Abnormal endogenous carbon monoxide production in children with ineffective erythropoiesis

Carbon monoxide breath test assessment of mild hemolysis in Gilbert's syndrome

BACKGROUND

Mild hemolysis is difficult to determinate by traditional methods, and its role in Gilbert's syndrome (GS) is unclear. The main aims were to inspect the erythrocyte (RBC) survival in GS by using Levitt's carbon monoxide (CO) breath test and to assess its contribution to unconjugated hyperbilirubinemia.

METHODS

Fifty subjects with GS and 1 with type-II Crigler-Najjar syndrome (CN2) received RBC lifespan measurement with Levitt's CO breath test. Mean RBC lifespan was compared with normal referral value. Correlations of serum total bilirubin (TB) with RBC lifespan, blood panel data, demographic factors, and uridine diphosphate glucuronosyltransferase (UGT1A1) mutation load were calculated by Spearman analysis. Susceptibility factors for mild hemolysis were analyzed by multivariate regression analysis.

RESULTS

The mean RBC lifespan of the GS subjects was significantly shorter than the normal reference value (95.4 ± 28.9 days vs 126 days; t = -7.504, P < .01), with 30.0% below the lower limit of the normal reference range (75 days). The RBC lifespan of the participant with CN2 was 82 days. Serum TB correlated positively with UGT1A1 mutation load (γ = 0.281, P = .048), hemoglobin (γ = .359, P = .010) and hematocrit (γ = 0.365, P = .010), but negatively with RBC lifespan (γ = -0.336, P = .017). No significant susceptibility factors for mild hemolysis were found.

CONCLUSIONS

The results indicate that mild hemolysis indeed, exists in a portion of patients with GS and might serve as an important contributor to unconjugated hyperbilirubinemia in addition to UGT1A1 polymorphism. Further studies on the mechanism and the potential risks in various medical treatments might be wanted.

Human erythrocyte lifespan measured by Levitt's CO breath test with newly developed automatic instrument

Existing standard techniques for erythrocyte (RBC) lifespan measurement, such as quantitation of labeling with isotopes or biotin, are cumbersome and time-consuming. Given that endogenous CO originates mainly from degraded RBCs, a team lead by Levitt developed a CO breath test to enable more efficient RBC lifespan estimation. The purpose of this study was to evaluate the reliability of Levitt's CO breath test method with our newly developed automatic instrument. RBC lifespan measurements conducted by Levitt's CO breath test method were conducted in 109 healthy subjects and 91 patients with chronic hemolytic anemia. In healthy subjects, the RBC lifespan was 126 ± 26 days, similar to values obtained with classical standard labeling methods. RBC lifespan did not differ significantly between males and females or between juveniles and adults, and did not correlate with age. To our knowledge, this datum represents an RBC lifespan average for the largest sample to date. In subjects with hemolytic anemia, RBC lifespan was 29 ± 14 days, which is significantly shorter than that of the healthy subjects (p = 0.001). Using 75 days as a cut-off, diagnostic accuracy for hemolytic anemia in the present study sample was 100%. In conclusion, the present results indicate that Levitt's CO breath test is an ideal method for human RBC lifespan measurement, and the newly developed automatic instrument is reliable and convenient for clinical practice.

Unusual early presentation of Gilbert syndrome in pediatric recipients of liver transplantation

BACKGROUND

Gilbert syndrome as a rule becomes manifest in adolescence or in early adulthood; it may be transferred by the donor to orthotopic liver transplant (OLT) recipients.

METHODS

We examined the frequency of Gilbert syndrome in 46 OLT pediatric recipients who had a follow-up of 1 year or more. Diagnostic criteria included unexplained chronic or recurrent unconjugated hyperbilirubinemia; its increase after reduced caloric intake plus prolonged fasting, without changes of the proportion of conjugated bilirubin; and high relative amounts of serum unconjugated bilirubin IXa and prevalence of the monoglucuronide over the diglucuronide.

RESULTS

Of the 46 patients, 42 had normal bilirubin values. Only four otherwise healthy OLT recipients showed hyperbilirubinemia and normal conjugated fractions. Liver donors had been four men. Hyperbilirubinemia persisted with a fluctuating pattern for the whole follow-up after OLT in all. Total bilirubin level in blood samples obtained after reduced caloric intake and prolonged fasting became notably higher than basal values, whereas the proportion of conjugated bilirubin remained stable. High relative amounts of unconjugated bilirubin IXa and prevalence of the monoglucuronide over the diglucuronide were found. Finally, DNA from liver donors' lymphocytes was available for one jaundiced and two nonjaundiced patients: tests for abnormalities in the promoter region of the gene for the enzyme bilirubin uridine diphospho-glucuronosyltransferase were in agreement with a diagnosis of GS in the former one,

CONCLUSIONS

Gilbert syndrome may have an unusual early presentation in pediatric OLT recipients.