American Association for Clinical Chemistry
Better health through laboratory medicine
Heads Up: June 12, 2008

Risk Factors for Severe Hyperbilirubinemia Among Infants With Borderline Bilirubin Levels: A Nested Case-Control Study

Results of a new study in the Journal of Pediatrics illustrate factors physicians should consider when faced with treating infants whose total serum bilirubin (TSB) levels lie within a few mg/dL of the American Academy of Pediatrics age-specific phototherapy threshold, and may be at risk for hyperbilirubinemia. Scientists at the University of California-San Francisco analyzed data from 62 infant cases and 248 infant controls with TSB between 17 and 22.9 mg/dL at 48 hours or longer after birth. They observed that the strongest predictors of TSB ≥ 25 mg/dL were gestational age, bruising, family history of jaundice, and rapid rise in TSB. A TSB increase of ≥ 6mg/dL/day doubled the risk of developing severe hyperbilirubinemia. They also saw that phototherapy was highly effective in preventing TSB.

Serum Uric Acid Is An Independent Predictor for All Major Forms of Cardiovascular Death in 28,613 Elderly Women: A Prospective 21-Year Follow-Up Study

Serum uric acid has been consistently described as a correlate for the development and progression of cardiovascular disease, but its role as a risk factor is controversial. Now, results of a recent study published in the International Journal of Cardiology suggest that serum uric acid is an independent predictor for all major forms of death from cardiovascular disease in elderly, postmenopausal women.  A multicenter team of researchers collected data from 28,613 Austrian women who had participated in the Vorarlberg Health Monitoring & Promotion Program. Their mean age was 62.3 years and they were followed for a median of 15.2 years. Serum uric acid in the highest quartile (≥5.41 mg/dL) was significantly associated with mortality from total cardiovascular disease. In subgroup analyses, serum uric acid was independently predictive for deaths from acute, subacute, and chronic forms of coronary heart disease. Serum uric acid also was significantly related to fatal congestive heart failure and stroke.

Overweight, Obesity, and Elevated Serum Cystatin C Levels in Adults in the United States

A significant percentage of U.S. adults are affected by excess weight and obesity, and associations between body mass index (BMI) and chronic kidney disease are being noted. Epidemiologic studies using biomarkers of early kidney disease—such as serum cystatin C—provide an opportunity to address this association. Looking at cross-sectional data from NHANES III researchers from Mt. Sinai School of Medicine (New York, N.Y.), the Framingham Heart Study (Framingham, Mass.), and Brigham and Women’s Hospital and Harvard Medical School (Boston, Mass.) reported in The American Journal of Medicine that a strong graded association exists between higher BMI and elevated serum cystatin C. They report that further research is needed to determine if reducing BMI can lower elevated serum cystatin C and prevalence of subsequent kidney and end-stage renal disease.