Mild Hyperuricemia and Subclinical Renal Damage in Untreated Primary Hypertension

• Published in: American journal of hypertension Vol. 20; no. 12; pp. 1276 - 1282
• Main Authors: Viazzi, Francesca, Leoncini, Giovanna, Ratto, Elena, Falqui, Valeria, Parodi, Angelica, Conti, Novella, Derchi, Lorenzo E., Tomolillo, Cinzia, Deferrari, Giacomo, Pontremoli, Roberto
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-12-2007; Oxford University Press; Elsevier Science
• Subjects: Adult; Arterial hypertension. Arterial hypotension; Biological and medical sciences; Blood and lymphatic vessels; Cardiology. Vascular system; Clinical manifestations. Epidemiology. Investigative techniques. Etiology; Female; Fundamental and applied biological sciences. Psychology; Glomerular Filtration Rate; Humans; Hypertension; Hypertension - complications; Hyperuricemia - diagnosis; Hyperuricemia - etiology; Kidney Diseases - diagnosis; Kidney Diseases - etiology; Male; Medical sciences; microalbuminuria; Middle Aged; renal abnormalities; renal resistive index; serum uric acid; Vertebrates: urinary system; Hypertension; microalbuminuria; serum uric acid; renal resistive index; renal abnormalities; Urinary system disease; Albumin; Metabolic diseases; Cardiovascular disease; Asymptomatic; Uric acid; Hyperuricemia; Purine; Microalbuminuria; Proteinuria
• ISSN: 0895-7061; 1879-1905; 1941-7225
• DOI: 10.1016/j.amjhyper.2007.08.010

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.
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.
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.
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.