Category Archives: Pediatric Gastroenterology Liver Disease

Pediatric Liver Transplantation: Past Time to Split

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A recent study (EK Hsu et al. Gastroentorol 2017; 153: 988-95, editorial 888-89) exposes some deep flaws in organ transplantation in U.S.

The retrospective study examined children on the U.S liver transplant wait-list from 2007-14.  This included 3852 pediatric candidates.  Key findings:

  • Of 27,831 adults who underwent transplantation, 1667 (6%) received livers from pediatric donors (<18 years)
  • Of children who died or were delisted, the centers caring for 173 (55%) had received an offer of 1 or more livers that was subsequently transplanted into another pediatric recipient.  The remaining 45% died or delisted with no offers. High-volume (>15 transplants per year) centers were more likely to accept an organ than a low-volume center (<5 transplants per year).
  • Only 29% of children received a split graft.  When a splittable adult liver graft was allocated to an adult the chance of it being used as a split was 0.6%.

Background:

  • Children have much lower survival rate than adults on waiting list. Of adults who died or delisted, 85% receive at least one transplant offer; whereas, nearly half of all children never even receive an offer.  Children who died/delisted had wait-time of 33 days compared with 92 days for adults who died/delisted.
  • Less than 10% of all liver transplant recipients are pediatric transplants.  Per editorial, “a measure that improves pediatric access by 20% would only reduce adult access by 2%.”
  • There are more than 100 pediatric liver transplant centers in U.S. Certainly, this improves convenience; however, per editorial:  “three-fourths are very low volume centers, performing <5 liver transplantations per year…Death on waiting list” occur 5 times more at low-volume transplantation centers.
  • In this study, only 29% of children received split livers; in comparison, in the UK, >80% receive either a split graft or living donor graft.

The editorial points out that splittable livers that are allocated to adults are virtually never split; this is either due to inconvenience or lack of expertise.  A small increase in liver splitting would dramatically lower the pediatric mortality wait list.  There is no incentive in the current system to split a liver/save a child’s life.

My take: The data from this study points out glaring problems in pediatric liver transplantation.

  1. Children are dying due to lack of prioritization.  Pediatric livers are going to adults.
  2. There is practically no splitting when liver organs are allocated to an adult.  Incentives to increase organ splitting would save many children from dying waiting for an organ.
  3. Large volume pediatric centers are much more likely to accept a liver offer for patients waiting at their centers.  There is an increased wait-list mortality at very low volume centers, perhaps due to lack of expertise and passing up viable organs.  Do hepatologists/surgeons at these centers explain this risk to families at their centers?

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Assessing Neonatal Jaundice with Smartphone App

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A recent study (Taylor JA, et al. Pediatrics 2017; 140 (3) e20170312) reports on the effectiveness of a smartphone app, BiliCam, to detect total serum bilirubin (TSB) in a diverse sample of newborns < 7 days old.  Thanks to Ben Gold for this reference.

BiliCam uses a calibration card which is placed on the infant’s sternum to standardize the color (and jaundice) reading in the photo; the image goes via the internet to a server for analysis.

Key findings:

  • Estimated bilirubin levels using BiliCam were compared with TSB levels in 530 newborns which included 20.8% African American,, 26.3% Hispanic and 21.2% Asian American
  • The overall correlation was 0.91 were similar among all ethnic groups with correlations ranging from 0.88 to 0.92
  •  The sensitivity of Bilicam was 84.6% is for identifying infants with a TSB in the high-risk zone of the Bhutani nomogram. The sensitivity was 100% for identifying TSB > 17 mg/dL. Specificities were 75.1% adn 76.4% respectively.

For more commentary on this article: AAP Journals Blog: Bilirubin phone apps –our future calls!

My take: This article indicates that a digital image with Smartphone app analysis is much more accurate in detecting jaundice that a visual assessment.

Bile Acid Therapy -18 Year Study

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JE Heubi et al (JPGN 2017; 65: 321-6) performed a phase 3, open-label, nonrandomized trial on the efficacy and safety of oral cholic acid for patients with Zellweger Spectrum disorders (n=20) and patients with bile acid synthesis disorders (BASD) (n=50). Cholic acid dosing: 10-15 mg/kg/day. Most common BASD were 3β-HSD (n=35), and 5β-reductase (n=10).  Based on this work, cholic acid is an FDA-approved agent.

Key findings:

  • Urine bile acid metabolite scores improved (P<0.0001) with cholic acid
  • Transaminases improved (AST, ALT) (P<0.0001)
  • Growth parameters, improved with weight gain reaching statistical significance
  • “Liver biopsies showed either stable findings or histologic improvement in all parameters except bridging fibrosis”
  • No study drug-related serious adverse events were noted
  • With Zellweger spectrum disorders, it is important to note that “there is no evidence that treatment with cholic acid has any impact on the extrahepatic disease.”

My take: Cholic acid helps the liver in these disorders which is particularly important for BASD. It is unclear if this improves outcomes in patients with Zellweger spectrum disorders as it has not been shown to improve extrahepatic disease.

Related blog post:

Eiffel Tower

Fructose Restriction Improved Fatty Liver Disease in Children

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A recent study (J-M Schwarz et al. Gastroenterol 2017; 153: 743-52, editorial MB Vos, IR Goran Gastroenterol 2017; 153: 642-5 ) showed that restriction of fructose quickly improved fatty liver disease.

Several points from the editorial:

  • “The metabolic driver of buildup of fat storage in the liver is de novo lipogenesis (DNL) and fructose is a major substrate of DNL”
  • “In the healthy state, DNL is not expected to be a major contributor to lipid accumulation in the liver….[but] in a fatty liver, it has been estimated that 26% of the fat originates from DNL.”
  • Fructose is “limited in a natural diet…However, it is added to many processed foods and drinks in the form of cane sugar..and other types of sugars, going by ≥57 different names.”
  • Fructose is “commonly used in animal models to induce hepatic steatosis.”

The study is summarized in a recent AGA Journals Blog: Can Restricting Fructose Intake Reduce Fatty Liver Disease in Children?

An excerpt:

Jean-Marc Schwarz et al performed a clinical trial to investigate the effects of reducing fructose intake for 9 days in obese Latino and African American children with habitual high sugar consumption (fructose intake >50 g/day). They measured the effects of isocaloric fructose restriction on de novo lipogenesis, liver fat, visceral fat, subcutaneous fat, and insulin kinetics.

In their study, 41 children, 9−18 years old, had all meals provided for 9 days. The meals had the same energy and macronutrient composition as their standard diet, but with starch substituted for sugar, yielding a final fructose content of 4% of total kilocalories. The authors measured metabolic factors before and after fructose restriction. They measured liver fat, visceral fat, and subcutaneous fat by magnetic resonance spectroscopy and imaging.

Schwarz et al found that on day 10 of the diet, liver fat decreased from a median 7.2% at baseline to 3.8%, and visceral fat decreased from 123 cm3  at baseline to 110 cm3. Liver fat decreased in all but 1 of the 38 participants for whom paired data were available…

De novo lipogenesis decreased significantly after 9 days of fructose restriction; the de novo lipogenesis area under the curve value on day 10 decreased from 68% at baseline to 26% after the diet, in childen with low or high baseline levels of liver fat.

Insulin secretion during fasting and in response to an oral glucose tolerance test decreased significantly in children with low and high baseline levels of liver fat…

In an editorial that accompanies the article, Miriam B. Vos and Michael I. Goran say that it will be important to determine whether the effects of fructose reduction are sustained past 9 days…Vos and Goran state that it is important for physicians, nutritionists, schools, and parents to find ways to reduce fructose in the diets of children and patients with NAFLD.

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Moving Away from Liver Biopsies

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A recent review (EB Tapper, AS-F Lok. NEJM 2017; 377: 756-68) provides a good review of liver biopsy and liver imaging. My take of this review is that it highlights the emergence of noninvasive tools (imaging & fibrosis markers) which may supplant liver biopsy.  This article does not delve into how more widespread genetic testing may obviate a liver biopsy in many cases as well. The article notes that about 8% of persons in the U.S. have elevated liver enzymes.

Liver biopsy:

  • “A typical liver biopsy samples one fifty-thousandth of the liver.”
  • Limitations of liver biopsy: sampling error is common, biopsy interpretation is subjective, and biopsies can cause complications.  Pain is noted in 30-50% of patients, serious bleeding in 0.6%, injury to other organs (0.08%), and in rare cases, death (up  to 0.1%).
  • Cost: “the average direct cost of a percutaneous liver biopsy is $1448 (in 2016 U.S. dollars).” Transjugular biopsies are much more expensive.  In addition, there are unmeasured indirect costs, due to missing work.

Some prior blogs on liver biopsy

Blood tests:

  • The article details the formulas for biomarker measurements that predict the risk of fibrosis, inlcuding FIB-4, Lok Index, and NAFLD Fibrosis Score.
  • In most liver diseases, aspartate aminotransferase levels “exceed alanine aminotransferase levels when cirrhosis develops.”
  • Thrombocytopenia “is the earliest indicator of cirrhosis among routine blood tests…[due to] diminished liver function (throbopoietin underproduction) and portal hypertension (splenic sequestration).”
  • Proprietary algorithms to assess fibrosis have variable sensitivity, specificity –include FibroTest (aka FibroSure [LabCorp]), FibroMeter, HepaScore (Quest), FIBROSpect, and the Enhanced Liver Fibrosis Score.

Imaging:

  • Elastography with vibration-controlled transient elastography (VCTE) OR magnetic resonance elastography
  • “Elastography offers excellent negative likelihood ratios for advanced fibrosis but much poorer positive likelihood ratios.”
  • Patients with severe obesity are less likely to obtain adequate study with VCTE and could need magnetic resonance elastography to assess fibrosis.

My take: Noninvasive tests have already sharply reduced the need for liver biopsy.

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Updated Biliary Atresia Epidemiology

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A recent retrospective study (PC Hopkins, N Yazigi, CM Nylund. J Pediatr 2017; 187: 253-7) provides an update on the recent incidence of biliary atresia in the US from 1997-2012. This study relied on coding for biliary atresia or Kasai hepatoportoenterostomy to identify cases using HCUP-KID database.  This database provides a nationally representative sample of pediatric hospitalizations and captures ~96% of pediatric hospitalizations in the US.

Key findings:

  • Incidence of biliary atresia (BA) was 4.47 per 100,000 (1 in 22,371 infants)
  • BA was more common in females (RR 1.43), Asian/Pacific Islanders (RR 1.89), and blacks (RR 1.30)
  • Median age at the time of the Kasai procedure was 63 days with no improvement over the course of the study period.  More than 50% of all children underwent the Kasai procedure after the optimal window of 60 days of life

My take: In my view, at this time, obtaining a blood test for direct bilirubin in the first two weeks of life will need to be adopted broadly if we are going to diagnose biliary atresia at an earlier age.

Related blog posts:

Dry Falls, Highlands NC

Dry Falls, Highlands NC

 

Recurrent Acute Liver Failure due to NBAS Deficiency

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A recent case report (V Cardenas et al. J Pediatr 2017; 186: 179-82) describes recurrent acute liver failure (ALF) in the setting of neuroblastoma amplified sequence deficiency (NBAS).

The case report describes a 2 yo who developed very elevated aminotransferases (ALT >14,000), hypoglycemia, severe coagulopathy (INR 4.5)), lactic acidosis (6.5 mmol/L) and hyperammonemia (282 μmol/L) following a febrile illness.

Genetic testing uncovered 2 variants in the NBAS gene consistent with NBAS deficiency.

Key points:

  • Mutations in NBAS “have been identified as a molecular cause of ALF in children, leading to recurrent episodes of ALF after a febrile illness.”
  • NBAS deficiency should be part of the differential diagnosis of ALF in children
  • In a report of 14 patients with this disorder (J Inherit Metab Dis 2016; 39: 3-16), liver function normalized in between episodes.  Typically, episodes were most severe at younger ages.  ALF “may be prevented through early and effective antipyretic therapy and intravenous application of glucose and lipids.”

My take: NBAS deficiency, along with hemophagocytic lymphohistiocytosis (HLH), infections, and Kawasaki’s disease, needs to be considered in children with severe liver dysfunction associated with fevers.

“Big Improvements for Smallest Recipients” with Bad Liver Disease

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A recent study (M Kasahara et al. Liver Transplantation 2017; 23: 1051-7, editorial 977-8) indicates improvement in survival among the smallest liver transplant patients. In this study of 12 patients less than 3 months of age, the cumulative 10-year patient and graft survival for both was 90.9%.

These patients received living donor liver transplantation. Living donors likely contributed to the excellent outcomes both in terms of enhancing the timing of transplantation and also with regard to size.  Whole organs are not likely to fit well in these small abdomens. The size of the patients ranged from 2.8 kg (at 29 days) to 5.5 kg).  11 of 12 had fulminant hepatic failure with 6 of these cases being considered unknown etiology.

Limitation: This was a very small sample size.

Programming for Fatty Liver Disease May Occur Prior to Birth

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A recent study (KP Newton et al. J Pediatr 2017; 187: 141-6; associated editorial pg 13-15)) in a multicenter retrospective cross-sectional study of children (n=538) with biopsy-proven nonalcoholic fatty liver disease (NAFLD) showed that birth weight influenced the development of NAFLD.  The participants were enrolled in the Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN).

Key findings:

  • There was increased NAFLD among both low birth weight (LBW) and high birth weight (HBW).
  • LBW occurred more commonly in the NAFLD cohort 9.3% compared with the general population prevalence 6.1%.
  • HBW occurred more commonly in the NAFLD cohort 14.9% compared with the general population prevalence 10.5%

The authors speculate that the explanation/mechanisms for increase in both LBW and HBW are likely to differ. It has been recognized that LBW is associated with higher cardiovascular disease and type 2 diabetes.  HBW start bigger and often stay bigger; that is, there are increased risks of more severe obesity.

There are numerous limitations to this study -there is a lot of data that is not available, including gestational age, maternal weight, breastfeeding exposure, and antibiotic administration.

My take: These findings add to the literature that risks for NAFLD along with other metabolic problems may be present at birth.  Is there a way to modify this risk?

Related study: ET Jensen et al. J Pediatr 2017; 187: 50-7, editorial pg 10-12.  In this study of 535 ten-year-old children, enrolled in a prospective multicenter extremely low gestational age newborn cohort study, the authors found that maternal overnutrition and undernutrition affected the brain health of these children. The authors used neurocognitive assessment tools.

  • Children born to women with a pregravid BMI >30 scored “lower on measures of general cognitive ability, executive functioning, fine motor function, and academic achievement.”
  • Children born to women with inadequate maternal weight gain during pregnancy had “lower language and academic achievement.”

Hidden Falls, Highlands NC

 

6-Thioguanine Levels in Autoimmune Hepatitis

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A recent retrospective study (MA Sheiko et al JPGN 2017; 65: 80-5) examines the issue of azathioprine (AZA) metabolites and outcomes in pediatric autoimmune hepatitis (AIH).

Study characteristics:

  • 66 children
  • Mean age of diagnosis 9.6 years
  • Mean follow-up 2.9 years
  • Study period 2002-2013

Key findings:

  • 79% achieved biochemical remission (defined as ALT ≤50 U/L); mean time was 6.2 months
  • 6% required liver transplantation
  • 18% were weaned off immunosuppression and remained in remission
  • 6-thioguanine (6-TGN) levels ranging from 50 to 250 (pmol/8 x 10 to 8th red blood cell count) were associated with biochemical remission

“Our study suggests that AZA dosing of approximately 1.2 to 1.6 mg/kg/day will achieve 6-TGN levels of 50 to 250 pmol, which is sufficient to maintain biochemical remission in the majority of patients.“

This is significantly lower than dosing recommended for inflammatory bowel disease (recommended levels 250-450). The associated editorial (pg 2-3, N Kerkar) cautions that while “lower levels are sufficient for maintaining biochemical remission…higher levels, similar to that used in IBD, are required for inducing remission.”

My take: Lower doses of azathioprine are likely to maintain biochemical remission and cause fewer side effects.  Metabolite levels can be helpful to assure reasonable levels of 6-TGN and to assure medication adherence.

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Disclaimer: These blog posts are for educational purposes only. Specific dosing of medications (along with potential adverse effects) should be confirmed by prescribing physician.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

Shem Creek, SC