congenital adrenal hyperplasia
Friday 15 April 2005
Definition: Congenital adrenal hyperplasia (CAH) represents a group of autosomal-recessive, inherited metabolic errors, each characterized by a deficiency or total lack of a particular enzyme involved in the biosynthesis of cortical steroids, particularly cortisol.
Congenital adrenal hyperplasia, unlike all other conditions responsible for the appearance of ambiguous genitalia in the newborn, may be life threatening because of a lack of synthesis of specific adrenal steroids.
Prompt diagnosis and appropriate therapy are essential. With early treatment, normal external genitalia and fertility can be achieved. The manifestations of the adrenogenital syndrome in the XX individual are most easily understood by examining the simplifi ed biosynthetic pathways of mineralocorticoid, glucocorticoid, and sex steroids.
Two enzymes, 21-hydroxylase and 11β-hydroxylase, participate in the formation of the glucocorticoids, desoxycorticosterone and cortisol, and the mineralocorticoid, aldosterone, but neither in testosterone nor the estrogens, estrone or estradiol.
Deficiency of either enzyme in the 46,XX female leads to elevated adrenocorticotropic hormone (ACTH) products and hence elevated levels of testosterone and other strongly androgenic intermediates, which may result in sexual ambiguity or marked virilization of the newborn’s external genitalia.
Steroidogenesis is then channeled into other pathways, leading to increased production of androgens, which accounts for virilization. Simultaneously, the deficiency of cortisol results in increased secretion of ACTH, resulting in adrenal hyperplasia. Certain enzyme defects may also impair aldosterone secretion, adding salt wasting to the virilizing syndrome.
Other enzyme deficiencies may be incompatible with life or, in rare instances, may involve only the aldosterone pathway without involving cortisol synthesis.
No gender preference, usually presents in children, rarely in adults
Symptoms depend on specific defect; include salt wasting, virilization, adrenogenital syndrome, hypertension.
The congenital adrenal hyperplasia (CAH) is the most common cause of ambiguous genitalia. It manifests as various degrees of virilization in girls and as precocious puberty in boys. Most cases are secondary to 21-hydroxylase deficiency. An elevated 17-hydroxy-progesterone level indicates the diagnosis of CAH.
Adrenal glands with a limb over 20 mm long and 4 mm wide and with normal corticomedullary differentiation are suggestive of CAH.
Some authors believe that it is not just the size of the gland but a combination of its size, echogenicity, and surface contour that helps make the diagnosis of CAH.
Al-Alwan et al found that a combination of a limb width greater than 4 mm, a lobulated surface, and stippled echogenicity had a sensitivity of 92% and a specificity of 100% in making the diagnosis.
The presence of normal-sized adrenal glands does not exclude the diagnosis of CAH, and a cerebriform appearance of the adrenal glands is reportedly specific for CAH.
A normal uterus and ovaries are seen at US in female pseudohermaphroditism. Some boys with CAH may present with intratesticular nodularity (hyperplasia of Leydig cells).
Congenital adrenal hyperplasia (CAH) results from a deficiency in one or another of the enzymes of cortisol biosynthesis.
Because of defective cortisol synthesis, ACTH levels increase, resulting in overproduction and accumulation of cortisol precursors, particularly 17-OHP, proximal to the block. This causes excessive production of androgens, resulting in virilization.
Various autosomal recessive syndromes due to enzyme deficiencies in biosynthesis of adrenal steroids, diverting production to other pathways and causing elevated ACTH levels and adrenocortical hyperplasia
There is a spectrum of these syndromes, and with each one, there may be a total lack of a particular enzyme or a mutation that only mildly impairs the effectiveness of the enzyme.
salt wasting syndrome
simple virilizing syndrome
nonclassic virilizing syndrome
congenital adrenal hyperplasia tumors
ovarian tumor of the adrenogenital syndrome (11684964)
- 21-hydroxylase deficiency
- ovarian or paraovarian soft brown masses
- identical to the testicular tumor of the adrenogenital syndrome
Leydig cell tumor
- testicular Leydig cell tumor
- ovarian Leydig cell tumor
- bilateral ovarian Leydig cell tumors
marked adrenal enlargement (15g each gland) with cerebriform appearance, - tan-brown
secondary to elevated ACTH (due to reduced cortisol secretion)
diffuse cortical hyperplasia, particularly of zona reticularis-like compact cells
bilateral adrenal hyperplasia due to ectopic ACTH
- not grossly cerebriform
- may have metastatic carcinoma
- differentiate clinically
exogenous glucocorticoids and mineralocorticoids to provide cortisol and suppress ACTH levels
surgical correction of external genitalia