Endocrinology Pt. 1 Flashcards
Short stature is defined as height that is ____ standard deviations below the mean
two
What is normal variant short stature?
What is pathologic short stature?
- What is normal variant short stature?
- Describes a child whose height is below the third percentile but is growing with a normal growth velocity
- What is pathologic short stature?
- Describes a child whose height is below the third percentile but is growing with a suboptimal growth velocity
Most children, when they have completed their growth, are within ___ SDs, or __ inches of their MPH
+/-2SDs or 4 inches
What drugs can lead to short stature?
Steroids, or stimulants for ADHD that result in significant appetite suppression and poor weight gain
Why is social history critical in evaluation of short stature?
Because children who live in neglected or hostile environments may exhibit short stature because of psychosocial deprivation
What are the two most common categories of normal variant short stature?
Familal short stature and constitutional delay with delayed puberty
What is familial short stature?
Height at least 2 SDs below the mean with a short MPH but with a normal bone age, a normal onset of puberty, and a minimum growth of 2 inches per year
What is consitutional short stature?
Height at least 2 SDs below the mean with a history of delayed puberty in either or both parents, a delayed bone age, and late onset puberty
What are causes of prenatal onset proportionate short stature?
- Environmental exposures (in utero exposure to tobacco and alcohol)
- Chromosome disorders (Down syndrome, Turner)
- Genetic syndromes
- Viral infection early in pregnancy
What labs should be done in the evaluation of pathologic short stature?
CBC, ESR, T4, serum electrolytes, creatinine, bicarb, IGF-1
What radiographic studies are done in the evaluation of patients with pathologic short stature?
- Bone age: determination is very helpful to compare with chronologic age
- AP and lateral skull radiographs are necessary to assess the pituitary gland
If a person with short stature has bone age = chronologic age, what is the differential?
- Familal short stature
- Intrauterine growth retardation
- Turner syndrome
- Skeletal dysplasia
What endocrinopathies cause short stature?
- Growth hormone deficiency
- Hypothyroidism
- Hypercortisolism
- Turner syndrome
Patients with GH deficiency have ______ bone age and must have an ____ to rule out a CNS lesion
delayed; MRI
What lab findings are associated with hypothyroidism?
- Increased TSH
- Low T4
- Positive antithyroid peroxidase antibodies
Puberty begins when there is a reduction in ______ _______ resulting in activation of the _______
Hypothalamic inhibition; HPGA (hypothalamic-pituitary-gonadal axis)
Onset of female puberty is between __ and __ years of age
7 and 13
________ is the onset of breast development
Thelarche
What is the first sign of puberty in girls?
Breast buds (adrenarche in 15% of girls)
What are the roles of FSH and LH in menstruation?
FSH stimulates the ovaries to produce ovarian follicles, which in turn produce estrogen
LH is responsible for the positive feedback in the middle of the menstrual cycle resulting in the release of egg
Male puberty onset is between __ and __ years of age
9 and 14
What is the first sign of male puberty?
Testicular enlargement
What are the roles of FSH and LH in male puberty?
FSH: Stimulates the seminiferous tubules in the testes to produce sperm
LH: stimulates the testicular Leydig cells to produce androgens, which in turn are responsible for penile enlargement and the growth of axillary, facial, and pubic hair
What is precocious puberty in girls vs boys?
Girls: Presence of breast development or pubic hair before 7 years of age or menarche before 9 years of age
Boys: Any pubertal changes before 9 years of age
When is treatment indicated for premature thelarche?
If there is also pubic hair development or a rapid growth spurt
Premature adrenarche is more common in ___ than ____
girls > boys
When does premature adrenarche clasically present? What is the treatment?
After 5 years of age, with the onset of pubic hair growth, axillary growth and apocrine odor
No treatment is indicated
Delayed puberty in boys means no testicular enlargement by ____ years of age
14
Delayed puberty in girls means no breast tissue by ____ years of age or no menarche by ___ years of age
13;14
What is the difference between Hypogonadotropic hypogonadism and Hypergonadotropic hypogonadism?
- Hypogonadotropic hypogonadism: Inactivity of the hypothalamus and pituitary gland; patients have low FSH, low LH, and in turn, low testosterone and low estradiol
- Hypergonadotropic hypogonadism: End organ function (gonadal failure) leading to high FSH and high LH levels with low testosterone or low estradiol levels
What chromosomal disorders can cause hypergonadotropic hypogonadism?
In boys: Klinefelter syndrome (XXY)
In girls: Turner syndrome (XO) or gonadal dysgenesis
How is delayed puberty evaluated?
CBC, ESR, T4, testosterone or estradiol, FSH, LH, prolactin level, and bone age are necessary
What is produced by the adrenal cortex?
- Mineralcorticoids (aldosterone)
- Glucocorticoids (cortisol)
- Androgens (DHEA)
What causes primary adrenal insufficiency? How do patients present?
Causes: destruction of the adrenal cortex or enzyme deficiency
Presentation: Signs and symptoms of cortisol deficiency (anorexia, weakness, hyponatremia, hypotension, and increased pigmentation over healed scars), and aldosterone deficiency (failure to thrive, salt craving, hyponatremia, and hyperkalemia)
What causes secondary adrenal insufficiency?
Any process that interferes with the release of cortisol-releasing hormone from the hypothalamus or ACTH from the pituitary
In contrast to primary adrenal insufficiency, serum _______ may be normal in secondary adrenal insufficiency because there is no ________ deficiency
potassium; aldosterone
What is Addison’s disease?
Adrenal insufficiency resulting from autoimmune destruction of the adrenal cortex by lymphocytic infiltration
How is acquired adrenal insufficiency evaluated?
ACTH stimulation test is the test of choice and measures adrenal cortisol reserve by comparing the baseline cortisol level with the cortisol level 1 hour after ACTH injection (would see blunted response; normally the cortisol level doubles)
What is the management of acquired adrenal insufficiency (Adrenal crisis)?
- Prompt treatment requires IV fluids with 5% dextrose in normal saline (to correct hypotension and hyponatremia, and to prevent hypoglycemia)
- Parenteral steroids are given until the patient is stablized
What are the clinical features of glucocorticoid excess?
Poor growth with delayed bone age, central obesity, moon facies, nuchal fat pad, easy bruisability, purplish striae, htn, and glucose intolerance
What are the three major causes of hypercortisolism?
- Iatrogenic (the most common cause)
- Cushing Syndrome (excessive glucocorticoid production by benign or malignant adrenal tumors)
- Cushing disease (Excessive ACTH production by a pituitary tumor such as a microadenoma)
How is glucocorticoid excess diagnosed?
- Elevated free cortisol in 24 hour urine collection
- Absence of expected cortisol suppression seen in an overnight dexamethasone suppression test
