pituitary Flashcards
what does the anterior pituitary produce
- GH*- majority of cells
- prolactin
- ACTH
- TSH
- FSH
- LH
waht does the posterior pituitary produce
- ADH
- oxytocin
what hormone inhibits GH
- somatostatin
what is normal serum osmolality
- 285- 295
what is normal urine osmolality
- 500- 800
what is diabetes insipidus
- not enough ADH
- results in passage of large volumes of dilute urine
- urine > 3 L in 24 hours
- < 300 mosm
what are the major causes of diabetes insipidus
- central- decreased secretion of ADH
- nephrogenic- kidneys dont respond to ADH
- usu in US d/t autoimmune destruction of ADH prod cells
si/sx of DI
- polyuria, nocturia, enuria
- intense thirst with polydipsia- up to 20 L/day
- hypernatremia with severe dehydration
- hypotension, tachycardia
- dry membranes
dx of DI
- 24 hour urine collection
- hyperNa
- normal glucose
- elevated BUN
- random urine osmolality
- plasma ADH
- water deprivation test for DI vs. primary polydipsia
- desmopressin challenge
how can you dx central vs nephrogenic ADH
- central= low ADH
- nephrogenic= high ADH
treatment for DI
- mild- fluid intake
- D5W
- desmopressin for central
- HCTZ for nephrogenic
SIADH
- too much ADH
- promotes absorption of water
- decreased urinary output
- dilutional hyponatremia
- cerebral edema possible
causes of SIADH
- head trauma
- pulmonary dz
- malignancy: small cell, pancreatic
- meningitis
- drugs
- genetics
si/sx of SIADH
- sometimes asymptomatic
- HA
- anorexia
- N/V
- muscle cramps
- seizures
- AMS/ LOC
work up for SIADH
- often incidental finding on BMP
- high urine Na, urine osmols, spec gravity
- hypoNa
- elevated ADH
treatment for SIADH in asymptomatic
- fluid restriction < 1.5 L/d
- demeclocycline
treatment for SIADH in symptomatic
- 3% hypertonic solution
sheehan syndrome
- infarction/ necrosis of pituitary after severe PPH
- usu occurs gradually 10-20 years pp
- common in underdev countries
si/sx of sheehan
- lethargy, anorexia, weight loss
- failed PP lactation
- failure to resume menses weeks/mo pp
- loss of sexual hair
dx of sheehan
- MRI: early shows enlargement, late shows empty sella
- hormone eval
treatment for sheehan syndrome
- treat adrenal insufficiency first
- treat other hormonal def 4-6 weeks later
- no tx for prolactin decrease
achondroplasia
- most common cause of dwarfism
- results in asymmetric dwarfism
- short limbs, enlarged skull
- d/t genetic defect
dwarfism
- height 2 std dev below mean in kids
- 4”10’ and under
causes of proportionate dwarfism
- GH def
- GH receptor mutations
- hypothyroidism
- turner’s
- nutritional deficiencies
causes of disproportional dwarfism
- achondroplasia
- spondyloepiphyseal dysplasia
- diastrophic dysplasia
spondyloepiphyseal dysplasia
- adult ht 3-4 ft
- short trunk, barrel chest
- severe OA
- assoc with orthopaedic issues
diastrophic dysplasia
- rare, autosomal recessive cause of dwarfism
- short forearms and calves
- limited ROM
- cleft palate
- deformed hands/ feet
what causes isolated GH deficiencies?
- sellar and parasellar tumors that destroy pituitary
si/sx of GH def
- severe postnatal growth failure
- delayed one age
- hypoglycemia
- prolonged jaundice
- micropenis
- increased fat
- high pitched voice
dx of GH def
- first r/o other causes of growth failure
- if no other causes then order IGF-1, IGFBP-3, and bone age
- if IGF-1 and IGFBP-3 are low get provocative testing
- MRI to r/o structural causes
treatment for GH def
- SQ GH injections
laron syndrome
- most common cause of genetically induced GH insensitivity
- mutation in GH receptor
si/sx of laron syndrome
- severe postnatal growth factor
- small genitalia
- short limb length
- prominent forehead, depressed nasal bridge
- osteopenia
- obesity
what are pts with laron syndrome immune to
- cancer
- CVD
- DM
what is the most common cause of non-pathologic short stature
- genetics
- constitutional short stature
steps to assessing a child who appears proportional but small
- interpret growth chart
- assess child’s growth potential
- calculate height velocity
- assess bone age
- lab screenings for underlying systemic endocrine diseases
height velocity requiring referral in 2-4 years old
- < 2.2 in/year
height velocity requiring referral in 4-6 years old
- < 2 in/year
height velocity requiring referral in 6- puberty
- < 1.6 in/year in males
- <1.8 in/ year in females
how do you estimate a female childs height
- [moms ht + (dads ht -5 in)] / 2
- done at 12-15 mo
how do you estimate a male childs height
- ([moms ht + 5 in) + dads height] / 2
- done at 12-15 mo
