Noninvasive measurement of total serum bilirubin in a multiracial predischarge newborn population to assess the risk of severe hyperbilirubinemia

Transcutaneous bilirubin measurements and serum total bilirubin levels in indigenous African infants

OBJECTIVE

The objective of this study was to determine whether transcutaneous bilirubin (TcB) measurements correlate with serum total bilirubin (STB) levels in indigenous, darkly pigmented African newborns with varying degrees of skin pigmentation, some of which had developed kernicterus.

METHODS

Jaundiced infants who were < or =2 weeks of age and admitted to Baptist Medical Center-Eku (Eku; n = 29) and Jos University Teaching Hospital (Jos; n = 98) in Nigeria were studied. TcB measurements using the BiliChek were made simultaneously with blood sampling for STB measurements by spectrophotometry before phototherapy.

RESULTS

Using linear regression analysis, we found that measurements of TcB correlated well with those of STB with r values of.90 and.88 for Eku and Jos, respectively. Mean bias and imprecision of TcB measurements as compared with STB measurements for the total population was 0.5 +/- 7.6 mg/dL using the method of Bland and Altman. At STB > or 12 mg/dL, correlation (r =.84) and bias and imprecision (-1.2 +/- 8.6 mg/dL) of measurements were only slightly poorer. Furthermore, when infants were grouped by degree of skin pigmentation, correlations of TcB and STB measurements remained strong.

CONCLUSIONS

From these results, we can conclude that TcB measurements are a useful and reliable index for estimating STB levels in pigmented neonates, including those with hyperbilirubinemia and kernicterus. In the absence of reliable STB measurements, the relatively simple and noninvasive TcB measurements can be an important adjunct in directing phototherapy and exchange transfusions, thereby preventing bilirubin-induced morbidity and mortality in low-technology clinical environments.

Evaluation of a new transcutaneous bilirubinometer

OBJECTIVE

The objective of this study was to evaluate the Minolta/Hill-Rom Air-Shields Transcutaneous Jaundice Meter model JM-103.

METHODS

We studied a convenience sample of 849 newborns > or =35 weeks of gestation in 3 hospitals. These infants had total serum bilirubin (TSB) levels measured on clinical indication, and transcutaneous bilirubin (TcB) levels were obtained within 1 hour of the TSB levels. The population was 59.2% white, 29.8% black, 4.5% East Asian, 3.8% Middle Eastern, 1.6% Indian/Pakistani, and 1.1% Hispanic.

RESULTS

There was a close correlation between TSB and TcB values in all of the population groups: white (n = 503, r =.949); black (n = 253, r =.822); and East Asian, Indian/Pakistani, and Hispanic (n = 93, r =.926). In the black population, the correlation was less close than in the other groups, and differences between the TcB and TSB measurements tended to increase with rising TSB values. JM-103 values differed from TSB values by 3 mg/dL or more in 2% of white, 3.2% of other, and 17.4% of black infants. In these black infants, the JM-103 value was always greater than the TSB value.

CONCLUSIONS

We conclude that TcB measurements using the JM-103 jaundice meter correlate very closely with TSB levels over the range of TSB encountered in this study. Because only 3.3% of our infants had TSB values >15 mg/dL (257 micro mol/L), more data are needed in this range of TSB concentration. The correlation in black infants is not as close as in other groups, but because the tendency in blacks is for the JM-103 to overestimate serum bilirubin levels, dangerous clinical errors are unlikely to occur. The measurement technique is rapid and simple, and it is easy to perform repeated measurements over time, thus reducing the likelihood of error. TcB measurements with the JM-103 jaundice meter should obviate the need for most serum bilirubin levels in newborn infants > or =35 weeks of gestation, although serum bilirubin measurements are still required when treatment with phototherapy or exchange transfusion is being considered.

Newborn jaundice and kernicterus--health and societal perspectives

Kernicterus, a preventable injury to the brain from severe neonatal jaundice, has re-emerged in the United States as a public and societal health concern. Kernicterus, in its usually recognized form, causes devastating disabilities, including athetoid cerebral palsy and speech and hearing impairment. This condition not only ranks amongst the highest cost per new case (per CDCs Financial Burden of Disability study, 1992), but also results in profound and uncompromising grief for the family and loss to siblings of healthy, talkative playmates. And for the child with kernicterus (usually remarkably intelligent, but trapped in an uncontrollable body), grief and frustration are enormous. In 2001 national healthcare organizations, including Centers for Disease Control (CDC), the Joint Commission for the Accreditation of Healthcare Organizations (JACHO) and the American Academy of Pediatrics (AAP) issued alerts to all accredited hospitals and public health professionals in the United States that all healthy infants are at potential risk of kernicterus if their newborn jaundice is unmonitored and inadequately treated. The re-emergence of kernicterus in the United States is the result of interacting phenomena including (a) Early hospital discharge (before extent of jaundice is known and signs of impending brain damage have appeared); (b) Lack of adequate concern for the risks of severe jaundice in healthy term and near newborns; (c) An increase in breast feeding; (d) Medical care cost constraints; (e) Paucity of educational materials to enable parents to participate in safeguarding their newborns; and (f) Limitations within in healthcare systems to monitor the outpatient progression of jaundice. A multidisciplinary approach that encompasses both healthcare and societal needs should be evaluated at a national level for practical and easy to implement strategies. An approach that is based on principles of evidence-based medicine, patient-safety and family centeredness is presented in this article. These strategies should also be based on public awareness campaign such that the healthcare providers can attempt to achieve a "Zero Tolerance of Kernicterus" and thereby decrease both childhood disabilities and infant mortality within the community.

Hemolysis and hyperbilirubinemia in an African American neonate heterozygous for glucose-6-phosphate dehydrogenase deficiency

Despite recent case reports of bilirubin encephalopathy in African American glucose-6-phosphate dehydrogenase (G6PD)-deficient neonates, there is a misconception that, in African Americans, G6PD deficiency need not be considered in the differential diagnosis of hyperbilirubinemia. We present a case of a hyperbilirubinemic African American female neonate in whom coexisting G6PD deficiency in the heterozygous state, and Gilbert's syndrome, were confirmed by DNA analysis. Hemolysis, predictive of the subsequent icterus, was documented by end-tidal carbon monoxide determinations at two time periods within the first 25 hours of life. A diagnosis of G6PD deficiency should be considered in African American neonates, females as well as males, with unexplained hemolysis or hyperbilirubinemia.

A comparison of transcutaneous bilirubinometers: SpectRx BiliCheck versus Minolta AirShields

BACKGROUND

Two devices are available for making transcutaneous estimates of serum bilirubin (SBR): the Minolta AirShields JM102 and the new SpectRx BiliCheck.

OBJECTIVES

(a) To measure how well the readings produced by these devices agree with SBR measured in the laboratory; (b) to estimate for each device, the proportion of infants with clinical jaundice who would require blood sampling if the device was used as a screening tool to detect infants with SBR > or = 250 micromol/l.

DESIGN

Prospective cohort study of jaundiced infants who required SBR at < or = 20 days of postnatal age. Those who had received phototherapy or exchange transfusion were excluded.

SETTING

Tertiary neonatal service in South-East Scotland.

INTERVENTIONS

Within 30 minutes of SBR sampling, transcutaneous bilirubinometry was performed using one Minolta and two SpectRx devices (designated A and B).

RESULTS

Sixty-four neonates were enrolled, 19 of which were preterm (31-35 weeks). The 95% confidence intervals of a device reading corresponding to SBR were +/- 66.7, +/- 67.9, and +/- 66.4 micromol/l respectively. Using the devices to identify all SBR > or = 250 micromol/l would reduce SBR sampling by 23%, 16%, and 20% respectively.

CONCLUSIONS

Given that SBR levels range from 50 to 400 micromol/l in jaundiced infants, the 95% confidence intervals of the devices are wide at +/- 67 micromol/l. The SpectRx can be used as a screening tool for hyperbilirubinaemia but there is no advantage in using it over the Minolta.

Assessment of a transcutaneous device in the evaluation of neonatal hyperbilirubinemia in a primarily Hispanic population

OBJECTIVE

To compare estimates of serum bilirubin as determined by a transcutaneous device (BiliChek [BC]) with laboratory-measured total serum bilirubin (TSB) in a predominately Hispanic population in which a significant number of TSB values > or =15 mg/dL was anticipated.

METHODS

A total of 248 Hispanic and 56 non-Hispanic neonates were studied. Transcutaneous measurements were performed by 1 investigator within 30 minutes of blood sampling for TSB; TSB was determined in a large clinical laboratory using the diazo Jendrassik-Grof with blank method. Agreement between BC and TSB determinations was assessed using Bland-Altman plots and the Bradley-Blackwood test. Interdevice comparisons were made among the BC devices. Predictive indices for TSB >10 mg/dL and >15 mg/dL were determined using various BC cutoff values.

RESULTS

TSB was > or =15 mg/dL in 31% of the Hispanic neonates. BC generally tended to underestimate TSB determinations, and this trend was more pronounced when TSB was >10 mg/dL. Very high sensitivities were observed only when relatively low BC cutoff values were used to predict TSB >10 mg/dL or >15 mg/L. Relatively small numbers of infants had BC values in these low ranges.

CONCLUSIONS

The tendency of BC to underestimate TSB limits its usefulness in neonates with relatively high TSB. In this population, most infants would have required additional evaluation to ensure that TSB was not >10 mg/dL or >15 mg/dL. It seems that the discrepancy between this study and previous studies of BC is related to our relatively large number of TSB values > or =15 mg/dL.

Evaluation of the direct antiglobulin (Coombs') test for identifying newborns at risk for hemolysis as determined by end-tidal carbon monoxide concentration (ETCOc); and comparison of the Coombs' test with ETCOc for detecting significant jaundice

OBJECTIVE

First, to determine the sensitivity, specificity, and positive predictive value (PPV) of the direct antiglobulin test (DAT) for significant hemolysis in the neonate, as referenced to end-tidal carbon monoxide, the criterion standard for estimating the rate of hemolysis; and second, to evaluate the predictive value of the two procedures for significant jaundice.

DESIGN

Consecutive term newborns admitted to the nursery of an inner-city university hospital over a 15-week period. DAT screening by the Blood Bank was performed on all. End-tidal carbon monoxide levels were obtained at 12+/-6 and at 24+/-6 hours of age. Infants of nonsmoking mothers whose 12-hour exhaled carbon monoxide level was > or = 95th percentile were defined as having significant hemolysis.

RESULTS

n=660; DAT was positive in 23 (3.5%). Using the 12-hour end-tidal carbon monoxide > or = 3.2 microl/l (> or = 95th percentile) as reference (n=499 nonsmokers), the sensitivity of the DAT was 38.5% (10 of 26) and specificity 98.5% (466 of 473) for the detection of significant hemolysis. The PPV of the DAT for significant hemolysis at 12 hours was 58.8% (10 of 17). For significant jaundice the PPV of end-tidal carbon monoxide was greater than that for DAT (65.4% vs 52.9%), although not statistically so (p=0.25). The negative predictive values were similar.

CONCLUSION

DAT fails to identify over half of the cases of significant hemolysis that are diagnosed by end-tidal carbon monoxide. A neonate with a positive DAT has about a 59% chance of having significant hemolysis. End-tidal carbon monoxide may also provide a more sensitive index for predicting significant jaundice.

Isoimmunization is unlikely to be the cause of hemolysis in ABO-incompatible but direct antiglobulin test-negative neonates

OBJECTIVE

It is stated that the direct antiglobulin (Coombs') test (DAT) may be negative in ABO hemolytic disease of the newborn. Thus, significant jaundice in neonates who are A-B incompatible with their mothers but DAT test negative is often attributed to isoimmunization and another diagnosis is not sought. We wished to determine the rate of bilirubin production, as an objective measure of hemolysis, in 2 groups of DAT-negative neonates--ABO-compatible and ABO-incompatible--and in DAT-positive ABO-incompatible neonates.

METHODS

In consecutive, term, healthy newborns who were admitted to the general care nursery, we measured the level in parts per million (ppm) of end-tidal breath carbon monoxide (CO), corrected for inspired CO (ETCOc), an index of the rate of bilirubin production. We compared the levels in DAT-negative ABO-incompatible neonates with those in ABO-compatible neonates and with the levels in DAT-positive ABO-incompatible neonates. Statistical analysis was performed using 2-sample t and chi(2) tests.

RESULTS

There was no significant difference between the mean 12-hour ETCOc levels in DAT-negative ABO-incompatible neonates (n = 60, 2.2 +/- 0.6 ppm) versus DAT-negative ABO-compatible neonates (n = 171, 2.1 +/- 0.6 ppm), although there was a difference between the mean levels in DAT-positive ABO-incompatible neonates (n = 14, 3.4 +/- 1.8 ppm) and the DAT-negative groups. Four DAT-negative ABO-incompatible neonates had elevated ETCOc levels; in 2, we diagnosed a specific hematologic abnormality, namely, glucose-6-phosphate dehydrogenase deficiency in 1 and elliptocytosis in the other.

CONCLUSION

In DAT-negative newborns with significant jaundice or increased bilirubin production, even if ABO-incompatible, a cause other than isoimmunization should be sought.

Non-invasive bilirubinometry in neonatal jaundice

This chapter will focus on techniques that have been developed to measure transcutaneous bilirubin (TcB). The first electronic TcB device proved to be useful when used as a screening method for identifying newborns who needed a serum bilirubin determination. Newer TcB devices can be used not only as screening tools but also as reliable substitutes for serum bilirubin measurements. The Chromatics Colormate III is still based on the colour of the skin, estimating serum bilirubin from skin-reflectance (skin colour) whereas the BiliCheck measures transcutaneous bilirubin by utilizing the entire spectrum of visible light (380 to 760 nm) reflected by the skin.

Kernicterus: an international perspective

Kernicterus occurs in all parts of the world. The risk is increased in countries where glucose-6-phosphate dehydrogenase-deficiency is common. In the 1990's more case reports of infants who developed kernicterus were published than in the previous decades. A combination of reduced concern for jaundice in newborns, early discharge with inadequate follow-up and a decreased awareness of the signs that may herald serious toxicity may have contributed to the apparent increase in the incidence of kernicterus. Although most jaundiced newborns do not need aggressive evaluation or treatment, physicians who deal with such infants still need to be vigilant. We lack the necessary tools to distinguish infants who may be particularly vulnerable to the effects of bilirubin on the brain from those who may tolerate high serum bilirubin levels without harm. Therefore it is imperative that each infant with significant jaundice be conscientiously evaluated and a plan for testing and, if necessary, therapy be formulated. Transcutaneous measurement of bilirubin is a simple tool that significantly reduces the need for invasive tests. Signs of possible neurotoxicity must never be disregarded or neglected. Any jaundiced infant who shows signs of possible neurotoxicity should receive intensive phototherapy as an emergency procedure while further evaluation continues. Further studies regarding bilirubin toxicity and neonatal jaundice are needed, both in the basic science as well as in the clinical arena.

Improved transcutaneous bilirubinometry: comparison of SpectR(X) BiliCheck and Minolta Jaundice Meter JM-102 for estimating total serum bilirubin in a normal newborn population

OBJECTIVE

To compare a new transcutaneous bilirubinometer, which uses multiple wavelength analysis of reflectance data (BiliCheck system), and the commonly used two-wavelength bilirubinometer (Jaundice Meter JM-102) to estimate serum bilirubin.

STUDY DESIGN

Jaundiced newborn term infants (101 babies) had transcutaneous bilirubinometry (TCB) using each bilirubinometer, a determination of skin color using a skin color chart, and a total serum bilirubin determination.

RESULTS

The variability of the BiliCheck system was less than the variability of the Jaundice Meter JM-102. The accuracy of the BiliCheck system was not affected by skin color, whereas the Jaundice Meter JM-102 was affected.

CONCLUSION

Multiple wavelength analysis, as used in the BiliCheck system, is a significant improvement in TCB.

Criteria for treatment of neonatal jaundice

Treatment of neonatal hyperbilirubinemia is usually based on the measurements of total serum bilirubin levels. Based on empirical data, it is generally recommended to start phototherapy at lower levels in low birth weight and very low birth weight infants than in term infants, but no general agreement exists on exact limits. Treatment criteria in preterm infants do not, however, have the same empirical backing as in term infants. The very low and extremely low birth weight infants are more susceptible to bilirubin toxicity. However, bilirubin may function as an antioxidant and enzyme inducer in these infants. Several other different approaches to establish treatment criteria have also been suggested, and a summary of these are presented and discussed. With the exception of measurement of unbound bilirubin, very few of these approaches have been validated in routine clinical settings. However, unbound bilirubin is at present mainly used also as a parameter to be evaluated in relation to total bilirubin values. The present treatment criteria result in a considerable overtreatment particularly of term infants. However, with a more relaxed attitude toward neonatal hyperbilirubinemia by health care professionals, kernicterus is again reported in term infants. Because the basic mechanisms of bilirubin toxicity as well as the relative significance of the maximum serum bilirubin level compared to the duration of hyperbilirubinemia are not known, individual assessment of a newborn infant's tolerance for hyperbilirubinemia is difficult. Major changes in the empirically developed criteria for treatment of hyperbilirubinemia in the newborn are therefore not justified in the near future. For term infants, the search for validated criteria for follow-up of jaundiced infants after discharge are therefore more important than revision of existing criteria for phototherapy.