Uric Acid Control in Advanced Chronic Kidney Disease in a Southeastern US Urban Cohort

Tibor Fülöp, MD, PhD; Christian A. Koch, MD, PhD, MACE; Lindsey T. Norris, MD; BetzaidaRodríguez, MD; Tibor Szarvas, PhD; Zsolt Lengvárszky, PhD; Éva Csongrádi, MD, PhD; Mehul P. Dixit, MD


South Med J. 2018;111(9):549-555. 

In This Article


The cohort consisted of middle-aged to older adult patients with a mean age of 62.1 (11.6) years and an eGFR of 23.8 (11.3) mL· min−1 · 1.73 m2; 45.6% of them were female and 68.4% African American. Stratifying according to estimated renal function, 34 enrollees had eGFR <15 mL· min−1 · 1.73 m2, 51 enrollees had eGFR of 15 to 30 mL· min−1 · 1.73 m2 and 29 with eGFR >30 to 45 mL· min−1 · 1.73 m2. The cohort's mean UA level was 7.7 (2.49) mg/dL (range 3.1–16), whereas the mean allopurinol dose was 192 (99) mg/day (range 50–450). Further details of the cohort's characteristics, including demographics, anthropometrics, key laboratory results and comorbidities can be gleaned from Table 1. Approximately one-third (35.1%) of the subjects had an acceptable UA level (≤6.5 mg/dL); even less (21.1%, 24/114) had excellent (≤5.5 mg/dL) UA control. Urine pH was <6 in 60.5% of the cohort. Boxplots of urine pH, UA levels and allopurinol doses are shown in Figures 1 to 3.

Figure 1.

Distribution of urine pH in the cohort.

Figure 2.

Serum uric acid results in milligrams per deciliter.

Figure 3.

Allopurinol dose in milligrams per day.

Significant univariate correlates of allopurinol doses, UA level and urine pH are shown in Table 2. Significant univariate correlates of the administered doses of allopurinol were weight (r 0.317, P = 0.001), BMI (r 0.313, P = 0.001) and female sex (r −0.198, P = 0.035). With increasing the dosage of potassium-sparing diuretics, allopurinol doses were more likely to be higher (r 0.344; P = 0.0001) but none of the other medication classes in our database affected urine pH or serum UA levels (data not shown). Of note, no effect of allopurinol was evident on hemoglobin (P = 0.140). The graphic relation between allopurinol dosage and race-adjusted eGFR is shown in Figure 4. During logistic regression analysis with stepwise selection, only weight (β 0.313, P = 0.001) and female sex (β −0.190; P = 0.039) proved to be predictive of the allopurinol dose (Table 3). On the cohort's achieved achieved UA level, however, only the BMI (β 0.271, P = 0.006) and allopurinol doses (β −0.258, P = 0.009) had an independent effect (Table 3). During sensitivity analysis, when analyzing enrollees according to the three eGFR categories (eGFR <15, 15–30, and >30–45 mL · min−1 · 1.73 m2), the effect of BMI on allopurinol dose was persistent in the eGFR <15 and >30 to 45 categories (P = 0.044 and 0.025, respectively) but not in the eGFR 15 to 30 mL· min−1 · 1.73 m2 range; for UA, it was BMI (P = 0.006) and allopurinol dose (P = 0.020), but observed only in eGFR 15 to 30 mL· min−1 · 1.73 m2 category.

Figure 4.

The relation between estimated glomerular filtration rate in milliliters per minutes per 1.73 m2 and serum uric acid levels in milligrams per deciliter. GFR, glomerular filtration rate.