Anterior pituitary Flashcards
How do you diagnosis hyperprolactinemia?
A single measurement of increased serum prolactin
What are some differentials if the serum prolactin is >250 ng/ml?
- Prolactinoma - prolactin secreting pituitary tumor
- Some drugs - metoclopramide and risperidone (dopamine antagonists), may increase prolactin > 200 ng/ml
- Microprolactinomas can also have prolactin levels in the 100-250 ng/ml range
What can cause mild to moderate hyperprolactinemia (25-100 ng/ml)??
Infundibular stalk compression - a larger pituitary mass
Non-prolactin secreting tumor with infundibular stalk compression and inhibition of dopamine transport to the lactotroph
Physiological causes of hyperprolactinemia
Pregnancy Lactation Exercise Sleep Stress
What are some medications that may cause hyperprolactinemia?
Antihypertensives (methyldopa)
Estrogens
D2 dopamine receptor antagonists (metoclopromide, domperidone)
Neuroleptics/antipsychotics (phenothiazines, butyrophenones, risperidone - block dopamine receptors)
Pathological causes of hyperprolactinemia
Hypothalamic-pituitary stalk damage – infiltrative disorders (Sarcoidosis), irradiation to the brain, trauma, tumors
Pituitary-prolactinomas, macroadenoma (with compression of infundibular stalk), lymphocytic hypophysitis (autoimmune)
How does hyperprolactinemia present in young women?
Menstrual irregularities, galactorrhea (50-80%) and infertility
How does hyperprolactinemia present in men?
Decrease in libido and erectile dysfunction as a result of hypogonadism, galactorrhea is less common (20-30%)
How do patients with hyperprolactinemia get hypogonadism?
Hyperprolactinemia inhibits the pituitary gonadotropins, FSH and LH
How might macroprolactinomas present?
Headaches
Neurologic deficits d/t cavernous sinus involvement and vision changes d/t optic chiasm compression and cavernous sinus involvement
Treatment for hyperprolactinemia
Dopamine agonists
Cabergoline
Bromocriptine
How do domaine agonists treat hyperprolactinemia?
Suppress prolactin production via activation of D2 receptors
How does cabergoline treat hyperprolactinemia?
Dopamine agonist
SE of Cavergoline
Nausea Vomiting Orthostatic lightheadedness Dizziness Nasal congestion Cardiac valvulopathy in Parkinson's patients
When is bromocriptine used to treat hyperprolactinemia?
When patients are undergoing fertility induction that also have hyperprolactinemia
It’s also the initial treatment for macroprolactinomas that have caused compromise of vision, neurologic deficits and pituitary function
What are some clinical features of acromegaly?
Headache Enlargement of lips, nose and tongue Cardiomyopathy Hypertension Enlargement of liver Enlargement of hands Arthropathy Carpal tunnel syndrome Skull growth Prognathism Increased sweating Thickened skin
How is acromegaly diagnosed?
Measurement of serum IGF-1
Oral glucose test
How does the oral glucose test diagnose Acromegaly?
Give 100 gram glucose load
Normally glucose suppresses GH level to less than 1 ng/ml by 2 hours
GH levels may paradoxically increase, remain unchanged or decrease but not <1 ng/ml
Treatment for acromegaly
Transsphenoidal surgery Radiation therapy Drug therapy -- somatostatin receptor ligands (SRLs) = octreotide and lanreotide Cabergoline = dopamine agonist Pegvisomant = GH receptor antagonist
What are some causes of panhypopituitarism/hypopituitarism??
Mass lesions
Treatment of sellar, parasellar and hypothalamic disease
Infiltrative disease - autoimmune, sarcoidosis
Traumatic
Vascular - Sheehan’s syndrome, pituitary tumor apoplexy
Medications - opiates, pharmacologic glucocorticoid therapy
Infectious
Genetic
Developmental
Clinical findings of panhypopituitarism
ACTH deficiency or secondary adrenal insufficiency
TSH deficiency or secondary hypothyroidism
GH deficiency in adult
Prolactin deficiency
Gonadotropin deficiency or hypogonadotropic hypogonadism
What are some diagnostic test findings in panhypopituitarism?
Low free T4 with low or inappropriately normal TSH
ACTH – Cortisol fasting, ACTH stimulation test, Insulin tolerance test
Males: insufficiency if testosterone is below reference range with low or inappropriately not increased LH and FSH
Females: insufficiency if estradiol is low with low or inappropriately not increased FSH and LH
GH – Basal IGF1, insulin tolerance test, GHRH arginine stimulation test, glucagon stimulation test
What hormone replacements are given for panhypopituitarism?
Thyroid: levothyroxine (T4), adjust dose according to free T4 and not TSH
Adrenal: hydrocortisone or prednisone (no mineralcorticoid needed)
Gonadoropins: Female = replaced with estrogen and progesterone, OCP, patch; fertility requires gonadotropins for ovulation
Male = replaced with testosterone, injections, gel, patch; fertility requires HCG injections 3x perk
GH: given as daily subcutaneous injections
What are some clinical signs of GH deficiency?
Neonate = jaundice, hypoglycemia, microphallus, traumatic deliver Child = propensity for hypoglycemia, increased fat, high pitched voice, microphallus, absent or delayed pubery, weight less affected than height, occasionally present physical defects of skull, midline craniofacial abnormalities
What are GH deficiencies noticed on the growth chart?
Usually after the first two years of life when GH is more important in growth
Weight is less affected than height
What are some diagnostic techniques for diagnosing GH deficiency in children?
Stimulus Exercise Levodopa Clonidine Arginine HCl Insulin Glucagon GHRH
What therapy is used for GH deficiency in children?
Recombinant human growth hormone (rGH) - subcut injection
- Given each evening to mimic the normal diurnal pattern of growth hormone release
- Dosing based on mg/kg/week and the etiology
How does dosing of rGH differ for a child with GH deficiency and a child with ISS (idiopatic short stature)??
True growth hormone deficiency need much smaller doses of GH than a child with idiopathic short stature – they are much more sensitive to it
