ABSTRACT. The recommended albumin (μg)/creatinine (mg) ratio (ACR) (30 μg/mg) to detect microalbuminuria does not account for sex or racial differences in creatinine excretion. In a nationally representative sample of subjects, the distribution of urine albumin and creatinine concentrations was examined by using one ACR value (≥30 μg/mg) and sex-specific cutpoints (≥17 μg/mg in men and ≥25 μg/mg in women) measured in spot urine specimens. Mean urine albumin concentrations were not significantly different between men and women, but urine creatinine concentrations were significantly higher (P < 0.0001). Compared with non-Hispanic whites, urine creatinine concentrations were significantly higher in non-Hispanic blacks (NHB) and Mexican Americans, whereas urine albumin concentrations were significantly higher in NHB (P < 0.0001) but not Mexican Americans. When a single ACR is used, the prevalence of microalbuminuria was significantly lower among the men compared with women (6.0 versus 9.2%; P < 0.0001) and among non-Hispanic whites compared with NHB (7.2 versus 10.2%; P < 0.0001). No significant difference in the prevalence of microalbuminuria between men and women was noted when sex-specific ACR cutpoints were used. In the multivariate adjusted model, female sex (odds ratio, 1.62; 95% confidence interval, 1.29 to 2.05) and NHB race/ethnicity (odds ratio, 1.34; 95% confidence interval, 1.12 to 1.61) were independently associated with microalbuminuria when a single ACR threshold was used. When a sex-specific ACR was used, NHB race/ethnicity remained significantly associated with microalbuminuria but sex did not. The use of one ACR value to define microalbuminuria may underestimate microalbuminuria in subjects with higher muscle mass (men) and possibly members of certain racial/ethnic groups.

The bleeding time is used by many nephrologists to predict risk of hemorrhage before percutaneous kidney biopsy. Developed in 1910, the bleeding time is a nonspecific test that may be prolonged in multiple disease states. When accompanied by a platelet count, hematocrit, and a thorough investigation of family or personal history of bleeding, the bleeding time is the best predictor of hemorrhagic risk in patients with kidney disease. Because there is a small but significant risk of bleeding with percutaneous kidney biopsy, a prolonged bleeding time should be treated with 1-deamino-8-D-arginine vasopressin, cryoprecipitate, estrogens, or dialysis as indicated before biopsy. Treating all patients with 1-deamino-8-D-arginine vasopressin without checking bleeding times may be cost-ineffective when compared with treating only those patients with prolonged bleeding times.

Sometimes, readily available laboratory data can provide valuable hidden information. Such is the case with the serum urea nitrogen-creatinine ratio. A normal ratio is 8:1 to 10:1. It is well known that an elevated ratio is seen in cases of prerenal or postrenal uremia. Less appreciated are the diagnostic possibilities suggested by a decreased serum urea nitrogen-creatinine ratio (ie, <8). Several clinical circumstances can lead to a decreased serum urea nitrogen-creatinine ratio.

Little information is available about either the potential beneficial or harmful effects of estrogen replacement therapy in postmenopausal women with end-stage renal disease. Although evidence supports a role for estrogen replacement therapy in postmenopausal women in the prevention of cardiovascular disease and bone loss, possible improvement in cognitive function, and the relief of menopausal symptoms, these conclusions may not be applicable to patients with end-stage renal disease, since these studies have generally excluded such women. This issue is of considerable importance since cardiovascular causes account for more than 50% of the all-cause mortality in patients with end-stage renal disease. However, estrogen replacement therapy may also have untoward effects in patients with the disease, including an increased risk of dialysis access thrombosis and potentially worsening coronary artery disease in postmenopausal patients. Furthermore, dosing of estrogens needs to be done carefully since renal excretion is important for the elimination of estrogen metabolites. Low dose or alternate day dosing in addition to monitoring estrogen levels may be warranted when prescribing estrogen replacement therapy to women with end-stage renal disease. In this review, it is our objective to analyze the evidence published in the literature so far and to weigh the risks and benefits of estrogen therapy in postmenopausal women with end-stage renal disease.