDL exists as two isomers, 5α-pregnanediol and 5β-pregnanediol. 5β-pregnanediol represents the majority end point of endogenous progesterone metabolism and appears to have little activity within the body, while 5α-pregnanediol, the lesser metabolite of PDL, can cross the blood brain barrier and may partially agonize GABA-A receptors.

5B-PD is the major progesterone metabolite.

Progesterone is produced by the corpus luteum following ovulation and to a lesser extent by the adrenal glands in both sexes. While found in the urine in small amounts, progesterone can be seen as a clinical marker of luteul activity and theraputic oral progesterone administration.

The most important progesterone metabolite, pregnanediol (PDL), can serve as a urinary marker for endogenous progesterone levels and as an indicator of ovulation. PDL exists as two isomers, 5α-pregnanediol and 5β-pregnanediol. 5β-pregnanediol represents the majority end point of endogenous progesterone metabolism and appears to have little activity within the body, while 5α-pregnanediol, the lesser metabolite of PDL, can cross the blood brain barrier and may partially agonize GABA-A receptors.

5B-THB is a terminal metabolite of corticosterone. This metabolite in combination with other terminal metabolites can be used to estimate metabolism of corticosterone. While research in elevations or low levels of single terminal metabolites is limited, assessing metabolism may provide valuable information about enzyme activity.

5B-THF is a terminal metabolite of cortisol metabolized via 5-beta reductase. This metabolite along with the other terminal metabolites can be used to determine metabolized cortisol.