Mild hyperuricemia and subclinical renal damage in untreated primary hypertension.
BACKGROUND
Subclinical renal damage and hyperuricemia are not uncommon in patients with primary hypertension. Whether mild hyperuricemia reflects a subclinical impairment of renal function or contributes to its development is currently debated. We investigated the relationship between serum uric-acid levels and the occurrence of early signs of kidney damage.


METHODS
Four hundred eighteen patients with primary hypertension were studied. Albuminuria was measured as the albumin-to-creatinine ratio, and creatinine clearance was estimated by the formula of Cockcroft and Gault. Interlobar resistive index and renal abnormalities, ie, the renal volume-to-resistive index ratio, were evaluated by renal Doppler and ultrasound.


RESULTS
Uric acid was directly related to resistive index (P = .007) in women and to albuminuria (P = .04) in men, and was inversely related to the renal volume-to-resistive index ratio in both men (P = .005) and women (P = .02). Patients with uric-acid levels above the median showed a higher prevalence of microalbuminuria (14% v 7%, P = .012) and of renal abnormalities (41% v 33%, P = .007). Moreover, when creatinine clearance was taken as a covariate, patients with increased uric-acid levels showed higher albuminuria and resistive indices, and a lower renal volume-to-resistive index ratio. Even after adjustment for several risk factors, each standard deviation increase in serum uric acid entailed a 69% higher risk of microalbuminuria, and a 39% greater risk of ultrasound detectable renal abnormalities.


CONCLUSIONS
Mild hyperuricemia is associated with early signs of renal damage, ie, microalbuminuria and ultrasound-detectable abnormalities, regardless of the glomerular filtration rate in primary hypertension.
Viazzi
Francesca
F
Department of Internal Medicine and Cardio-Nephrology, Azienda Universitaria Ospedale San Martino, University of Genoa, Genoa, Italy.
Leoncini
Giovanna
G
Ratto
Elena
E
Falqui
Valeria
V
Parodi
Angelica
A
Conti
Novella
N
Derchi
Lorenzo E
LE
Tomolillo
Cinzia
C
Deferrari
Giacomo
G
Pontremoli
Roberto
R
D000328:Adult; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D006973:Hypertension / Q000150:complications*; D033461:Hyperuricemia / Q000175:diagnosis* / Q000209:etiology*; D007674:Kidney Diseases / Q000175:diagnosis* / Q000209:etiology*; D008297:Male; D008875:Middle Aged