CVD & Electrolyte Imbalances Flashcards
(92 cards)
Where in the body is ADH produced & secreted
produced by magnocellular neurons in the hypothalamus; secreted by the posterior pituitary gland
ADH drives sodium & water reabsorption along which parts of the nephron?
TAL & CD
Hypernatremia is clinically defined as what?
Serum Na concentration > 145 mmol/L
What are the 3 main causes of Hypernatremia?
Diabetes Insipidus; Inadequate bodily fluid volume; hyperglycemia
How does hyperglycemia cause hypernatremia?
at high concentrations, glucose can act as an osmotic diuretic and trap free water in the lumen to be excreted through urine
What is the mechanism of Dehydration-induced Hypernatremia?
Hyperosmotic plasma relative to the renal luman; hyperosmotic urine
How does nephrogenic diabetes insipidus affect urine osmolarity?
the urine osmolarity does not change and will stay the same even if the water deprivation progresses
What are secondary causes of hypernatremia?
orthostatic hypotension; pneumonia; tachycardia
What is the drug of choice to treat central diabetes insipidus?
desmopressin
What drugs are 1st line for management of nephrogenic DI?
Thiazides; amiloride
What diseases have strong correlation w/ nephrogenic DI?
amyloidosis; sarcoidosis; SLE; malignancy; PKD; V2-receptor defects
How is hyponatremia clincialy defined?
serum Na concentration < 135 mM
What recreational drug has been shown to cause acute hyponatremia?
MDMA (Ecstasy)
How is factitious hyponatremia clinically defined?
Plasma osmolarity > 295 mOsm/Kg
What causes factitious hyponatremia?
hyperglycemia & mannitol; dilution of serum Na via osmosis
If a pt. has normal plasma osmolality but is hyponatremia what causes would be at the top of your DDx?
hyperproteinemia; hyperlipidemia;l bladder irrigation; pseudohyponatremia b/c Na serum con. is being displaced by increased occupancy of lipids and proteins both of which do not contribute to plasma osmolality
How is true hyponatremia clinically defined?
plasma osmolality < 280 mOsm/kg
What is happening with Hypotonic Hypervolemic Hyponatremia?
volume overload causes ECF to be hypotonic relative to the ICF; therefore water is going to move from the ICS to the ECS causing edema
What are the main causes of hypotonic hypervolemic hyponatremia?
CHF (decreased renal perfusion from low CO), Cirrhosis (vasodilation), Nephrotic syndrome (hypoalbuminemia), renal insufficiency (impairment of free water excretion)
What can cause hypotonic hyponatremia when ECF volume is normal?
SIADH, hypothyroidism; adrenal insufficiency
What are the clinical hallmarks of adrenal insufficiency?
hypotension or normal BP; skin hyperpigmentation (elelvatd MSH stimulates melanin synthesis in epidermal melanocytes) hyperkalemia (almost always due to hypoaldosteronism)
How do diuretics affect volume of the ECF?
decreases ECF volume
How will Insensible Loss & diaphoresis affect ECF?
it will decrease ECF
Secretory Diarrhea is caused by what pathogen and how will it affect the ECF volume?
cholera; will decrees ECF volume