The difficulties to judge the "real" potassium level from serum
analysis have been discussed at various occasions. Now we seem to be
hit ourselves.

History:
This cat adopted me five years ago and we are very much in love since.
Right then, I discovered symtpoms of CRF (high water intake,
occasional vomiting). Crea was about 2.2 mg/dl and on a later check
2.64.
I fed the best food available in many smaller offerings, gave high
qualitiy salad oil (2-3g after meals) and encouraged to drink.
During last year, the vomiting seemed to have disappeared.
He always had somewhat hard stools, but last week (19+ years, 4 kg),
he suffered from severe congestion, and yesterday we were busy from
9pm to 3am to release a hard rock.

Since about 1.5 weeks he began to reduce food intake, whereas he still
drinks and devours his salad oil more often than not.

3 days ago we have been at the vet, to do a check up and (much feared)
to determine wether the beloved cat had travelled to the end of his
road.

Findings:
x-ray (1 taken lying on back and 1 on side) seems to indicate some
water in his lung. Kidneys normal.

Today the blood panel arrived. Crea is 1.89, well below limit of 2.0
mg/dl.
I'll just name the out of range ones with the ranges given in brackets
[]:
++ BUN                     51    [10 - 33 mg/dl]
+   Bilirubin                0.33  [ <0.3 mg/dl ]
+   Alk. Phosphatase   111   [ <105 U/l]
+   GLDH                   11.4  [ <9 U/l ]  
-   Triglycerides          24    [ 44 to 105 mg/dl]
-   Leukocytes            3.6   [  6 to 11 G/l]
--  Erythrocytes         3.06  [ 5 - 10 T/l]
-   Hemoglobin            5.87  [ 9 - 15 g/dl]
-   Hematokrit            21     [ 28 - 45 %]
++ MCV                    69     [40 - 55fl]
+   HbE                    19      [13 - 17 pg]
--  MCHC                  28     [31  - 35 g/dl]
-   Lymphocytes       864     [1000 - 6000 /ul]
-   Segment-cored   2736    [3000 - 11000 /ul]
and, as the reason of this posting

   Potassium           4.2     [3.0 - 5.0 mmol/l]

With my last kidney patient, it had been 3.8 half a year before we had
to let her go (age 21+), and the other vet had never mentioned it.

Now, the recommendation is, to support the heart and eventually reduce
the water in the lung by giving (1/day) 25ug of Lanitop mite, which is
Metildigoxin, a heart active glycoside derived from the plant
digitalis lanta. The accompanying sheet says (among lots of others):
Not to be applied in case of hypokalemia.

During the last years I used to occasionally add 100mg of Potassium
gluconate once a day to the cats meal, which is much below the doses I
found mentioned. This seemed to have a positive effect concerning
agilitiy and alertness (if we give any weight to such observations).

Now, between a rock and a hard wall: What should I do?
Thanks in advance for your patience and eventual replies,
H.