Blood Bilirubin Concentrations Research Articles

FETAL AND NEONATAL BILIRUBIN CONCENTRATIONS IN HEMOLYTIC DISEASE 870

OBJECTIVE: Recommended indications for exchange transfusions (ET) according to cord blood bilirubin concentrations vary between 4.5 and 7.0 [mg/dl]. There is no proof that cord blood bilirubin is able to predict the postnatal course of bilirubin concentrations. Only a few data are available on fetal bilirubin metabolism and postnatal bilirubin dynamics in the hemolytic disease of the newborn.

New Recommendations Not Very Different from Current Practice

To the Editor.— After reading the article by Newman and Maisels1 regarding evaluation and treatment of the jaundiced term newborn, I fail to see why their recommendations are substantially different from current practice. They merely point out what everyone has known (and not known) for a long time: 1. The magnitude of blood bilirubin concentration is not a particularly good predictor of bilirubin toxicity except in specific clinical settings such as hemolysis; ie, the total bilirubin concentration is neither a sensitive or specific indicator of the likelihood of bilirubin toxicity in the well, term jaundiced newborn.

Bile pigment formation and excretion in the rabbit

1. 1. Bile and plasma levels of biliverdin and bilirubin, together with the hepatic biliverdin reductase and bilirubin UDP-glucuronosyl transferase activities, were studied in the rabbit. 2. 2. No biliverdin could be detected in the blood plasma. The bilirubin concentration in blood was 7.81 ± 0.79 μmol/1. 3. 3. Biliverdin was the predominant pigment in bile (63%). 4. 4. Hepatic biliverdin reductase activity was 0.086 ±0.016 nmol/mg protein/hr. The synthesis of bilirubin was apparently limited by the enzyme activity. 5. 5. Most of the bilirubin in bile was conjugated (90%) with monoconjugates predominating (75%). 6. 6. Hepatic UDP-glucuronosyl transferase activity was 2.65 ± 0.18 and 1.14 ± 0.16 μmol/mg protein/hr with and without activation, respectively.

Effect of sodium benzoate on the cutaneous bilirubin content of the adult Gunn rat.

Na benzoate, which dissociates intravascular bilirubin-albumin complexes, might thus have the potential for driving bilirubin from the plasma into tissues such as the skin. We investigated this hypothesis in the adult Gunn rat. As others, we observed an early fall in blood bilirubin concentration after intraperitoneal Na benzoate injection, without any change in skin bilirubin content. Nevertheless, we observed a significant decrease (p less than 0.01) in skin bilirubin content at 24 and then 48 h after Na benzoate injection, at which times blood bilirubin remained at a low level. The phenomenon was reversible since, at 8 days after Na benzoate injection, blood and skin bilirubin contents had returned to control values. Regarding the decrease in skin bilirubin content after Na benzoate injection we described a dose-effect relationship. So, we could not confirm our hypothesis. We concluded that the phenomenon we observed is probably due to a shift in the distribution equilibrium of the pigment between serum, skin and other tissues.

Rapid Fluorometric Assay of Bilirubin and Bilirubin Binding Capacity in Blood of Jaundiced Neonates: Comparisons with Other Methods

The concentrations of total blood bilirubin, albumin-bound bilirubin, and the reserve and total bilirubin binding capacities of 35 neonatal blood samples (28 patients) were determined by automated front-face fluorometry ((hematofluorometer). These values were compared to results of diazo determinations, Sephadex gel filtration, and peroxidase-oxidation methods. Total blood bilirubin level by fluorometry agreed well with the total plasma bilirubin level by diazotization (r = .96, sigma = 1.7 mg/100 ml). Albumin-bound bilirubin concentrations by fluorometry also correlated well with diazo values (r = .95, sigma = 1.9 mg/100 ml) and were slightly lower than the total blood bilirubin concentrations. Values for total bilirubin binding capacity determined by fluorometry agreed well with results obtained for the same specimens by Sephadex gel filtration (n = 28, r = .97, sigma = 1.8 mg/100 ml) and by peroxidase-catalyzed oxidation (n = 25, r = .97, sigma = 1.7 mg/100 ml). The agreement among the results obtained by the three methods indicates a well-defined in vitro end point at which available primary or "tight" binding sites on albumin are saturated with bilirubin. In this clinical experience the coefficient of variation of results with the hematofluorometer was 8.4% for total blood bilirubin and 6.5% for total binding capacity. A comparison of "sick" with "well" infants revealed that the fraction of bilirubin not bound to albumin was significantly different for these two groups. The assays made with the hematofluorometer are quick (10 to 15 minutes) and require only a small quantity (approximately 150 microliters) of blood.

A Rapid Fluorometric Method for Determining Bilirubin Levels and Binding in the Blood of Neonates: Comparisons with a Diazo Method and with 2-(4'-Hydroxybenzene)azobenzoic Acid Dye Binding

A simple, rapid fluorometric method for determining the albumin-bound bilirubin concentration, total blood bilirubin concentration, and the bilirubin reserve-binding capacity of albumin was clinically evaluated using blood specimens from 79 neonates. This study showed that these bilirubin determinations, made by means of the Bell Laboratories hematofluorometer, correlated well with plasma bilirubin levels obtained by a diazotization (Jendrassik-Grof) method. Hematofluorometer reserve-binding capacities correlated very well with 2-(4'-hydroxybenzene)azobenzoic acid (HABA) dye reserve-binding capacities for specimens of artificially jaundiced adult blood. For specimens of neonatal blood the HABA dye reserve capacity was, on the average, higher than the hematofluorometer reserve-binding capacity, particularly for specimens from low-birth-weight babies (less than 2,000 gm). Comparison of HABA reserve capacity and hematofluorometer reserve capacity for high-birth-weight babies (greater than 2,000 gm) gave data very similar to those for adult blood specimens. The specific bilirubin-binding capacity of albumin was found to be greater for infants whose birth weight exceeded 2,000 gm than for the lower birth weight group. The total blood bilirubin concentration obtained by the hematofluorometer is shown to be significantly higher than the concentration of bilirubin bound to albumin, an indication of other important compartments of bilirubin in blood.

Value of measuring cord blood bilirubin concentration in ABO incompatibility.

Value of measuring cord blood bilirubin concentration in ABO incompatibility.

Influence of Intravenous Nutrients on Bilirubin Transport. III. Emulsified Fat Infusion

Infusions and injections of Intralipid were administered to congenitally jaundiced rats (Gunn) in whom the total body bilirubin pool was uniformly labeled with radioactive bilirubin. These isotopic studies indicated that Intralipid treatment had no effect on the kinetics of bilirubin formation, transport, tissue distribution, and clearance. There were no significant differences between control and fat emulsion-treated animals in the total bilirubin pool, plasma bilirubin pool, biologic half-life of bilirubin, fractional turnover, and exponential decline in plasma bilirubin specific activity at steady state. Bilirubin concentrations in blood, plasma, liver, kidneys, brain, adipose tissue, and muscle were unaltered during the course of continuous infusions (up to 24 hr) of Intralipid. These results indicate that Intralipid administered in clinically applicable doses and regimens has no discernible effects on bilirubin metabolism in jaundiced rats.