D/o of the posterior Pituitary gland Flashcards
The posterior pituitary stores
ADH and oxytocin
The paraventricular and supraoptic nuclei of the hypothalamus synthesizes
Arginine vasopressin or ADH
ADH regulates the amt of water that is reabsorbed at the lvl of
Collecting duct of the kidney
Principal variable controlling ADH secretion
Osmotic pressure
Second major stimulus for ADH secretion
Volume depletion
If ADH is decreased what happens to urine volume
Increased urine volume
What happens to serum osmolarity when there’s high osmotic pressure?
High serum osmolarity
Characterized by production of dilute urine in excess of 3L/24 hours (>40 ml/kg/24 hours in adults; >100 ml/kg/24 hours in infants)
Diabetes insipidus
Clinical manifestations of Polyuria, excessive thirst and polydipsia
Diabetes insipidus
What is the normal response for a concentrated plasma
To produce a concentrated urine
Destruction of how many percent of ADH secreting neurons is required to produce central DI
80%
What is the pathophysiology of Nephrogenic Diabetes insipidus?
Renal resistance to antidiuretic action of VP, there’s normal production of ADH
This is characterized by inappropriate, excessive water drinking
Dipsogenic DI
This is a result of deficient osmoregulation of ADH secretion
Hypothalamic DI
Most common form of DI
Post traumatic/surgical
Hypothalamic DI in pregnancy is due to
Placental vasopressinase activity decompensating previously antidiuretic capacity through increased ADH degradation
Gold standard for diagnosing DI
Water deprivation test
If plasma osmolality is grater than 290 mOsm/kg after dehydration and the urine osmolality is less than 300mOsm/kg this is a diagnosis of
HDI, this means that the kidney is responsive to ADH and there’s only a deficiency in ADH
A failure to increase urine osmolality above 300mOSM/kg after dehydration and there’s no response to DDAVP, what type of DI is this
NDI
If there’s appropriate urine conc during dehydration without significant rise in plasma osmolality this could be what type of DI
Dipsogenic DI
Treatment of choice for DI
DDAVP
Inappropriately high levels of ADH relative to the prevailing osmolality
SIADH
Rare but serious complication of hyponatremia and its treatment
CNS demylenitaion
Rapid correction of sodium concentration could lead to
CNS demylenitaion (central pontine myelinolysis)
Hyponatremia is accompanied by what levels of plasma osmolality in SIADH
Low plasma osmolality
Plasma sodium concentration that is needed to achieve when treating SIADH
125 mmol/L (the normal volume is 135-145, just slowly correct sodium to prevent CPM)
T or F in SIADH the renal and adrenal function is compromised
F it’s normal
