Late Onset (nonclassical) CAH
The androgen excess is mild enough that virilization is not apparent or goes unrecognized at birth and in early childhood. However, androgen levels are above normal and slowly rise during childhood, producing noticeable effects between 2 and 9 years of age.
Appearance of pubic hair in mid-childhood is the most common feature that leads to evaluation and diagnosis. Other accompanying features are likely to be tall stature and accelerated bone age (often 3–5 years ahead). Often present are increased muscle mass, acne, and adult body odor. In boys the penis will be enlarged. Mild clitoral enlargement may occur in girls, and sometimes a degree of prenatal virilization is recognized that may have gone unnoticed in infancy.
The principal goals of treatment of non-classical CAH are to preserve as much growth as possible and to prevent central precocious puberty if it has not already been triggered. These are more difficult challenges than in CAH detected in infancy because moderate levels of androgens will have had several years to advance bone maturation and to trigger central puberty before the disease is detected.
A diagnosis of non-classical CAH is usually confirmed by discovering extreme elevations of 17-hydroxyprogesterone along with moderately high testosterone levels. A cosyntropin stimulation test may be needed in mild cases, but usually the random levels of 17OHP are high enough to confirm the diagnosis.
The mainstay of treatment is suppression of adrenal testosterone production by a glucocorticoid such as hydrocortisone. Mineralocorticoid is only added in cases where the plasma renin activity is high.
A third key aspect of management is suppression of central precocious puberty if it has begun. The usual clues to central puberty in boys are that the testes are pubertal in size, or that testosterone remains elevated even when the 17OHP has been reduced toward normal. In girls central puberty is less often a problem, but breast development would be the main clue. Central precocious puberty is suppressed when appropriate by leuprolide.
As outlined above, recent additions to treatment to preserve growth include aromatase inhibition to slow bone maturation by reducing the amount of testosterone converted to estradiol, and use of blockers of estrogen for the same purpose.
Once adrenal suppression has been achieved, the patient needs stress steroid coverage as described above for significant illness of injury.
Other alleles result in even milder degrees of hyperandrogenism that may not even cause problems in males and may not be recognized until adolescence or later in females. Mild androgen effects in young women may include hirsutism, acne, or anovulation (which in turn can cause infertility). Testosterone levels in these women may be mildly elevated, or simply above average. These clinical features, of course, are those of polycystic ovary syndrome, and a small percentage of women with PCOS are found to have late-onset CAH when investigated.
Diagnosis of late-onset CAH may be suspected from a high 17-hydroxyprogesterone level, but some cases are so mild that the elevation is only demonstrable after cosyntropin stimulation. Treatment may involve a combination of very low dose glucocorticoid to reduce adrenal androgen production and any of various agents to block the androgen effects and/or induce ovulation.
It was characterized in 1979. Prevalence has been described as 1 in 100 in certain populations.
Read more about this topic: Congenital Adrenal Hyperplasia Due To 21-hydroxylase Deficiency
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