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Congenital Adrenal Hyperplasia
| Question | Answer |
|---|---|
| this is a familial disorder of adrenal steroid biosynthesis with autosomal recessive mode of inheritance. the deficit is expressed as adrenal enzyme deficiency. | congenital adrenal hyperplasia (CAH) |
| what are the four major enzyme deficiencies that are clinically important? | 21 hydroxylase, 11beta hydroxylase, 17alpha hydroxylase, 3beta HSD |
| the phenotype of CAH depends on what? | the degree or type of gene deletion or mutation and the resultant deficiency of the steroidogenic enzyme. |
| Is the sex of hte neonate with CAH clear? | no, it's unclear because of genital ambiguity |
| what happens in CAH with the enzyme deficiency? | the enzyme deficient causes reduction in end products, accumulation of hormone precursors and increased ACTH production. |
| what is the primary endogenous mineralocorticoid? | aldosterone |
| what are some hormones besides aldosterone that have mineralocorticoid function? | progesterone, deoxycorticosterone |
| what is the function o faldosterone? | acts on kidneys to provide active reabsorption o fsodium and associated passive reabsorption of water, as well as active secretion of potassium |
| this is the most common type of hormone deficiency in CAH, and accounts for over eighty percent of cases of CAH. | 21 hydroxylase deficiency. |
| where is the gene for 21 hydorxylase located? | short arm of chromosome 6 near the C4 locus in close, and is in close association with HLA genes. |
| how can you detect a heterozygous carrier of 21 hydroxylase deficiency? | ACTH stimulation test |
| what are some characteristics of 21 hydroxylase deficiency? | reduced productoin of cortisol and aldosterone and increased production of progesterone, 17 OH progesterone, and sex steroids. The urinary steroid metabolites are elevated above normal levels. |
| in 21 hydroxylase deficiency, decreased secretion of aldosterone results in what? | salt loss with hyponatremia, hyperkalemia, increased plasma renin activity. |
| in a partial enzyme deficiency of 21 hydroxylase, is the enzyme deficiency expressed? | no. patient remains normonatremic and normokalemic |
| what do the excess androgens in 21 hydroxylase deficiency cause in girls and boys? | virilization of girls and ambiguous genitalia and dark scrotum in boys |
| what are the two forms of 21 hydroxylase deficiency? | 1. classic early virilization type with or without salt losing crisis. 2. non-classic type with late-onset virilization |
| in 21 hydroxylase deficiency, male babies iwth non salt losing non-classic type become symptomatic when? | late childhood when they may show signs of sexual precocity |
| what explains the fact that members of the same family can have 21 hydroxylase deficiency of classic and non-classic & asymptomatic forms? | allelic variations of the same enzyme |
| mass neonatal screening for 21 hydroxylase deficiency screens for what? | 17 OH progesterone |
| this enzyme deficiency accounts for about five to ten percent of cases of CAH. gene is located on the long arm of chromosome 8. | 11 beta HSD deficiency |
| described characteristics of 11BHSD deficiency | low plasma renin activity and elevation of serum 11 deoxycorticortisol and 11 deoxycorticosterone. There is salt retention, hypertension, and hhypokalemic alkalosis. Elevated plasma androgens may cause virilization of female fetus |
| what causes the salt retention in 11BHSD deficiency? | the strong activity o fdeoxycorticosterone |
| genetic defect of this enzyme is located on chromosome 10 | 17 alpha hydroxylase deficiency |
| describe some characteristics of 17 alpha hydroxylase deficiency | similar features of those of 11 hydroxylase deficiency except that androgens are low, so no virilization in girls and genitalia is ambiguous in boys. |
| this is a very rare disorder that results in accumulation of DHEA, which is converted to testosterone in peripheral tissues. | 3BHSD |
| 3BHSD deficiency can cause what? | virilization of female fetus and leads to ambiguous genitalia in the newborn. |
| this part of the adrenal gland primarily produces mineralocorticoids. | zona glomerulosa |
| this part of the adrenal gland makes primarily glucocorticoids | zona fasciculata |
| this part of the adrenal gland makes primarily androgens | zona reticularis |
| what symptoms appear with CAH? | increased linear growth and advanced bone age nad eventual short stature. pseudohermaphroditism in girls due to androgen virilizing aeffect. isosexual precocity in boys with small infantile testes. |
| what are the symptoms you would see especially in 21 hydroxylase deficiency? | adrenal crisis with salt loss and metabolic acidosis or hypertension and hypokalemic alkalosis. low cortisol with high androgens, ACTH and steroid precursors ex: 17 OH progesterone or 11 deoxycortisol. |
| with 21 hydroxylase deficiency, what is diagnosis confirmed by? | measurement of ACTH, cortisol, aldosterone, 17OH progesterone, testosterone, and urinary 17 ketosteroids. |
| you should be alert for 21 hydroxylase deficiency in all babies presenting with these symptoms... | diarrhea, vomiting, hypoglycemia, increased blood pressure |
| the clinical course of the phenotype depends upon thes two things | the nature and the severity of the enzyme deficiency |
| approximately fifty percent of patients with classic CAH due to 21 hydroxylase deficiency have this characteristic... | salt wasting due to inadequate aldosterone synthesis. girls are usually recognized at birth due to ambiguous genitalia. |
| non salt losing CAH presents when and how? | late in childhood with precocious pubic hair and/or cliteromegaly, often accompanied by accelerated growth and advanced bone age. |
| in non salt losing CAH, those with mild deficiencies of the enzyme present when and how? | in adolescence or adulthood with varying virilizing symptoms ranging from oligomenorrhea to hirstuism and infertility |
| how do girls with severe CAH present? | have ambiguous genitalia at birth: complete fusion of the labiosrotal folds and a phallic urethra. cliteromegaly and partial fusion of the labioscrotal folds. |
| how do girls present with less severe forms of CAH? | genitalia is normal at birth, precocious pubic hair and cliteromegaly and excess facial or body hair appear later in childhood, often accompanied by tall stature |
| how do boys with CAH present? | unrecognized at birth because genitalia are normal. they are not dxed til later, often with a salt wasting crisis resulting in dehydration, hypotension, hyponatremia, and hyperkalemia or late rin childhood with early pubic hair and phallic enlargement |
| how do boys with CAH present in terms of body growth? | lateral linear growth and advancemen of skeletal maturation. |
| how do boys with CAH present in terms of blood pressure? | high blood pressure and hypokalemia may occur in those with 11 bet ahydroxylase deficiency and 17 alpha hydroxylase deficiency due to the accumulation of the mineralocorticoid desoxycorticosterone |
| what are some laboratory findings diagnostic of CAH? | inadequate production of cortisol and/or aldosterone in the presence of accumulatin of excess concentrations of precursor hormone |
| what lab findings are diagnostic in 21 hydroxylase deficiency? | very high serum 17 hydroxyprogesterone is characteristic together with very high urinary pregnanetriol (metabolite of 17 hydroxyprogesterone) |
| what lab findings are diagnostic of 11 beta hydroxylase deficiency? | high serum 11 deoxycorticosterone and 11 deoxycortisol concentrations with elevation of its urinary metabolites (tetrahydrocompound-S). Both accompanied by elevated 24 hour urinary 17 ketosteroids, the urinary metabolites of adrenal androgens |
| what are lab diagnostics of salt wasting forms of adrenal hyperplasia? | low serum aldosterone, hyponatremia, hyperkalemia, and elevated plasma renin activity indicating hypovolemia. |
| what are laboratory findings of hypertensive forms of CAH? (11beta hydrolxylase deficiency and 17alpha hydroxylase deficiency) | they are associated with suppressed plasma renin activity and hypokalemia |
| what laboratory test is essential in the evaluation of the infant with ambiguous genitalia in order to establish the chromosomal sex? | karyotype |
| prenatal diagnosis of adrenal hyperplasia is possible via... | biochemical and genetic tests |
| this imaging is done in an infant with ambiguous genitalia to demonstrate the presence or absence of a uterus or associated renal anomalies. | pelvic ultrasound |
| this imaging study is often helpful to define the anatomy of the internal genitalia. | urogenitogram |
| this imaging study is done of the adrenal gland to rule out bilateral adrenal hemorrhage in the patient with signs of acute adrenal failure | CT scan |
| this imaging stuyd is useful in teh evaluation o fthe child who develops precocious pubic hair, cliteromegaly,or accelerated linear growth. | bone age |
| describe the treatment of children with CAH | treatment is lifelong. |
| describe some treatment goals in CAH | maintain growth velocity and skeletal maturation, normalize electrolytes and hormone levels using the smallest does of glucocorticoids that will suppress the increased ACTH to normal. mineralocorticoid replacement may be needed to sustain normal electrol |
| list some treatment options for CAH | steroid replacement, supportive therapy when needed, treatment is life long. plastic surgery for ambiguous genitalia at early age, genetic counseling, psychological support |
| what is the long term glucocorticoid used? | hydrocortisone-divided into three oral doses. |
| the dose of hydrocortisone is doubled during when? | crisis and stressful conditions. |
| what are the goals of therapy with glucocorticoids during crisis and stressful conditions | replace the body's requirement under normal condiitons and during stress. suppress ACTH secretion, which drives the adrenal gland to overproduce adrenal androgens in virilizing forms of congenital adrenal hyperplasia |
| what is the mineralocorticoid given during supplementation? | given once daily orally, and is indicated for patients who have salt wasting forms of CAH to replace the aldosterone that is insufficiently produced by the adrenal cortex. it will restore the sodium potassium balance. |
| how is neonatal screening done? | by measuring 17 hydroxyprogesterone from heel blood samples collected on filter paper. mass neonatal screening is done in US. This approach has permitted early identification of newborns with CAH and prevented salt wasting crisis in boys unrecogni @birth |
| this approach also identified... | the completely virilized girls with ambiguous genitalia who may be mistaken for boys with cryptorchidism. |
| how is prenatal diagnosis done? | chorionic villus sampling at 8-12 weeks and amniocentesis at 18-20 weeks. |
| how is antenatal diagnosis done? | HLA typing in combination with measurement of 17 OH progesterone and androstenedione in amniotic fluid is used for antenatal diagnosis. |
| describe the prognosis | is good and complications like short stature, sexual precocity and metabolic effects are not seen with early adequate therapy. |
| even with adequate therapy early on, children with CAH are at increased risk of developing these | mesodermal tumors ex: osteogenic sarcoma, pulmonary liposarcoma, uterine leiomyomata and brain tumors |
Created by:
aferdo01
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