Lecture 45 April 4th-endocrine

1DDX: LECTURE 45 – APRIL 4TH, 2007 Endocrine (1), Hypothalamus and Pituitary Page 1 GH stimulates prolactin, TRH stimulates Prolactin, GnRH stimulates prolactin. Somatostatin and Dopamine are inhibitory. Distinct areas in Hypothalamus Optic chiasm right next to pituitary. CN III, IV, VI. Posterior pituitary only stores hormones. PRL will be seen in pituitary adenoma Page 2 Anterior pituitary hormones may have more dramatic impact when FSH and LH are low. GH: glucagons-like effects. GH: Acutely, GH has insulin-like activity to counter the glucagon released in hypoglycaemia. Interfereing factors: argentine, insulin and glucagon are in large amounts. Prolactin: See nipple discharge TSH: Lesion at thyroid and TSH gets no response. Thyrotoxicosis is a type hyperthyroidism FSH and LH: Most pituitary hormones have diurnal variation. Spike in early morning: this is why we do 24 hour urine sample. PCOS = polycystic ovarian syndrome Hematuria: interferes with 24 hour urine test. Page 3 Emesis happens in sympathetic state. Body produces ADH in sympathetic state. Trying to keep fluid in the system. DM: different is that one is nephrogenic: lesion at level of KI or neurogenic, lesion is at level of brain. SIADH: syndrome of inappropriate ADH. Headaches: anything over 10mm (macro) starts pressing on structure *Signs and symptoms of a mass lesion, such as headaches, visual field defects are the biggest clue to pituitary tumour. If 1 hormone: it is at level of gland. Bilateral hemianopia: loss of vision on outer halves of visual field Sclerosis: change in skin texture (thickening/hardening) Chronically high ACTH in Addison’s, Cushings. Myxedema: hypothyroid Hypothalamus mediates primitive functions. Endorphins and enkephalins are hypothalamus-mediated. Page 4 Generalized Adult Hypopituitarism Rare for pituitary lesion to only effect ECTH. “pituitary dwarfism” is from birth Loss of muscle mass and strength in isolated GH deficiency. Panhypopituitarism normally results from Sheehan’s syndrome. Low anterior pituitary hormones across the board. Pituitary apoplexy normally not panhypopituitary Empty sella syndrome: visual problems are insidious. Headache: chronic and increasingly severe DDX LECTURE 45, APRIL 4TH, 2007 – PAGE 1

Replacement of hormones: for life. Tumours and adenomas: outside pituitary Primary hypopituitarism: lesion is at level of pituitary Apoplexy = infarction Generalized Adult Hypopituitarism Anorexia nervosa: GH and cortisone are increased because you are in chronic sympathetic state. Myotonia dystorphica: type of muscular dystrophy. Page 5 Galactorrhea: because so many releasing hormones trigger prolactin. FSH/LH are decreased because they are inhibited by prolactin. Dopamine abnormalities: dopamine inhibits prolactin Chest wall lesions: from trauma to breast. Phenothiazines: diuretics Page 6 Gigantism and Acromegaly: Increased risk of malignancy in GI because rate of turnover is increased. Chronically high GH has an anti-insulin, glucagon effect. Non-functioning pituitary adenomas: impingement. Page 7 Primariy DI: not producing ADH Diagnosis: No change in symptoms. Still excessive amount of urin in 24 hours (5-7 L) Diuretics have negative feedback effect on ADH. Vasopressin-sensitive: lesion at ADH Info about Growth Hormone: GH released in reponse to hypoglycaemia, starvation, anorexia GH has insulin-like activity acutely Low blood sugar, insulin decreases and GH is decreased. Sugar leaves cells and becomes available for brain function. When you see more than 1 endocrine problem, keep hypopituitarism in mind.

DDX LECTURE 45, APRIL 4TH, 2007 – PAGE 2