What is Hydroxyprogesterone (S-17-OH-Progesterone)?
Hydroxyprogesterone, usually analyzed as 17-Hydroxyprogesterone (17-OHP), is a steroid hormone that is formed in the adrenal cortex and in smaller quantities in the ovaries and testicles. The hormone is part of the body's complex steroid metabolism and functions as an important precursor in the synthesis of both cortisol and androgens.
17-OHP is formed from progesterone by the enzyme 17α-hydroxylase and is a central intermediate in the hormonal chain that leads to the formation of cortisol. Cortisol is a vital hormone that affects the body's stress response, regulation of blood sugar and blood pressure, and the function of the immune system and inflammatory processes.
Under normal physiological conditions, 17-OHP is rapidly converted into cortisol and other steroid hormones. If this conversion is disrupted, for example due to congenital or acquired enzyme deficiency in the adrenal glands, 17-OHP can accumulate in the blood and lead to elevated levels during analysis.
Why is 17-Hydroxyprogesterone analyzed?
Analysis of 17-Hydroxyprogesterone is used to assess the hormone production of the adrenal glands and to identify disorders in cortisol synthesis. The test is a central part of the endocrinological investigation in cases of suspected congenital or acquired adrenal diseases and is used in both children and adults.
Common clinical situations in which 17-OHP is analyzed include:
- Suspected congenital adrenal hyperplasia (CAH), especially in the case of 21-hydroxylase deficiency.
- Investigation of signs of androgen excess, such as acne or increased body hair.
- unclear menstrual disorders or absence of ovulation.
- fertility investigation in both women and men.
- investigation of early puberty in children.
- follow-up and monitoring of known adrenal disease.
In newborns, analysis of 17-OHP is included in the national screening program for early detection of severe forms of CAH, which allows for rapid treatment and prevents life-threatening complications.
What can a low level of 17-Hydroxyprogesterone mean?
Low levels of 17-OHP are in most cases completely normal and reflect a well-functioning hormonal conversion in the adrenal glands. Since 17-OHP is an intermediate in steroid production, low values rarely give rise to clinical symptoms.
In certain situations, low levels can be observed in:
- reduced adrenal activity or general adrenal insufficiency
- treatment with glucocorticoids, which inhibit the body's own cortisol production
- prolonged physiological or psychological stress with an impact on the hormonal balance
Interpretation of low values always takes place in relation to other hormone analyses, such as cortisol and ACTH, as well as to the patient's symptom picture.
What can a high level of 17-Hydroxyprogesterone mean?
Elevated levels of 17-OHP indicate that the further conversion to cortisol is not working optimally. The most common cause is congenital adrenal hyperplasia, where enzyme deficiency in the adrenal glands leads to the blocking of hormone production at an early stage.
In 21-hydroxylase deficiency, which is the most common form of CAH, the enzyme defect leads to reduced cortisol production. This results in a compensatory increase in ACTH, which in turn stimulates the adrenal glands to produce larger amounts of hormone precursors, including 17-OHP.
The consequences are often:
- elevated levels of 17-Hydroxyprogesterone.
- insufficient cortisol production.
- increased formation of androgens.
Other possible causes of elevated 17-OHP levels include mild or late-onset CAH, severe physiological stress, hormonal variations during the luteal phase in menstruating women, and rarer conditions such as adrenal cortical tumors.
Symptoms of elevated 17-Hydroxyprogesterone
The symptoms of elevated 17-OHP levels vary depending on age, sex, and the degree of hormonal imbalance. In mild forms, such as non-classical CAH, symptoms may be subtle and develop gradually over time.
Common symptoms may include:
- acne and increased sebum production in the skin.
- increased body or facial hair in women.
- irregular menstruation or anovulation.
- fertility problems.
- early puberty in children.
- fatigue, low stress tolerance and impaired recovery.
When and how is the test taken?
The levels of 17-OHP are affected by both circadian rhythm and hormonal variations during the menstrual cycle. To reduce the risk of misinterpretation, the test is therefore taken under standardized conditions.
Recommended testing of Hydroxyprogesterone is usually done
- in the morning, usually before 8 a.m., when hormone production is most stable
- during the early follicular phase, usually cycle days 3–5, in menstruating women
If mild or non-classic CAH is suspected, an ACTH stimulation test can be performed to more clearly demonstrate an underlying enzyme deficiency.
Reference Range – 17-Hydroxyprogesterone
Reference ranges for 17-Hydroxyprogesterone vary between laboratories and are influenced by factors such as age, gender, time of sampling and menstrual cycle.
Women in the follicular phase usually have low levels, often in the range of approximately 0.3 to 3.0 nmol/L.
In men, the reference range is often slightly higher, approximately 0.5 to 5.0 nmol/L.
Children and newborns have their own age-specific reference ranges, which are significantly higher during the first few days of life.