6-Thioguanine Levels in Autoimmune Hepatitis

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.

Related blog entries:

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

Neonatal Cholestasis for Neonatologists

I recently had the opportunity to review the topic of neonatal cholestasis with my neonatal colleagues.  I reviewed two related conditions: parenteral nutrition associated liver disease (PNALD) and neonatal acute liver failure (NALF).  Some of the material incorporates recommendations from NASPGHAN cholestasis guidelines and from NASPGHAN cholestasis slidesets. Much of the slideset information is publicly available on a YouTube lecture by Dr. Linda Book (link at bottom).

Full lecture: Neonatal Cholestasis for Neonatologists

Some screenshots:

Related blog posts:

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.

 

Predicting Future Liver Disease with GGT Levels in Biliary Atresia Patients

A recent study (AJ Freeman, VL Ng, S Harpavat, A Hrycko, Z Apted, P Bulut, T Leong, SJ Karpen. Clin Gastroenterol Hepatol 2017; 15: 1133-35) describes the predictive value of γ-glutamyltransferase (GGT) in predicting thrombocytopenia/portal hypertension among biliary atresia patients.

In this retrospective study from three centers who had followup for at least 4 years, GGT values at 2 years of age were examined among biliary atresia patients (n=46) who continued with their native liver.

Key findings:

  • GGT ≥100 U/L had a predictive positive relationship with thrombocytopenia at 4, 5, and 6 years of age.  Patients with elevated GGT had lower platelet count (160 vs. 211) and their values continued to decline. GGT ≥100 U/L at 2 yrs predicted thrombocytopenia (<150) at age 4 with a sensitivity of 0.88, specificity of 0.57.
  • Patients with normal GGT values had “essentially stable platelet counts over the next 4 years.” GGT <100 U/L at 2 yrs predicted a low risk of thrombocytopenia with negative predictive value of 0.89, 0.92, and 0.93 at age 4, 5, and 6 respectively.

My take: This study quantitates a useful point –patients with biliary atresia and elevated GGT values are likely to develop evidence of portal hypertension.

Brevard, NC

Briefly Noted: Outpatient Liver Biopsy

A small retrospective study (R Bolia et al. JPGN 2017; 65: 86-88) with 497 patients (626 biopsies) found that all complications were identified within 8 hours.  Thirty (48%) had complications, with a subcapsular hematoma being most common (n=14).  Less common adverse events included fever (n=5), skin site ooze (n=3), intraperitoneal bleeding (n=3), hemobilia (n=2), anaphylaxis to gelfoam (n=2), and sepsis (n=1). In this study, the majority of biopsies were performed by interventional radiology (n=492); though, the complication rate was similar in both groups.

The authors conclude that their data support the outpatient liver biopsies in children.

My take: I disagree with the authors’ conclusion to some extent.  Their population is too small to detect rare but severe complications.  Our empiric practice is watch children older than 6 years of age for 6 hours and watch younger children (or others deemed at increased risk) for 24 hours.

Related blog posts:

Prague

Slim Pickings: Data for 2nd-Line Autoimmune Hepatitis Pediatric Therapy

A recent study (AN Zizzo et al. JPGN 2017; 65: 6-15) performed a systematic review and meta-analysis of pediatric autoimmune hepatitis (AIH) studies.

The most remarkable finding was that there were only 76 patients from 15 qualifying studies.

Other findings:

  • Response to mycophenolate mofetil (MMF) with 34 patients was 36% (according to abstract) at 6 months  (discrepancy in article –results state 38% response)
  • Response to cyclosporine with 15 patients was 83% (discrepancy in article –results state 86% response)
  • Response to tacrolimus with 4 patients was 50%
  • Adverse effects were very common, particularly with cyclosporine (64% noted at least 1 adverse effect)

The article has an associated editorial (N Kerkar, pg 2-3).  “The adverse event profile of cyclosporine with gingival hyperplasia, hypertrichosis, nephrotoxicity, and neurotoxicity made it challenging for long-term use in children.”  Besides the small number of patients, “the studies that were included were largely “observational”‘ which limits their findings as well.  The study authors recommend MMF as the preferred option for 2nd-line therapy.

My take: Fortunately, most patients with autoimmune hepatitis respond to first line therapy with azathioprine/steroids.  It is unclear what is the optimal 2nd-line treatment for refractory patients.

Related blog entries:

Egret, Shem Creek

Hepatitis B Reactivation Due to Immunosuppressive Therapies

The topic of Hepatitis B virus (HBV) reactivation has been discussed on this blog before (see link below).  Another excellent review on this topic (R Lomba, TJ Liang. Gastroenterol 2017; 152: 1297-1309) has been published.  The authors examine the course and mechanisms of HBV reactivation.  They divide the risk of reactivation into three groups: high, moderate and low risk and proposed management.

High risk groups, which have >10% risk of reactivation) include the following

  • B-cell-depleting agents including rituximab, ofatumumab, alemtuumab, and ibritumumab
  • High-dose corticosteroids (>20 mg/day in adults)
  • Antracyclines including doxorubicin
  • Potent TNF-α inhibitors: infliximab, adalimummab, certolizumab, and golimumab
  • Local therapy ofr HCC including TACE (transarterial chemoembolization)

Moderate groups (1-10% reactivation) include cytokine-based Rx (eg. abatacept, ustekinumab, natalizumab, vedolizumab), cyclosporine, systemic chemotherapy, moderate corticosteroid dosing

Low risk groups (<1% reactivation) include thiopurines (azathioprine, 6-mercaptopurine), and methotrexate as well as short-term low-dose corticosteroids.

Management:

  • For HBV screening, the authors recommend HBsAg and anti-HBc testing
  • Prophylactic therapy with potent oral anti-HBV therapies are recommended for those at moderate or high risk of reactivation.  In those at low risk, the options include prophylactic treatment or watchful monitoring.
  • A more detailed algorithm is provided in Figure 3.  In those with HBsAg positivity, if HBV DNA is less than 2000 U/mL, this algorithm suggests monitoring labs (HBsAg, ALT, HBV DNA every 3 months)

Mechanisms of HBV reactivation are discussed.  For example, with TNF-α inhibitors “can activate a unique host antiviral pathway, the APOBEC (apolipoprotein B mRNA editing enzyme, catlytic polypeptide-like) proteins, that cause the degradation of cccDNA in HBV-infected cells. Thus, blocking this endogenous antiviral pathway may lead to a higher HBV replication state and HBV reactivation.”

My take: In pediatric gastroenterology, we do not see a lot of HBV reactivation. Nevertheless, we do use many of the medications which can trigger HBV reactivation and need to keep these recommendations in mind.

Related blog post: What HBV Testing is Needed Before TNF Inhibitor Therapy

Suntrust Park

Acute Liver Failure -Pediatric ICU Management

Full Text Link: Intensive Care Management of Acute Liver Failure

This article provides a very good overview of this topic starting withe diagnosis, epidemiology and proceeding to specific management issues/outcomes.

Table 1 reviews etiologies –indeterminant is most common. Table 2 shown below reviews management principles and Table 3 reviews specific treatments based on etiology. Table 4 reviews grades of encephalopathy.

My take (from authors): “Despite recent advances in supportive care and the improvements in outcomes observed…the practical intensive care management of PALF remains poorly defined…Current treatment options are merely supportive and based on incomplete adult data and local institutional experience.”

Related blog posts: