Anterior pituitary Flashcards
Normal reasons for enlarged pituitary (nonthreatening)
Puberty and 3rd trimester of pregnancy (prep for lactation)
Common modes of presentation of pituitary problems
Incidental finding, Mass effects, Hormone excess, Hormone deficiency
Identify two symptoms that result from pressure effects of a pituitary mass
Headaches (stretch the dura) and vision - From chiasmal compression, Loss of peripheral vision, tunnel vision (more severe), Pale optic disc (from ischemic). Rarer: diplopia from compression of cranial nerves, Rhinorrhea from CSF leak (surgery), Seizure, mental changes
Table of ant pituitary hormone, target hormone, stimulatory signal from hypo and inhibition
Table. Dopamine is important.
How do you measure hormone levels?
Basal vs. dynamic testing; Always measure target gland hormone (Cortisol, Free T4, IGF-1, Testosterone, Estradiol). In some, measure pituitary hormone (LH/FSH, PRL, TSH). In others, pituitary hormone levels highly fluctuating, often unreliable (GH, ACTH)
DDX for pituitary mass
*Pituitary adenomas (most common); Meningioma; Craniopharyngioma (children); Granulomatous disease, eg. sarcoidosism; Infiltrations, eg. histiocytosis and hemochromatosis; Infections, eg. tuberculosis, abscess, syphilis; Pituitary hyperplasia (puberty, preg), Autoimmune hypophysitis
Classification of pituitary adenoma and pathology
Macroadenoma: >1 cm; micro: < 1. Almost always benign. Prolactinoma most common. Can be specific for others
List common causes of hypopituitarism
Starred are most common. *1. Pituitary and parapituitary tumors.*2. Radiotherapy *3.Trauma (car, sports). 4. Infarction (pituitary apoplexy). 5. Infiltrations, eg. sarcoidosis. 6. Infections, eg. tuberculosis. 7. Sheehan’s syndrome
Describe the pathology of hypopituitarism. What are the deficiencies from most common to least?
3/4 of pituitary must be destroyed before endocrine deficiency becomes apparent. Acronym: Go Find The Adenoma Please: GH deficiency and hypogonadism (FSH/LH) deficiency appear early, followed by TSH and ACTH deficiency, Prolactin deficiency least common
Manifestations of gonadotropin deficiency
Women (symptoms of estrogen deficiency: Amenorrhea, infertility, dyspareunia (painful intercourse), breast atrophy, loss of secondary sexual hair. Men (symptoms of testosterone deficiency): Poor libido and impotence, infertility, soft testicles, loss of secondary sexual hair
Manifestations of GH deficiency
Adults: Reduced muscle mass, Abdominal obesity, Lipid disorder, Osteopenia. Children: Short stature. Metabolic effects: Abnormal lipids, more fat mass / lower muscle mass, lower bone mass
Manifestations of TSH deficiency
Adults (hypothyroid symptoms): Decrease in energy, Constipation, Sensitivity to cold, Dry skin, Weight gain. Children: Growth retardation
Manifestations of ACTH deficiency
Symptoms of cortisol deficiency: Weakness, Tiredness, Dizziness on standing, Pallor (not hyperpigmented), Hypoglycemia
Describe how to investigate suspected hypopituitarism. What tests?
Good history (unlikely in women with normal menses); IGF-1 (commonly low); Testosterone/estradiol with FSH; normal FSH in menopausal women suggests hypopituitarism; Cortisol, may need stimulation test; Free T4 with TSH; Prolactin can be high (stalk effect). Provocative tests: GnRH stimulation, TRH stimulation, Insulin tolerance (GH, cortisol, ACTH). MRI and visual field.
Common treatments for hypopituitary
Adrenal (hydrocortisone, prednisone, dexamethasone), Thyroid (thyroxine), Gonadal (testosterone/estrogen). Treat underlying disease (eg. Medical therapy for prolactinoma, transsphenoidal surgery + medical and/or radiotherapy for tumor)
Regulation and action of GH secretion
Made by somatotrophs. Secretion: Pulsatile, Circadian Rhythm, Stress-induced secretion, Negative feedback by IGF-1. Picture
What does somatomedin do? (2nd half of chart)
Picture
Pathology of GH excess
Most are from GH secreting adenoma; Slowly progressive disease; Onset of symptoms commonly ten years earlier
List the clinical manifestations of acromegaly
Gigantism in children, Acromegaly in adults: Increase in ring and shoe size. Coarse facial features, prognathism (protruding jaw) and prominent forehead. Soft tissue swelling, eg. spade-like hand, macroglossia (large tongue). Excessive sweating. Sleep apnea, snoring, daytime somnolence; Headache, Nerve entrapment, eg. peripheral neuropathy or carpal tunnel syndrome, Decreased energy, Osteoarthritis, Erectile dysfunction with decreased sex drive, Multinodular goitre, Hypertension, Diabetes or impaired glucose tolerance, colonic polyps, back pain, sciatica
Describe the workup of a patient suspected of having acromegaly
Glucose tolerance test (GH normally suppressed by it), Plasma IGF-1, Prolactin: increased by stalk effect or tumor; Other pituitary hormones: may be reduced secondary to mass effect, MRI, Visual field
Identify treatment options for acromegaly
Surgery (can affect other hormones tho), Analogues (sandostatin, GHr antagonist - $$), radiotherapy
Regulation of prolactin secretion
Increase: TRH (thyrotropin release hormone), Stress, pregnancy, estrogen, lactation, nipple suction. Inhibit: dopamine
Describe the clinical manifestations of hyperprolactinemia
Hyperprolactinemia is most common pituitary disorder. Dopamine is not inhibiting it. Female patients: Most have small tumors (microadenomas), Galactorrhea 30-80%, Menstrual irregularity and infertility, Symptoms of large tumors (less common). Male patients: Usually large tumors (macroadenomas); Impotence and reduced libido, galactorrhea not common; Symptoms of large tumors (Visual field abnormalities, headache and hypopituitarism)
Provide a differential diagnosis for hyperprolactinemia
Prolactinoma or Other hypothalamic/pituitary disorders: Pituitary mass -> compression of portal tract -> stalk effect (defective dopamine delivery) or GH-secreting tumor (can co-secret prolactin or stalk effect); hypothyroid; drugs;
