a.
What is the urine output.
i.
If the patient�s urine output is high then that signifies an inappropriate
response to hypernatremia. Hypernatremia is a state of sodium concentration
around losses of water. Losses of water could be due to sweating or osmotic
diarrhea in cases when patient is unable to keep with water intake (not enough
water vs unable to get to water). If someone is lost in a dessert sweating the
normal renal response is to conserve water and therefore put out minimal amount
of urine (very concentrated urine). If the person if producing a lot of urine in
face of hyponatremia then that signifies diabetes insipidus.
b.
How long has this been going on?
i.
You are trying to establish if this is chronic (over 48 horus) vs acute (< 48
hours) since your therapy will be tailored according to the duration of problem.
Patients who have had hypernatremia for more than 48 hours the rate of
correction of sodium should not exceed 10 meq/l in 24 hours. Within 48 hours the
brain adapts to hypernatremia. Initially, water moves down the osmotic gradient
from the cells into the interstitial space and the CSF. But with time there is
accumulation of osmoles inside the cells that pulls the water back.
Rapid
lowering of the sodium concentration once the cerebral adaptation has occurred
causes osmotic water movement into brain cells, increasing the brain size within
the hard scull cavity against which there is not much expansion. The resulting
cerebral edema can lead to an encephalopathy characterized by seizures and,
rarely, permanent neurologic damage or death
a.
Urine osmolality. Kidneys can concentrate the urine up to 1200
mosm/l. The elderly and patients with chronic kidney disease can�t
always concentrate their urine that high. But nonetheless the urine
osmolality should be relatively elevated (> 600 mosm/l)