Firecracker - Electrolytes Flashcards
hyponatremia - value
<135
SIADH - explanation
inapproriate secretion of ADH –> water retention, hyponatremia
Causes of SIADH
Organic CNS disease: Meningitis, encephalitis, cerebrovascular accident, head trauma
Acute Psychosis
Tumors, especially small cell lung cancer (paraneoplastic)
Other pulmonary diseases (pneumonia, acute respiratory failure)
Meds that cause SIADH
Antidepressants (SSRIs) and Antipsychotics
Narcotics and NSAIDs
Chlorpropamide
hyponatremia (big picture) =
increase in intracellular osmolality relative to extracellular osmolality.
As result, water shifts into cells,
and in the CNS can cause brain edema.
hyperglycemia & hyponatremia
Glucose is osmotically active, and it draws water into the extracellular space. Increased vascular volume increases diuresis, leading to hyponatremia.
Corrected Serum Sodium
Measured serum sodium + 0.016 * (Serum glucose – 100)
symptoms of hyponatremia
nausea and malaise. Symptoms can progress to lethargy, and confusion.
Na <115
seizures + coma
plasma osmolality in hyponatremia
Plasma osmolality is normally low in hyponatremia. The exception is in the case of osmotically active solutes, such as glucose, sorbitol, and mannitol.
urine in hyponatremia
kidneys should secrete a dilute urine (< 100 mOsm/L) in response to hyponatremia. If the urine is not diluted, it is suggestive of SIADH.
sodium correction
sodium correction should not exceed 12 meq in 24 hour
raise the serum sodium level by 1 meq per hour the first few hours to a level of 120 meq/L.
treatment of euvolemic hyponatremia
fluid restriction, loop diuretics ( to lower the urine osmolality), and/or salt tablets. The use of tolvaptan (Samsca) can also be prescribed in cases of refractory hyponatremia
Samsca
refractory hyponatremia. It causes a free water diuresis through its action on the aquaporin receptor.
hyperkalemia value
> 5
