ENDOCRINE DISORDERS PART 2 of 2.2 (AB) Flashcards
(97 cards)
What is the underlying cause of Cushing syndrome?
It results from abnormally high blood cortisol levels or other glucocorticoids. It may be due to exogenous steroid administration or endogenous cortisol secretion from an adrenal tumor or pituitary hypersecretion.
What is the most common cause of Cushing syndrome?
Exogenous administration of steroids over the long term is the most common cause.
How does endogenous Cushing syndrome differ in infants versus older children?
In infants it is most often due to a functioning adrenocortical tumor causing cortisol excess along with hypersecretion of other steroids. In children older than 7 years it is usually Cushing disease from an ACTH secreting pituitary adenoma leading to bilateral adrenal hyperplasia.
What are the clinical features of Cushing syndrome in infants?
A rounded face with prominent cheeks. flushed appearance known as moon facies. and generalized obesity are common in infants.
What features suggest adrenal tumor in Cushing syndrome for children?
Signs of abnormal masculinization. hirsutism of the face and trunk. pubic hair development. acne. deepening of the voice. enlargement of the clitoris in girls. impaired growth. and hypertension may be seen.
What are the signs of Cushing syndrome in older children?
They present with obesity and short stature. severe obesity of the face and trunk relative to the extremities. striae on the hips. abdomen. and thighs. delayed puberty. and may also have hypertension. hyperglycemia. and osteoporosis.
How are cortisol levels assessed in Cushing syndrome?
Cortisol levels are measured diurnally. with high levels normally at 8 AM and a decrease by midnight. In Cushing syndrome. midnight cortisol levels remain high above 4.4 µg/dL. using saliva samples.
What is the significance of the 24 hour urinary free cortisol test?
It measures increased urinary excretion of free cortisol and helps confirm Cushing syndrome.
How does the dexamethasone suppression test work in Cushing syndrome?
A single dose of dexamethasone is given at 11 PM at 25 to 30 mg/kg with a maximum of 2 mg. In normal individuals. plasma cortisol should be suppressed to less than 5 mcg/dL.
How does the CRH stimulation test differentiate causes of Cushing syndrome?
An exaggerated ACTH and cortisol response is seen in ACTH dependent causes. In adrenal tumors. there is no increase in these hormones.
What imaging studies are used in the workup of Cushing syndrome?
CT scan is used to detect adrenal tumors larger than 1.5 cm. MRI may detect ACTH secreting pituitary adenomas. and bilateral inferior petrosal sinus sampling localizes the tumor by measuring ACTH levels before and after CRH administration.
What are some differential diagnoses to consider with Cushing syndrome?
Simple obesity. generalized glucocorticoid resistance. and Cushing syndrome itself should be differentiated based on clinical and laboratory findings.
What treatments are available for Cushing syndrome?
Treatment options include transsphenoidal pituitary microsurgery. cyproheptadine a centrally acting serotonin antagonist that blocks ACTH release. and adrenalectomy in refractory cases.
What are potential complications following surgery for Cushing syndrome?
Postoperative complications may include sepsis. pancreatitis. thrombosis. poor wound healing. and sudden collapse.
What genetic mechanism causes Prader-Willi syndrome?
It is caused by uniparental disomy of chromosome 15 whereby both copies are inherited from a single parent usually the mother.
What percentage of Prader-Willi syndrome cases are due to maternal uniparental disomy?
Approximately 25 to 29 percent of cases occur due to maternal UPD.
What role do snoRNAs play in Prader-Willi syndrome?
A deficiency of paternal HB11-85 small nucleolar RNAs is associated with the syndrome.
What prenatal factor is linked with Prader-Willi syndrome?
Advanced maternal age is a risk factor. and the embryo may initially be trisomy 15 with subsequent loss of the paternal chromosome.
What are the early clinical manifestations of Prader-Willi syndrome?
Neonatal hypotonia. postnatal growth delay. almond-shaped eyes. small hands and feet. and developmental disability are early features.
How does feeding change over time in Prader-Willi syndrome?
Early in life. hypotonia leads to feeding difficulties and failure to thrive. Later. as muscle tone improves. a voracious appetite develops.
What are the major diagnostic criteria for Prader-Willi syndrome?
Major criteria include neonatal hypotonia. feeding difficulties in infancy. weight gain with hyperphagia during early childhood. characteristic dysmorphic facial features. small genitalia. and developmental delay.
What are the nutritional phases in Prader-Willi syndrome?
Phase 0 shows decreased fetal movement and lower birth weight. Phase 1a includes hypotonia with difficulty feeding. Phase 1b sees improved feeding. Phase 2a is weight gain without increased appetite. Phase 2b involves increased appetite despite satiety. Phase 3 is marked by hyperphagia. and Phase 4 shows normalization of appetite.
What management strategies are recommended for Prader-Willi syndrome?
Management includes initial treatment of hypotonia and feeding difficulties. evaluation for hypogonadism. obesity management. monitoring for scoliosis. behavioral therapy. and surgical interventions for cryptorchidism. scoliosis. or tonsillectomy if obstructive sleep apnea is present.
What is prediabetes?
Prediabetes is a state of abnormal blood glucose homeostasis that increases the risk for diabetes and cardiovascular disease. It is not a clinical entity by itself but a risk factor.
