Pituitary II Flashcards
What hormones come from the anterior pituitary
- growth hormone
- prolactin
- adrenocorticotropic hormone
- thyroid stimulating hormone
- luteinizing hormone
- follicle stimulating hormone
What hormones come from the posterior pituitary
- antidiuretic hormone
- oxytocin
What is diabetes insipidus
deficiency in vasopressin (ADH) from the posterior pituitary
What does ADH do in the body
water preservation by the kidneys
What happen in the body when the water content in the blood is low
the brain produces more ADH–> high volume of water reabsorbed by the kidney–>low urine output–> normal water content in the blood
What happens in the body when the water content in the blood is high
brain produces less ADH–>low volume of water absorbed by the kidney–>high output of urine–>normal water content in the blood
Where is ADH created
hypothalamus
Where does ADH act in the kidney
distal renal tubules
What happens in diabetes insipidus
passage of large volumes of dilute urine (>3L/24 hrs and <300 mOsm/kg)
What are the two major causes of diabetes insipidus
- cantral: decrease secretion of ADH
- nephrogenic: the kidneys do not response to normal amounts of ADH
Two subcategories of central diabetes insipidus
- primary: no identifiable lesion on MRI or pituitary or hypothalamus
- secondary: some type of damage to hypothalamus or pituitary stalk by trauma, infection, bleed, tumor, infarction
What are the most common causes of central diabetes insipidus
- iodiopathic
- tumor on the pituitary
- cranial surgery
- head trauma
What are some causes of nephrogenic diabetes insipidus
- lithium toxicity
- hypercalcemia
- demeclocycline
- steriods
- abx
- pregnancy
- renal disease
- congenital
Signs and symtpoms of diabetes insipidus
- caused by absence of ADH*
- polyuria
- polydipsia
- nocturia
- dehydration
- hypotension
- hypernatremia
What will the serum glucose and serum electrolytes look like in diabetes insipidus
- high serum NA
- normal serum glucose
What will the plasma osmolality be in diabetes insipidus
high
What will the urine osmolality be in diabetes insipidus
low
ADH level in central diabetes insipidus
low
ADH level in nephrogenic diabetes insipidus
high
What will the water deprivation test show in central DI
increase of urine osmolality
How do you treat DI
central?
nephrogenic?
-hypotonic saline for all
central: desmopressin
nephrogenic: HCTZ
How fast do you want to decrease serum sodium in DI
0.5 mEq/hr
SIADH
excessive release of antidiuretic hormone from the posterior pituitary
What is the result of SIADH
dultional hyponatremia and low serum osmolality
What are some of the etiologies of SIADH
- head trauma
- malignancy
- meningitis
- drugs
- post pituitary surg
- neurologic disorders
- psychiatric disorders
What two malignancies most commonly cause SIADH
- small cell lung cancer
- pancreatic cancer
What are the signs and symptoms in SIADH due to
hyponatremia due to water intoxication
What are the signs and symptoms of SIADH
- headache
- N/V
- seizures
- altered mental status
- loss of consciousness
What is serum sodium in SIADH? urine sodium?
serum sodium is low
urine sodium is high
Urine osmolality is SIADH
high
Why would you do a CT of the abn or pelvis for a patient with SIADH
to check for malignancy
Treatment of a patient with asymptomatic SIADH
- restrict fluid (<1.5 L/day)
- discontinue any offending medications
- Deomeclocycline
Treatment of a symptomatic patient with SIADH
-hypertonic solution (NaCl)
What is psychogenic polydipsia
clinical disorder characterized by polyuria and polydipsia
Who does psychogenic polydipsia occur in
inpatients with psychiatric disorders
What are the two most common causes of dwarfism
- familial
- delayed constitutional growth
Definition of dwarfism
height that is 2 standard deviations below the mean for children of sex and age
height below teh 2.3rd percentile
What is the most common cause of bone dysplasia in humans
achondroplasia
What are the two main categories of dwarfism
- proportionate
- disproportionate
What causes proportionate dwarfism
- metabolic/hormonal syndromes
- GH hormone deficiency syndromes
- laron syndrome
What casues disproportionate dwarfism
- achondroplasia
- sphnydyloepiphyseal dysplasia
- diastrophic dysplasia
What mutation causes achondroplasia? autosomal dominant or recessive?
autosomal dominant
mutation in FGFR3
Features of achondroplasia
- normal torso
- short limbs
- hydrocephalus
Features of spondyloepiphyseal dysplasia
- shortened trunk
- barrel chest
- club feet
- cleft palate
- severe osteoarthritis
Features of diastrophic dysplasia
- shortened forearms and calves
- limited ROM
- cleft palate
- deformed hand/feet
- swelling of ear at birth
Signs of disproportionate dwarfism found in the eyes
- congenital cataracts
- myopia
Signs of disproportionate dwarfism found in the mouth
- bifid uvula
- high arched or cleft palate
Signs of disproportionate dwarfism found on the hands and feet
- polydactyly
- hitch hikers thumb
- clubfoot
Signs of disproportionate dwarfism in the heart
- ASD
- single atrium
- patent ductus arteriosum
- transposition of great vessels
Treatment of disproportionate dwarfism
- symptomatic relief*
- tracheotomy
- cleft palate repair
- leg braces
- back braces
- club foot surgery
What causes pituitary dwarfism
deficiency in GHRH–>GH deficiency
Signs and symptoms of pituitary dwarfism
- severe postnatal growth failure
- delayed bone age
- hypoglycemia
- prolonged jaundice
- micropenis, high pitched voice, increase body fat
What should you do first when diagnosing GHD? what comes after?
-evaluate for other causes of growth failure
-if no other evidence order
IGF-1
IGFBP-3
bone age
What is required to confirm GHD diagnosis
-provocative testing
an agent that prokes the pituitart to release a burst of GH is given–>blood draws are done
if GH,IGF-1 and IGFBP-3 remain low than GH diagnosis is confirmed
What is the most common cause cause of genetically mediated growth hormone insensitivity
Laron syndrome
What causes Laron syndrome
mutation in the GH receptor gene that does not allow GH to bind
What are the GH levels in a patient with Laron syndrome
normal or high
Clinical features of Laron syndrome
- small head circumference
- characteristic facies w/ saddle nose and prominent forehead
- delayed skeletal maturation
- abnormal body composition
- osteopenia
- obesity
What is Turner syndrome
missing X chromosome in females
What may the only presenting feature in Turner syndrome be
short stature
What are the signs of Turner syndrome
- webbed neck
- cubitus valgus
- genu valgum
- shortened 4th metacarpals
- Madelung deformity of the forearm
Treatment of pituitary dwarfism
growth hormone administered SQ
Treatment of Laron syndrome
IGF-1
What is Sheehan syndrome
infarction of the pituitary after postpartum hemorrhage
What do you look for immediately in Sheehan syndrom
adrenal insufficiency
What do you treat ACTH deficiency with
hydrocortisone of glucocorticoid
What do you treat a TSH deficiency with
levothyroxine
