Creatinine-based glomerular filtration rates and microalbuminuria for detecting metabolic abnormalities in US adults: The National Health and Nutrition Examination Survey 2003-2004

Background/Aims: Guidelines suggest searching for metabolic complications of chronic kidney disease when glomerular filtration rates (GFR) or urinary albumin tests are abnormal. This study aimed to quantify diagnostic test characteristics of these measures for detecting metabolic abnormalities. Methods: Subjects were participants aged ≥20 years (n = 7,778) in the US National Health and Nutrition Examination Survey 2003-2004. Low GFR was defined as creatinine-based estimate <60 ml/min per 1.73 m²; abnormal urinary albumin-creatinine ratio as ≥20 mg/dl in men, ≥30 mg/dl in women; and metabolic abnormalities as abnormal potassium, hemoglobin, bicarbonate, phosphorus, or parathyroid hormone levels. Results: Of adults, 5.66% had low GFR and 8.14% abnormal urinary albumin-creatinine ratio. Overall, 15.09% had ≥ one metabolic abnormality, as did 34.07% with low GFR (p < 0.0001) and 24.27% with abnormal urinary albumin-creatinine ratio (p = 0.0021). Considered as a diagnostic test, the sensitivity, specificity, and positive and negative predictive values of low GFR for detecting ≥1 metabolic abnormality were 0.13, 0.96, 0.34, and 0.86, respectively. Corresponding values for abnormal urinary albumin-creatinine ratio were 0.13, 0.92, 0.24, and 0.86. Conclusions: A policy of searching for metabolic complications in every adult with low GFR or microalbuminuria has limited diagnostic yield.