Screening of newborn infants for cholestatic hepatobiliary disease with tandem mass spectrometry

Pre-admission consultation and late referral in infants with neonatal cholestasis

AIMS

To study factors leading to delayed referral in neonatal cholestasis at a tertiary centre in Malaysia.

METHODS

A prospective, observational study on consecutive infants with neonatal cholestasis referred to a tertiary unit paediatric liver unit in Malaysia.

RESULTS

Thirty-one of the 65 (43%) patients studied encountered delay or had an inappropriate action taken before referral. Factors leading to delayed referral, which adversely affected the outcome of biliary atresia (BA) and neonatal acute liver failure, were repeated reassurances by medical and paramedical staff (n = 17, 26%), failure of hospital services at the referring hospital (n = 7, 11%) and parental refusal for referral (n = 5, 8%). Only three (14%) of the 22 patients who developed liver failure had liver transplantation (LT). The 1-year survival rate with native liver for BA was 35%, while overall 1-year survival rate (native liver and LT) was 41%.

CONCLUSIONS

Repeated false reassurance, failure of hospital services and parental refusal all contributed to delayed referral in neonatal cholestasis. In addition to education of medical and public health workers, and parents on the importance of early referral in neonatal cholestasis, health authorities in Malaysia should consider the feasibility of universal stool colour screening in newborn infants to improve the outcome of BA.

Current management of biliary atresia

Extra-hepatic biliary atresia occurs in approximately 1:15,000 live births leading to about 50 new cases/year in the UK. Presentation is with prolonged jaundice, usually in a term baby who develops signs of obstructive jaundice. Management has been improved by public and professional education to encourage early referral and diagnosis to facilitate initial surgery before 8 weeks of age. Surgical management is complementary and includes an attempt to restore biliary flow (the Kasai portoenterostomy) and liver transplantation if necessary. Medical management consists of antibiotics, ursodeoxycholic acid to encourage bile flow, fat soluble vitamin supplementation and nutritional support. Centralising surgery to specialised centres has improved survival of this potentially fatal disease to over 90% in the UK. Over half of infants undergoing portoenterostomy will clear the jaundice and have a greater than 80% chance of a good quality of life, reaching adolescence without transplantation. For those children developing intractable complications of cirrhosis and portal hypertension, liver transplantation provides a 90% chance of achieving normal life.

Screening and outcomes in biliary atresia: summary of a National Institutes of Health workshop

Biliary atresia is the most common cause of end-stage liver disease in the infant and is the leading pediatric indication for liver transplantation in the United States. Earlier diagnosis (<30-45 days of life) is associated with improved outcomes following the Kasai portoenterostomy and longer survival with the native liver. However, establishing this diagnosis is problematic because of its rarity, the much more common indirect hyperbilirubinemia that occurs in the newborn period, and the schedule for routine infant health care visits in the United States. The pathogenesis of biliary atresia appears to involve immune-mediated fibro-obliteration of the extrahepatic and intrahepatic biliary tree in most patients and defective morphogenesis of the biliary system in the remainder. The determinants of the outcome of portoenterostomy include the age at surgery, the center's experience, the presence of associated congenital anomalies, and the postoperative occurrence of cholangitis. A number of screening strategies in infants have been studied. The most promising are early measurements of serum conjugated bilirubin and a stool color card given to new parents that alerts them and their primary care provider to alcholic stools. This report summarizes a National Institutes of Health workshop held on September 12 and 13, 2006, in Bethesda, MD, that addressed the issues of outcomes, screening, and pathogenesis of biliary atresia.

Screening for biliary atresia by infant stool color card in Taiwan

OBJECTIVE

We aimed to detect biliary atresia (BA) in early infancy to prevent additional liver damage because of the delay of referral and surgical treatment and to investigate the incidence rate of BA in Taiwan.

METHODS

A pilot study to screen the stool color in infants for the early diagnosis of BA was undertaken from March 2002 to December 2003. We had designed an "infant stool color card" with 7 numbers of different color pictures and attached it to the child health booklet. Parents were then asked to observe their infant's stool color by using this card. The medical staff would check the number that the parents chose according to their infant's stool color at 1 month of age during the health checkup and then send the card back to the stool color card registry center.

RESULTS

The average return rate was approximately 65.2% (78,184 infants). A total of 29 infants were diagnosed as having BA, and 26 were screened out by stool color card before 60 days of age. The sensitivity, specificity, and positive predictive value were 89.7%, 99.9%, and 28.6%, respectively. Seventeen (58.6%) infants with BA received a Kasai operation within 60-day age period. The estimated incidence of BA in screened newborns was 3.7 of 10,000.

CONCLUSIONS

The stool color card was a simple, efficient, and applicable mass screening method for early diagnosis and management of BA. The program can also help in estimating the incidence and creating a registry of these patients.

Contemporary clinical usage of LC/MS: analysis of biologically important carboxylic acids

OBJECTIVES

This review summarizes the current role of LC/MS in the diagnosis and screening of clinical conditions involving the analysis of biologically important carboxylic acids.

DESIGN AND METHODS

Carboxylic acids are divided into six logical categories of acid size and function. Details of chromatographic separation methods and modes of mass spectrometer operation are described for each category.

RESULTS

The use of LC/MS in clinical applications such as the diagnosis of inherited and acquired metabolic disorders, gastrointestinal disorders, cancer and diabetes and therapeutic drug monitoring is discussed.

CONCLUSIONS

The mild conditions, speed and sensitivity advantages of LC/MS analysis, over alternatives, are highlighted. The sensitivity and specificity afforded by the combination of tertiary and quaternary ammonium derivatives and tandem mass spectrometry for the analysis of carboxylic acids is emphasized. Potential for a greater range of LC/MS carboxylic analyses, including stereoisomeric intermediates, is predicted.

Guideline for the evaluation of cholestatic jaundice in infants: recommendations of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition

For the primary care provider, cholestatic jaundice in infancy, defined as jaundice caused by an elevated conjugated bilirubin, is an uncommon but potentially serious problem that indicates hepatobiliary dysfunction. Early detection of cholestatic jaundice by the primary care physician and timely, accurate diagnosis by the pediatric gastroenterologist are important for successful treatment and a favorable prognosis. The Cholestasis Guideline Committee of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition has formulated a clinical practice guideline for the diagnostic evaluation of cholestatic jaundice in the infant. The Cholestasis Guideline Committee, consisting of a primary care pediatrician, a clinical epidemiologist (who also practices primary care pediatrics), and five pediatric gastroenterologists, based its recommendations on a comprehensive and systematic review of the medical literature integrated with expert opinion. Consensus was achieved through the Nominal Group Technique, a structured quantitative method. The Committee examined the value of diagnostic tests commonly used for the evaluation of cholestatic jaundice and how those interventions can be applied to clinical situations in the infant. The guideline provides recommendations for management by the primary care provider, indications for consultation by a pediatric gastroenterologist, and recommendations for management by the pediatric gastroenterologist. The Cholestasis Guideline Committee recommends that any infant noted to be jaundiced at 2 weeks of age be evaluated for cholestasis with measurement of total and direct serum bilirubin. However, breast-fed infants who can be reliably monitored and who have an otherwise normal history (no dark urine or light stools) and physical examination may be asked to return at 3 weeks of age and, if jaundice persists, have measurement of total and direct serum bilirubin at that time. This document represents the official recommendations of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition on the evaluation of cholestatic jaundice in infants. The American Academy of Pediatrics has also endorsed these recommendations. These recommendations are a general guideline and are not intended as a substitute for clinical judgment or as a protocol for the care of all patients with this problem.

Population screening for neonatal liver disease: potential for a community-based programme

OBJECTIVES

To evaluate a community-based screening programme for detecting neonatal liver disease by the quantitation of conjugated bilirubin in blood.

SETTINGS AND METHODS

Prospective cohort/observational study using spare plasma from routinely collected liquid neonatal screening specimens from babies born in Birmingham over a two-year period. Babies with a conjugated bilirubin above 18 mumol/l and comprising more than 20% of the total bilirubin were followed up. A total of 27654 neonates were tested in the community, with a further 2425 samples from babies hospitalised at the time of the test.

RESULTS

In the community-based series, 84.7% of the specimens received were analysed, the remainder being unusable mainly because of gross haemolysis (8.6%) or insufficient sample (5.8%). In 107 neonates the results were above the cut-off limits (0.46% of the number analysed). Of these, 12 had persistently abnormal results, 11 of whom had confirmed liver disease. The liver diseases detected included neonatal hepatitis (n=6), extra-hepatic biliary atresia (n=2), hypopituitarism (n=1), alpha-1-antitrypsin deficiency (n=1) and Alagille syndrome (n=1). The sensitivity and specificity of the test for babies in the community were 100% and 99.6%, respectively.

CONCLUSIONS

Conjugated bilirubin in plasma measured at 6-10 days is a reliable marker for neonatal liver disease, and a population screening programme based on this method has the potential to improve the survival and quality of life of infants born with liver disease. However, testing as part of the neonatal screening programme will prove practical only if the method can be adapted to use dried blood spots.

Biliary atresia

Biliary atresia (BA) is a congenital obliterative cholangiopathy of unknown aetiology, affecting both the intra- and extrahepatic bile ducts. Although relatively rare, BA must be excluded in any infant with conjugated hyperbilirubinaemia since the prognosis is improved by early diagnosis and prompt surgery. At least two phenotypes of BA are currently recognized; the syndromic variety is associated with other congenital anomalies and a poorer outcome. The results of treatment have steadily improved and, with a combination of timely expert surgery (Kasai portoenterostomy) and liver transplantation in specialist centres, good quality long-term survival is now possible in more than 90% of affected patients. A better understanding of the aetiology of BA and the pathogenesis of hepatic fibrosis is needed in order to develop new therapeutic strategies.

Advances in analytical mass spectrometry to improve screening for inherited metabolic diseases

Gas chromatography/mass spectrometry became available more than 30 years ago and has subsequently profoundly contributed not only in the identification of a wide range of inborn errors but also as a key tool for clinical diagnostic screening of genetic metabolic disease. Due to extraordinary advances in liquid chromatography and mass spectrometry (MS) developed in the last decade, the utilisation of MS and the potential number of applications for the purpose of metabolic screening is currently undergoing considerable expansion.

CONCLUSIONS

This overview aims to describe only current new developments in clinically most relevant applications, in particular with focus on low molecular weight compounds.

The spectrum of surgical jaundice in infancy

BACKGROUND

Conjugated jaundice arising during infancy may be caused by a number of different surgical conditions. The aim of this study was to compare clinical features, management, and outcome of all types of surgical jaundice presenting in the first year of life.

METHODS

A retrospective review was conducted of all infants born in the United Kingdom with jaundice caused by a surgical cause referred to the authors' institution from January 1992 to December 1999.

RESULTS

There were 171 infants who could be separated into 3 specific groups: biliary atresia (BA, n = 137), inspissated bile syndrome (IBS; n = 14), and choledochal malformation (CM; n = 12) together with a group containing various miscellaneous conditions (n = 8). Infants with BA had higher bilirubin (P <.01) and aspartate aminotransferase levels (P <.001) and came to surgery earlier (P <.01) than infants with either IBS or CM. Infants with IBS and CM were more likely to be premature and have other malformations, respectively. Ultrasound scan was the principal investigation in the differentiation of BA from other causes of jaundice. Accurate prelaparotomy diagnosis was made by percutaneous liver biopsy in 87% of cases later shown to be BA. Currently, 88 (64%) of children with BA are alive with their native liver postportoenterostomy, 4 have died, and 45 have undergone liver transplantation (with 1 death postoperatively). A policy of primary portoenterostomy for BA followed by transplantation, if necessary, resulted in a survival rate of over 95%. All children in the other diagnostic groups are alive and anicteric after appropriate surgical intervention.

CONCLUSIONS

Approximately 80% of infants presenting with surgical jaundice have biliary atresia, whereas those with inspissated bile syndrome and choledochal malformations make up most of the remainder. Mortality in this age-group is confined to infants with BA, but even on these infants an overall survival rate of greater than 95% is currently expected.

Tandem mass spectrometry in the study of fatty acids, bile acids, and steroids

Over the last 50 years, the mass spectrometry of lipids has evolved to become one of the most mature techniques in biomolecule analysis. Many volatile and non-polar lipids are directly amenable to analysis by gas-chromatography-mass spectrometry (GC-MS), a technique that combines the unsurpassed separation properties of gas-chromatography with the sensitivity and selectivity of electron ionization mass spectrometry. Less volatile and/or thermally labile lipids can be analyzed by GC-MS, following appropriate sample derivatization. However, many complex lipids are not readily analyzed by GC-MS, and it is these molecules that are the subject of the current review. Since the early 1970s, there have been three outstanding developments in mass spectrometry that are particularly appropriate in lipid analysis; i.e., the introduction of (i) fast atom bombardment (FAB); (ii) electrospray (ES); and (iii) tandem mass spectrometry (MS/MS). The FAB and ES ionization techniques will be discussed in relation to MS/MS, and examples of their application in biochemical studies will be presented. The review will concentrate on the analysis of fatty acids, bile acids, steroid conjugates, and neutral steroids.

Bile acid stress in the mother and baby unit

Intrahepatic cholestasis of pregnancy (ICP) affects about 0.7% of deliveries in Britain. It is regarded as a benign condition for the mother but is associated with increased fetal mortality in late pregnancy and early delivery is advised. Ursodeoxycholic acid (UDCA) treatment is beneficial to the mother and does not appear to harm the fetus. ICP is often regarded as a disease of the maternal liver already made 'cholestatic' by high levels of circulating progesterone. We propose that ICP should be considered as a feto-maternal disease involving complex interactions between maternal and fetal bile acid metabolism across the placenta. During the late stages of gestation, when there is a rise in fetal and maternal bile acid levels, the placenta may fail to render potentially hepatotoxic bile acids water soluble and hence excretable. This might cause a vicious cycle leading to further cholestasis in the maternal liver already challenged by progesterone.

Quantitative Analysis of Bile Acids in Human Plasma by Liquid Chromatography-Electrospray Tandem Mass Spectrometry: A Simple and Rapid One-Step Method

Bile acids play a pivotal role in the metabolism of cholesterol and lipids. Their blood concentrations are important prognostic and diagnostic indicators of hepatobiliary and intestinal dysfunction. This class of molecules comprises a heterogeneous group of compounds with a common cholesterol scaffold. Recently, the introduction of liquid chromatography coupled to tandem mass spectrometry methods has revealed an innovative path in the quantisation of specific bile acids in biological specimens. A robust and sensitive method has been developed based on high performance liquid chromatography separation coupled to an electrospray triple-quadrupole mass spectrometer. Human plasma samples were analysed on a C18 reverse-phase column. The elution profiles were monitored in multiple reaction-monitoring mode, quantifying and identifying each analyte by its own unique precursor to product patterns. A linear correlation over a broad range of bile acid concentrations (0.1-100 microM) was observed. The average recovery period for all of the analysed bile acids was 98 +/- 3%. Intra-day and inter-day precision averages were 2% and 5.4%, respectively. The determination was achieved within a single chromatographic run for all unconjugated, glycine- and taurine-conjugated isomeric forms of bile acids. As a proof of principle this method has been validated on a small subset of cholestatic patients (n = 7) and compared to appropriate clinical controls (n = 10). Based upon our encouraging experimental results, the described HPLC separation coupled to tandem mass spectrometry method for the analysis of bile acids in biological samples is deemed a robust and accurate procedure. Consequently, we propose this technique as a suitable candidate method for the identification and quantitation of bile acids in routine analysis.

Validation of an ESI-MS/MS screening method for acylcarnitine profiling in urine specimens of neonates, children, adolescents and adults

BACKGROUND

Acylcarnitine (AC) profiling in dried blood spots by means of electrospray ionisation tandem mass spectrometry (ESI-MS/MS) has proven to be a useful method in neonatal screening, able to detect inborn errors of fatty acid oxidation, amino acid, organic acid and carnitine metabolism. Furthermore, this method is becoming increasingly applied in selective screening and in prenatal and postmortal diagnostics of inborn metabolic disorders, where urine is commonly used as specimen of interest. We therefore developed and validated a butylation method of acylcarnitine profiling in urine by ESI-MS/MS without previous chromatographic separation.

METHODS

Random urine specimens were used for investigation of the analytical imprecision of the method. Recovery, precision and linearity were determined using methanolic standard solutions of free carnitine, octanoylcarnitine and palmitoylcarnitine at various concentrations.

RESULTS

The mean coefficients of variation of within-run and run-to-run analysis of these analytes were found between 10% and 20% and demonstrated that the method fulfills the analytical requirements within the relevant ranges of concentration. Creatinine-related and age-related reference values of free carnitine and the ACs (C2-C18) were established. The definite discrimination was possible between patients with fatty acid oxidation disorders, organic acidurias, and healthy controls. The AC profiles from patients with various specific disorders were diagnostically helpful during acute deterioration and even during conditions of well-compensated metabolic state.

CONCLUSION

The method used in this study is suitable both for selective screening and for confirmation of diagnosis with the advantage of high-throughput quantitative measurement.

Electrospray ionisation mass spectrometry: principles and clinical applications

This mini-review provides a general understanding of electrospray ionisation mass spectrometry (ESI-MS) which has become an increasingly important technique in the clinical laboratory for structural study or quantitative measurement of metabolites in a complex biological sample. The first part of the review explains the electrospray ionisation process, design of mass spectrometers with separation capability, characteristics of the mass spectrum, and practical considerations in quantitative analysis. The second part then focuses on some clinical applications. The capability of ESI-tandem-MS in measuring bio-molecules sharing similar molecular structures makes it particularly useful in screening for inborn errors of amino acid, fatty acid, purine, pyrimidine metabolism and diagnosis of galactosaemia and peroxisomal disorders. Electrospray ionisation is also efficient in generating cluster ions for structural elucidation of macromolecules. This has fostered a new and improved approach (vs electrophoresis) for identification and quantification of haemoglobin variants. With the understanding of glycohaemoglobin structure, an IFCC reference method for glycohaemoglobin assay has been established using ESI-MS. It represents a significant advancement for the standardisation of HbA1c in diabetic monitoring. With its other applications such as in therapeutic drug monitoring, ESI-MS will continue to exert an important influence in the future development and organisation of the clinical laboratory service.

Application of tandem mass spectrometry to biochemical genetics and newborn screening

Tandem mass spectrometry (MS/MS) has become a key technology in the fields of biochemical genetics and newborn screening. The development of electrospray ionisation (ESI) and associated automation of sample handling and data manipulation have allowed the introduction of expanded newborn screening for disorders which feature accumulation of acylcarnitines and certain amino acids in a number of programs worldwide. In addition, the technique has proven valuable in several areas of biochemical genetics including quantification of carnitine and acylcarnitines, in vitro studies of metabolic pathways (in particular beta-oxidation), and diagnosis of peroxisomal and lysosomal disorders. This review covers some of the basic theory of MS/MS and focuses on the practical application of the technique in these two interrelated areas.

Clinical applications of tandem mass spectrometry: ten years of diagnosis and screening for inherited metabolic diseases

This paper reviews the clinical applications of tandem mass spectrometry (MS-MS) in diagnosis and screening for inherited metabolic diseases in the last 10 years. The broad-spectrum of diseases covered, specificity, ease of sample preparation, and high throughput provided by the MS-MS technology has led to the development of multi-disorder newborn screening programs in many countries for amino acid disorders, organic acidemias, and fatty acid oxidation defects. Issues related to sample acquisition, sample preparation, quantification of metabolites, and validation are discussed. Our current experience with the technique in screening is presented. The application of MS-MS in selective screening has revolutionized the field and made a major impact on the detection of certain disease classes such as the fatty acid oxidation defects. New specific and rapid MS-MS and LC-MS-MS methods for highly polar small molecules are supplementing or replacing some of the classical GC-MS methods for a multitude of metabolites and disorders. New exciting applications are appearing in fields of prenatal, postnatal, and even postmortem diagnosis. Examples for pitfalls in the technique are also presented.

Surgery for biliary atresia

Although the prognosis of biliary atresia has been improved in recent years, particularly in the era of liver transplantation, hepatic portoenterostomy, e.g., the Kasai operation, is still the first line of surgical treatment. Successful hepatic portoenterostomy depends on early diagnosis and operation, adequate operative technique, prevention of postoperative cholangitis, and precise postoperative management. The pathophysiology of the liver and of the intrahepatic bile ducts in this disease is still controversial.

Biliary atresia

Although the prognosis of biliary atresia has been dramatically improved in the era of liver transplantation, the Kasai operation is still the first line of surgical treatment. Successful hepatic portoenterostomy depends on early diagnosis and surgery, adequate surgical technique, prevention of cholangitis, and precise postoperative management.

Cholestatic syndromes

Continued advances in the field of liver cell biology and molecular biology have provided further insights into the normal physiology of bile secretion and the pathogenesis and therapy for cholestatic syndromes. Important new data have also been published about pathogenesis, clinical features, and treatment of primary biliary cirrhosis, primary sclerosing cholangitis, drug-induced cholestasis, and cholestatic syndromes caused by viral infections.