Some CKD patients stop to output the urine, which is a bad sign to them. that
means the waste and the toxic substance can’t discharge out of the body, and the
CKD may be can worsen to a more serious stage. So it is necessary for the CKD
patients to find a way to increase their urine output.
Although the glomerular filtration rate (GFR) is very low in patients with
end-stage kidney disease (ESKD), the urine output is variable, ranging from
oliguria to normal or even above normal levels. These findings are related to
the fact that the urine output is determined not by the GFR alone, but also by
the difference between the GFR and the rate of tubular reabsorption. If, for
example, a patient with advanced acute or chronic kidney failure has a GFR of 5
L/day (versus the normal of 140 to 180 L/day), the daily urine output will still
be 1.5 L if only 3.5 L of the filtrate is reabsorbed.
It had been thought that tubular damage impaired the ability to reabsorb
sodium and water, thereby contributing to the maintenance of an adequate urine
output in this setting. However, it seems more likely that volume expansion (due
to initial sodium retention) and a urea osmotic diuresis (as the daily urea load
is excreted by fewer functioning nephrons), due in part to solute intake, play a
more important role in the persistent urine output.
In comparison, water intake (which usually determines the urine output via
changes in the secretion of antidiuretic hormone [ADH]) plays relatively little
role in regulating the urine output in advanced kidney disease. These patients
can neither dilute nor concentrate the urine normally; the range of urine
osmolality that can be achieved may vary from a minimum of 200 mosmol/kg to a
maximum of 300 mosmol/kg, compared with 50 to 1200 mosmol/kg in normal subjects.
The net effect of this ADH resistance is that variations in ADH release in
response to changes in water intake have relatively little effect on the urine
output.
If you want to know more information about the urine output, you can send
emails to kidneyhospitalabroad@hotmail.com.
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