Endocrinology: Pituitary,hypothalamus, Thyroid Flashcards
What are the causes of hyperprolactenemia
I. Physiologic hypersecretion Pregnancy Lactation Chest wall stimulation Sleep Stress
II. Hypothalamic–pituitary stalk damage Tumors Craniopharyngioma Suprasellar pituitary mass Meningioma Dysgerminoma Metastases Empty sella Lymphocytic hypophysitis Adenoma with stalkCompression Granulomas Rathke’s cyst Irradiation Trauma Pituitary stalk section Suprasellar surgery
III. Pituitary hypersecretion
Prolactinoma
Acromegaly
IV. Systemic disorders Chronic renal failure Hypothyroidism Cirrhosis Pseudocyesis Epileptic seizures
V. Drug-induced hypersecretion
Dopamine receptor blockers Atypical antipsychotics: risperidone Phenothiazines: chlorpromazine, perphenazine Butyrophenones: haloperidol Thioxanthenes Metoclopramide
Dopamine synthesis inhibitors
α-Methyldopa
Catecholamine depletors
Reserpine
Opiates
H2 antagonists
Cimetidine, ranitidine
Imipramines
Amitriptyline, amoxapine
Serotonin reuptake inhibitors
Fluoxetine
Calcium channel blockers
Verapamil
Estrogens
Thyrotropin-releasing hormone
Most common pituitary hormones hypersecretion syndrome in both men and women
Hyperprolactenemia
C/f of person with hyperprolactenemia
WOMEM amenorrhoea Galactorrhoea Infertility Dec mineral bone density(chronic as it causes hypoestronegism)
Hypoestronigism
Dec libido
Wt gain
Mild hirusitism
MEN Hyperprolacteniema Dec libido Infertilty Visual loss True galactorrhoea: uncommon
Reduced testosterone .Oligospermia .Osteoporosis .Reduced muscle mass .Dec beard growth
Mainstay of treatment for cushings ds
Selective transphenoidal resection
Kallman syndrome
Kallmann syndrome results from defective hypothalamic gonadotropin-releasing hormone (GnRH) synthesis and is associated with anosmia or hyposmia due to olfactory bulb agenesis or hypoplasia .
Prevents progression through puberty.
Dec LH,FSH, estrogen,testosterone
Postpartum women with hyperprolactenemia and prominent pituitary mass
Can be Lymphocytic hypophysitis
Empty sella
Empty/partial empty Ass with inc ICP Normal pituitary fxn(rim present) Hypopotuitarism can also develop insidiously Can be result of silent infarction Filled by CSF
Pituitary apoplexy
Acute intrapituitary haemorrhagic vascular event
CAUSES
Pituitary apoplexy may occur spontaneously in a preexisting adenoma; postpartum (Sheehan’s syndrome); or in association with diabetes, hypertension, sickle cell anemia, or acute shock.
RX
High dose glucocorticoids:
Patients with no evident visual loss or impaired consciousness
Surgical decompression: significant or progressive visual loss, cranial nerve palsy, or loss of consciousness
Laron syndrome
GH insensitivity due to mutation in GH receptor.
Normal/ high GH levels
Low IGF-I levels
Sequential loss of hormone loss in adult GH defeciency
The sequential order of hormone loss is usually GH → FSH/LH → TSH → ACTH
IGF-I measurements provide a useful index of therapeutic responses but are not sufficiently sensitive for diagnostic purposes. Why
Because its level may be normal on GH def.
Contraindications to GH therapy
active neoplasm
intracranial hypertension
uncontrolled diabetes
retinopathy
Therapy in gonadotropin deficiency
MALES
Testosterone
GnRH therapy, gonadotropin: if infertility
FEMALES
Estrogen
Progesterone
GnRH , gonadotropin : infertility
Features of sellar mass lesions
*Pituitary
Hypogonadism
Hypothyroidism
Growth failure and adult hyposomatotropism
Hypoadrenalism
*Optic chiasm
Loss of red perception Bitemporal hemianopia Superior or bitemporal field defect Scotoma Blindness
*Hypothalamus
Temperature dysregulation Appetite and thirst disorders Obesity Diabetes insipidus Sleep disorders Behavioral dysfunction Autonomic dysfunction
*Cavernous sinus
Ophthalmoplegia with or without ptosis or diplopia
Facial numbness
Frontal lobe
Personality disorder
Anosmia
*Brain
Headache Hydrocephalus Psychosis Dementia Laughing seizures
Stalk section phenomenon of pituitary lesion
May compress portal vessels
Disrupting pituitary acess to hypothalamic hormones and dopamine
Leading to dec in all pituitary hormones except prolactin
Physiologic pituitary enlargement seen in
Adolocent
Pregnancy
PRL suppression by dopamine agonists does not necessarily indicate that the underlying lesion is a prolactinoma.why
hyperprolactinemia caused secondarily by the mass effects of nonlactotrope lesions is also corrected by treatment with dopamine agonists despite failure to shrink the underlying mass
mainstay of therapy for patients with micro- or macroprolactinomas
Oral dopamine agonists
Not Sx/radiation
Dopamine agonist used in pituitary prolactinoma
Cabergoline: long acting
Bromocriptine: short acting , so used in PREGNANCY
Men tend to present with larger prolactinoma tumors than women.why
Because features of male hypogonadism are less readily evident
Causes of acromegaly
*Excess GH
PITUITARY
adenoma
Men1
Mc cune albright
EXTRA PITUITARY
Pancreatic islet cell
Lymphoma
*excess GHRH
Central: hypothalamic hamartoma, christoma
Peripheral: carcinoid of chest/abdomen(MOST COMMON CAUSE OF HIGH GHRH)
Small cell lung ca
Adrenal adenoma
Medullary thyroid ca
Pheochromocytoma
Features of acromegaly
Acral bony overgrowth :
frontal bossing
increased hand and foot size
mandibular enlargement with prognathism
widened space between the lower incisor teeth
In children and adolescents, initiation of GH hypersecretion before epiphyseal long bone closure is associated with development of pituitary gigantism
Soft tissue: increased heel pad thickness Increased shoe or glove size ring tightening characteristic coarse facial features large fleshy nose
Generalized visceromegaly : cardiomegaly macroglossia thyroid gland enlargement. Upper airway obstruction
DM
colonic malignancy
________of GH-secreting adenomas is the initial treatment for most patients
Surgical resection
Not medical(only if sx fails)
Medical Rx in GH adenoma
SOMATOSTATIN ANALOGUES(dec GH so dec IGF) Acts via somatostatin SST receptor which are expressed over GH secreting tumor
octreotide
Lanreotide
S/E
Git: Transient nausea, abdominal discomfort, fat malabsorption, diarrhea, and flatulence.
Cholesterol gallstones/sludge(due to dec gb motility)
GH RECEPTOR ANTAGONIST(dec IGF ,GH remain elevated)
pegvisomant
DOPAMINE AGONIST
Suppress GH secretion
CF of cushing syndrome
Obesity or weight gain (>115% ideal body weight) Thin skin Moon facies Hypertension Purple skin striae Hirsutism Menstrual disorders (usually amenorrhea) Plethora Abnormal glucose tolerance Impotence Proximal muscle weakness Truncal obesity Acne Bruising Mental changes Osteoporosis Edema of lower extremities Hyperpigmentation Hypokalemic alkalosis Diabetes mellitus
Use of inferior petrosal venous sampling in cushing syndrome
Diatinguish bw pituitary ACTH producing adenoma from ectopic ACTH producing tumor
Level of ACTH is measured in IPS and peripheral veins in response to CRH
RX OF CHOICE FOR CUSHING DS
selective transsphenoidal resection
Drugs used in cushing syndrome
SOMATOSTATIN ANALOGUE
Pasireotide
S/e: diabetes ( supressed pancreatic secretion of insulin ,incretins) rest git
GLUCOCORTICOID RECEPTOR ANTAGOINIST
Mefiprostone
STEROIDOGENIC INHIBITORS
Metyrapone( inhibitis and 11b-hydroxylase)
Ketaconazole(inhibits CYP 450)
Nelson syndrome
Adrenalectomy in the setting of residual corticotrope adenoma tissue.
characterized by rapid pituitary tumor enlargement and increased pigmentation secondary to high ACTH.
Most common type of pituitary adenoma
Nonfunctional
Moa of AVP
V2 receptors- G protein- adenylate cyclase -inc cAMP- more insertion of AQP2
V1 receptors-phospholipase C- contraction of smooth muscle in blood vessels in the skin and gastrointestinal tract,
Drugs caused DI
Lithium Demeclocycline Methoxyflurane Amphotericin Aminoglycosides Cisplatin Rifampin Foscarnet
Causes of hyppnatremia due to inapprropriate diuresis
three different types of salt and water imbalance:
(1) an increase in total body water that exceeds the increase in total body sodium (hypervolemic hyponatremia)
Causes: CHF, cirrhosis , nephrosis
(2) a decrease in body sodium greater than the decrease in body water (hypovolemic hyponatremia)
Causes:diarrhoea , diuretic abuse, mineralocorticoid deficiency
(3) an increase in body water with little or no change in body sodium (euvolemic hyponatremia)
Cause: * nausea, cortisol deficiency
* SIADH
Level of AVP in all 3 types of hyponatremia due to inapp diuresis
Increased in all
Treatment of DI
PITUITARY DI
Desmopressin
NEPHROGENIC DI
Thiazide diutetics, amiloride
Low Na diet , PG synthsesis inhibitor
PRIMARY POLYDYPSIA
No way to correct
Desmopressin, antidiuretic will cause water intoxication because it does not inhibit urge to drink
V2 RECEPTOR MUTATION
