PcimOlki pisze:[...]
Wydaje mi się, że zasadniczym celem badań przesiewowych jest wykrycie nieprawidłowości, nie potwierdzania stanu prawidłowego. [...]
Tak w ramach wczesnego ostrzegania poszukuje wszelakich informacji na temat możliwości zagęszczania moczu w przypadku kotów z niesprawnymi nerkami. W przeciwieństwie do CREA która u mnie (i nie tylko) skacze dość dziwnie i jak na razie niewytłumaczalnie, ciężar właściwy (SG) jest logiczny. Jakiekolwiek picie wody mojej kotki przy normalnym jedzeniu oznaczałoby brak zdolności zagęszczania większej niż gdzieś 1.030-1.045 (w zależności ile mi się uda wody wcisnąć) natomiast picie podczas jednodniowej głodówki to poniżej 1.060.
Z tego co wyczytałem u psów brak zdolności zagęszczania często poprzedza azotemię, u kotów już tak różowo nie jest.
W schemacie IRIS jest iż u psów i kotów z azotemią nerkową SG jest zazwyczaj poniżej 1.030
Wg. innych źródeł:
1) Some cats with primary renal failure can concentrate urine to 1.045 or greater. [...] Studies of partially nephrectomized cats with remnant kidneys have revealed that animals with less than 25% functional nephrons could concentrate their urine significantly higher than SG = 1.040
2) Based on the studies on partially nephrectomized cats it has been concluded that cats might become azotemic before they lose their ability to concentrate urine (Ross and Finco 1981). This conclusion was questioned in naturally occurring renal disease where a study with a large number of cats suffering from renal insufficiency revealed that most of the cats were not able to concentrate urine to a specific gravity of more than 1.035 (Elliott and Barber 1998).
Some cats in our study showed normally concentrated urine despite considerably reduced GFR, but none of them had a creatinine level higher than 200 μmol/l. [...] Several cats with markedly reduced GFR produced urine with a specific gravity of 1.050–1.060, but cats with a GFR lower than 18 ml/min/m2 or a creatinine higher than 200 μmol/l did not produce urine with a specific gravity higher than 1.035.[...]
Based on our data from this small number of cats, we conclude that urine concentration ability in cats is maintained at a higher degree of renal damage than in dogs,as has been shown in a study with partially nephrectomized cats (Ross and Finco 1981). But as indicated by comparison of urine specific gravity and creatinine levels, cats with naturally occurring renal disease lose their urine concentration ability soon after azotemia has started. Elliott and Barber (1998) used in their study a creatinine level above 180 μmol/l as inclusion criteria. Based on our data, this creatinine level reflects an already considerable reduction in GFR and therefore the finding that cats had lost their ability to concentrate urine is not surprising.