CAH
Terms
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- Inheritance of CAH
- autosomal recessive
- What happens to ACTH level in CAH
- increased
- What does increased ACTH cause?
- Adrenal hyperplasia and overproduction of the adrenal steroids that do not require the deficient enzyme activity
- What classes of hormones are produced by the adrenal cortex?
- Glucocorticoids, mineralocorticoids, sex steroids
- What class of hormone is cortisol?
- Glucocorticoid
- What class of hormone is aldosterone?
- Mineralocorticoid
- What class of hormone is DHEA?
- Sex steroid
- Where is cortisol synthesized?
- zona fasciculata and zona reticularis
- Where is aldosterone synthesized?
- zona glomerulosa
- What is the most common defect leading to CAH?
- 21-hydroxylase (21-OH) deficiency
- What percentage of CAH cases are due to 21-hydroxylase (21-OH) deficiency?
- 90%
- What happens when 21-hydroxylase (21-OH) is deficient?
- 17-OHP is not converted to 11-deoxycortisol; the result is deficient cortisol, increased ACTH, adrenal hyperplasia, and increased adrenal androgen secretion.
- Which adrenal androgen is in highest excess in 21-hydroxylase (21-OH) deficiency?
- androstenedione
- How does the classic form of 21-hydroxylase (21-OH) deficiency present?
- virilization of the affected female fetus, salt-wasting crisis
- Why does salt-wasting occur?
- Aldosterone deficiency
- What is a salt wasting crisis?
- failure to gain weight, vomiting, and cardiovascular collapse. Hyponatremia and hyperkalemia may be marked, and cardiac arrest may ensue. Hypoglycemia may be present. Increased pigmentation of skin creases and genitalia due to increased ACTH may alert the clinician to the presence of adrenal insufficiency.
- How is 21-hydroxylase (21-OH) deficiency diagnosed?
- markedly elevated baseline and ACTH-stimulated levels of serum 17-OHP, adrenal androgens (particularly androstenedione), and testosterone and their suppression with glucocorticoid treatment. The plasma renin activity (PRA)/aldosterone ratio is elevated in subtle or clinical salt-wasting.
- nonclassic form of 21-OH deficiency
- presents in later childhood, at puberty, or in adult life with signs of androgen excess, including early appearance of pubic and axillary hair, tall stature, advanced bone age, acne, hirsutism, temporal hairline recession, amenorrhea, or infertility; may be symptomatic or asymptomatic
- Treatment of CAH:
- Glucocorticoids are administered to decrease ACTH secretion, suppress the hyperplastic adrenal gland, and stop the overproduction of adrenal androgens, thereby preventing progressive virilization.
- Treatment of salt-losing crisis:
- high doses of hydrocortisone (50 to 100 mg/m2 per day in three to four divided doses) are required in addition to intravenous fluids to correct the sodium and water depletion.
- How do you treat precocious puberty due to CAH?
- a luteinizing hormone-releasing hormone analog
- What levels are monitored during treatment?
- Serum levels of 17-OHP, androstenedione, testosterone, and PRA, preferably measured at 7:30 AM to 8:30 AM, prior to taking the morning medication, provide indices of control.
- What 17-OHP level should be achieved with therapy?
- Do not suppress to normal levels, but to levels at which androstenedione and testosterone are in the normal range.
- What level of PRA should be maintained?
- PRA should be maintained in the mid to high normal range.
- What treatment is required in patients who have salt-wasting and elevated PRA?
- mineralocorticoid and sodium supplementation in addition to the glucocorticoid
- What enzyme disorders can result in CAH?
- 21 hydroxylase, 11 beta-hydroxylase, 3 beta-HSD, 17-Hydroxylase Deficiency
- How does 11 beta-hydroxylase deficiency differ from 21-OH deficiency?
- Virilization more severe; Elevated levels of 11-deoxycorticosterone, a mineralocorticoid, causes volume expansion and hypertension after the first few years of life
- Can 21-OH deficiency be diagnosed prenatally?
- yes, molecular genetic testing of fetus is available and it is accurate in 95% of individuals
- If a couple are known carriers for 21-OH deficiency, what interventions can be made during pregnancy?
- The pregnant woman is treated with oral dexamethasone to prevent virilization of a female fetus.