715 BRIEF REPORTS Table 2. proteins* Correlations between serum uric acid (SUA) and serum No. persons tested Correlation coefficient Probability? Men Women Total 156 169 325 0.1697 0.1768 0.1300 0.05 0.05 0.02 Men Women Total 149 167 316 0.0905 0.1139 —0.0275 NS NS NS 0.1957 0.02 Total protein Total globulin Albumin Men 151 Women 168 Total 319 0.1412 0.2541 0.05 0.01 * Outlying values (arbitrarily selected as a SUA >9.5 mg/dl for men and >8.5 mg/d] for women) were excluded in this analysis. + NS = not significant. of the U.S. population followed at BNL (4.4 + 0.5 SD [n = 319], versus 4.7 + 0.4 SD, respectively), whereas total globulin levels were higher in the Marshallese (3.7 + 0.6 SD [n = 316], versus 2.6 + 0.7 SD). Outlying values (arbitrarily selected as a SUA >9.5 me/d| for men and >8.5 mg/dl for women) were excluded in these correlations because the purpose was to study the effect of protein binding on normal SUA in the general population. Other findings included: 1) a significant correlation between SUA values and BMI (men: r = 0.230 [n = 110], P< 0.02; women: -r = 0.274 [n = 137], P < 0.01). a significantly higher mean SUA value in hypertensive subjects than in nonhypertensives (6.7 mg/dl [n = 32], versus 6.0 mg/dl [n = 356], P = 0.02). When values of obese individuals were removed, however, this difference was lost (6.3 mg/dl [n = 16], versus 6.0 mg/dl [n = 262], P = 0.54). 3) a lower mean SUA value in diabetic subjects than in nondiabetics, but the differ—— 2 ence was not statistically significant (5.7 mg/dl [n = 35], versus 6.1 mg/dl [n = 353], t = 1.48, df = 41, P = 0.15). — 4) a difference in SUA values for men according to island of residence (f [3,175] = 3.03, P = 0.03), with the population centers having higher mean values than the remote islands; for women, P = 0.09. 5 no significant difference, by one-way analysis of variance, between the groups ex- posed to radiation and those not exposed (Table 1). Gout was present in 2 men at the time of SUA testing, and 2 more developed clinical gout over the ensuing 5 years, giving a current prevalence of 1.7%. No patient had gouty tophi. Discussion. Uric acid is tightly bound to an a,- a-globulin, although only in small quantities (about 0.1-0.2 mg/dl) (9). Other protein binding is considered to be loose, thus permitting glomerular filtration of uric acid. The finding of a significant correlation between SUA and albumin values suggests that albu- min is one determinant of SUA levels. This is supported by in vitro studies indicating | gm/dl of albumin will bind 0.6 mg/dl of uric acid (10). Data in this report also show that the elevated globulin levels often encountered in tropical areas do not contribute significantly to the SUA level, and thus do not explain the higher values found in the Marshallese. Anotherfactor influencing SUA is menopause, at which time the SUA level increases (11). In the present series, 67 of 196 women (34.2%) were over age 45. The mean SUA valuefor all women was5.6 mg/dl, whereasthe value was 5.2 mg/dl for women =45 years of age. This difference is reflected in the cumulative frequency distribution (Figure 1). The distributions of SUA values in these Micronesians were not bimodal, a point that has been noted by others (2,4). Instead, the cumulative frequency distributions, when graphed on probability paper, were nearly straight lines for men and for women under 46 years of age (Figure 1), suggesting that the SUA distribution is Gaussian rather than leptokurtic (12). It is therefore unnecessary, when selecting a ‘‘normal’’ range, to correct for skewness by using percentile cutoffs. For Marshallese men the normal range of SUA (based on the mean +2 SD) ts 4.0-9.2 mg/dl, and for women under 46 years of age, 2.8-7.6 mg/dl. The upper limits of normal are at least | mg/dl higher than those reported in U.S. studies using nonenzymatic SUA assays. A positive correlation between SUA values and both body weight and ponderal index has been reported (13). The present data indicate a similar correlation with another index of obesity, the BMI. The lack of correlation of hypertension with SUA levels (after deletion of values from obese persons), and the lower mean SUA levels in diabetics than in nondiabetics has been reported in other populations (14). While men had higher SUA values in the population centers than on the remote islands, we have insufficient data to