Urinary aldosterone to creatinine ratio in cats before and after suppression with salt or fludrocortisone acetate.
BACKGROUND
The endocrine diagnosis of primary hyperaldosteronism in cats currently is based on an increased plasma aldosterone to renin ratio, which has several disadvantages for use in veterinary practice.


OBJECTIVE
To establish a reference range for the urinary aldosterone to creatinine ratio (UACR) and to determine whether oral administration of either sodium chloride or fludrocortisone acetate is effective for use in a suppression test.


METHODS
Forty-two healthy cats from an animal shelter and 1 cat with primary hyperaldosteronism from a veterinary teaching hospital.


METHODS
Morning urine samples for determination of the basal UACR were collected from 42 healthy cats. For the suppression tests, urine samples for the UACR were collected after twice daily oral administration for 4 consecutive days of either sodium chloride, 0.25 g/kg body weight (n = 22) or fludrocortisone acetate, 0.05 mg/kg body weight (n = 15).


RESULTS
The median basal UACR was 7.2 x 10(-9) (range, 1.8-52.3 x 10(-9)), with a calculated reference range of < 46.5 x 10(-9). Administration of sodium chloride resulted in adequate salt loading in 10 of 22 cats, but without significant reduction in the UACR. Administration of fludrocortisone resulted in a significant decrease in the UACR (median, 78%; range, 44-97%; P < .001) in healthy cats. In the cat with an aldosterone-producing adrenocortical carcinoma, the basal UACR and the UACR after fludrocortisone administration were 32 x 10(-9) and 36 x 10(-9), respectively.


CONCLUSIONS
Using the UACR for an oral fludrocortisone suppression test may be useful for the diagnosis of primary hyperaldosteronism in cats.
Djajadiningrat-Laanen
S C
SC
Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands. s.c.djajadiningrat@uu.nl
Galac
S
S
Cammelbeeck
S E
SE
van Laar
K J C
KJ
Boer
P
P
Kooistra
H S
HS
D000450:Aldosterone / Q000652:urine*; D000818:Animals; D002371:Cat Diseases / Q000188:drug therapy / Q000652:urine; D002415:Cats; D003404:Creatinine / Q000652:urine*; D005260:Female; D005438:Fludrocortisone / Q000494:pharmacology*; D006929:Hyperaldosteronism / Q000188:drug therapy / Q000652:urine; D008297:Male; D012965:Sodium Chloride / Q000494:pharmacology*
D012965:Sodium Chloride; D000450:Aldosterone; D003404:Creatinine; D005438:Fludrocortisone