This test measures the amount of 17-hydroxyprogesterone (17-OHP) in the blood. 17-OHP is a steroid that is used by the body to make cortisol. Cortisol is a hormone produced by the adrenal glands that helps break down protein, glucose, and lipids, maintains blood pressure, and regulates the immune system. The production of cortisol is stimulated by adrenocorticotropic hormone (ACTH), a hormone produced by the pituitary gland….This test measures the amount of 17-hydroxyprogesterone (17-OHP) in the blood. 17-OHP is a steroid that is used by the body to make cortisol. Cortisol is a hormone produced by the adrenal glands that helps break down protein, glucose, and lipids, maintains blood pressure, and regulates the immune system. The production of cortisol is stimulated by adrenocorticotropic hormone (ACTH), a hormone produced by the pituitary gland. Concentrations of cortisol normally vary throughout the day, peaking around 8 am and declining in the evening. Concentrations became elevated during illness and stress. Several enzymes are required to convert 17-OHP to cortisol. If one or more of the enzymes is deficient or dysfunctional, then inadequate amounts of cortisol are produced and cortisol precursor concentrations, such as 17-OHP, increase in the blood. The adrenal glands use up some of the excess 17-OHP by producing more androgens (male hormones). Excess androgens can cause virilisation (the development of male sexual characteristics, in both males and females). These enzyme deficiencies are inherited and the resulting excess androgens lead to a group of disorders called congenital adrenal hyperplasia (CAH). The most common cause of CAH is a lack of the enzyme 21-hydroxylase, accounting for about 90% of cases. This enzyme is the first in the chain of enzymes converting 17-OHP to cortisol. CAH is inherited as either a severe or mild type. In the more serious form of CAH, severe 21-hydroxylase deficiency, the influence of excess androgens can cause female babies to be born with atypical genitalia and it may be difficult to initially determine if they are male or female. Males with this condition will appear normal at birth but start to develop secondary sexual characteristics (signs of puberty) earlier in childhood than normal. Females at birth have atypical genitalia and later may develop hirsutism during childhood and adolescence, have irregular menstruation, and have other signs of virilisation. Babies affected by severe 21- hydroxylase deficiency CAH may also produce less aldosterone, an adrenal hormone that regulates the retention of salt. This can lead to life-threatening “salt-wasting” crises in newborns where too much fluid and salt are lost in the urine. Those affected may have low blood sodium levels (hyponatremia), high blood potassium levels (hyperkalemia), decreased aldosterone, and increased plasma renin. This severe form of 21-hydroxylase deficiency is most often detected shortly after birth or during routine newborn screening. In the more common milder form of this disorder, there may be only partial deficiency of the enzyme. This type, sometimes called late-onset or non-classical CAH, can have symptoms that begin to appear any time during childhood, adolescence, or adulthood. The symptoms can be vague, may develop slowly over time, and may vary from person to person. Though this form of CAH is not life-threatening, it may cause problems with growth, development, and puberty in children and may lead to infertility in adults. In adolescence and adulthood it is mainly females who are diagnosed. In a family with a history of CAH an adult male with infertility should be investigated for CAH. See MoreSee Less
