Preanalytical determinants of total and free prostate-specific antigen and their ratio: blood collection and storage conditions.

glucose, calcium, chloride, and uric acid—as demonstrated by the kurtosis and skewness coefficients and by the Kolmogorov–Smirnov test. The fetal reference intervals for sodium, potassium, urea nitrogen, creatinine, lactate dehydrogenase, uric acid, and magnesium are very close to those of infants. For glucose, aspartate aminotransferase, alanine amino-transferase, cholesterol, and triglycerides, the fetal reference intervals are shifted to much below those of adults. The fetal reference interval for total bilirubin is lower than that of infants but higher than that of adults. The lower limit of the fetal reference interval for calcium was below that of adults, but the upper limits of the fetal reference interval for chloride, inorganic phosphorus , and direct bilirubin were higher. The interval for enzymatic activity of ␥-glutamyltransferase was higher than that in both infants and adults. Recently, Perkins et al. [8] reported reference intervals for 21 clinical chemistry analytes determined in plasma obtained from arterial and venous umbilical cord blood from healthy term infants after delivery but before pla-cental expulsion. Except for K, Ca, P, Cl, uric acid, and ␥-glutamyltransferase enzymatic activity, our findings are similar to those they reported for healthy term infants. We are not able to fully explain these differences; presumably they are related to the different size and composition of the fetal reference populations, given that our adult reference intervals are closely similar to those of Perkins et al. In conclusion the analysis of our data obtained for 18 analytes suggests that the fetal reference intervals are similar to those of infants only for urea nitrogen, Na, K, creatinine, lactate dehydrogenase, uric acid, and Mg. For those analytes that change as a function of gestational age, knowledge of the fetal reference intervals according to stage of pregnancy is important, particularly when therapy is necessary (e.g., albumin infusions in nonimmune hydrops). Fetal blood sampling during pregnancy with use of a needle guided by ultrasound. A study of 606 consecutive cases. Prostate-specific antigen (PSA) is present in serum in several forms [1]. About 70 –90% of total PSA (t-PSA) is Fig. 1. Behavior of 5 analytes that change with gestational age: albumin, total protein, CK, CHE II, and ALKP.