Acute Illness Protocol for Urea Cycle Disorders

Mapping challenges in the accessibility of treatment products for urea cycle disorders: A survey of European healthcare professionals

Current management guidelines for urea cycle disorders (UCDs) offer clear strategies, incorporating both authorized and non-authorized medicinal products (including intravenous formulations and products regulated as food). These varying product categories are subject to specific accessibility challenges related to availability, reimbursement, and pricing. The aim of this study is to identify potential obstacles to optimal UCD treatment implementation in European clinical practice. A survey aimed at metabolic healthcare professionals (HCPs) managing patients with UCDs in Europe was disseminated through the European Reference Network for Hereditary Metabolic Disorders and the European registry and network for intoxication type metabolic diseases. Forty-eight survey responses were collected from 21 European countries. In 16 of these countries, at least one metabolic HCP reported challenges in accessing UCD products. Reimbursement issues were reported for most products (8/10), including both authorized and non-authorized products. Availability-related challenges were also reported for 8/10 products, although unavailability was limited to non-authorized products. Prices impacted accessibility for all authorized products (3/3) and one non-authorized IV product. The accessibility of UCD treatment products varied across Europe, although no clear regional variations could be discerned. Survey data revealed that metabolic HCPs experience challenges in accessing both authorized and non-authorized products for UCD management in the majority of European countries. This indicates that registering unauthorized products may not resolve all issues. Improved reimbursement policies and fair pricing models, as well as (adjusted) authorization procedures may help address these concerns, thereby optimizing treatment access for UCD patients.

Urea cycle disorders in critically Ill adults

PURPOSE OF REVIEW

Urea cycle disorders (UCDs) cause elevations in ammonia which, when severe, cause irreversible neurologic injury. Most patients with UCDs are diagnosed as neonates, though mild UCDs can present later - even into adulthood - during windows of high physiologic stress, like critical illness. It is crucial for clinicians to understand when to screen for UCDs and appreciate how to manage these disorders in order to prevent devastating neurologic injury or death.

RECENT FINDINGS

Hyperammonemia, particularly if severe, causes time- and concentration-dependent neurologic injury. Mild UCDs presenting in adulthood are increasingly recognized, so broader screening in adults is recommended. For patients with UCDs, a comprehensive, multitiered approach to management is needed to prevent progression and irreversible injury. Earlier exogenous clearance is increasingly recognized as an important complement to other therapies.

SUMMARY

UCDs alter the core pathway for ammonia metabolism. Screening for mild UCDs in adults with unexplained neurologic symptoms can direct care and prevent deterioration. Management of UCDs emphasizes decreasing ongoing ammonia production, avoiding catabolism, and supporting endogenous and exogenous ammonia clearance. Core neuroprotective and supportive critical care supplements this focused therapy.

Undifferentiated non-hepatic hyperammonemia in the ICU: Diagnosis and management

Hyperammonemia occurs frequently in the critically ill but is largely confined to patients with hepatic dysfunction or failure. Non-hepatic hyperammonemia (NHHA) is far less common but can be a harbinger of life-threatening diagnoses that warrant timely identification and, sometimes, empiric therapy to prevent seizures, status epilepticus, cerebral edema, coma and death; in children, permanent cognitive impairment can result. Subsets of patients are at particular risk for developing NHHA, including the organ transplant recipient. Unique etiologies include rare infections, such as with Ureaplasma species, and unmasked inborn errors of metabolism, like urea cycle disorders, must be considered in the critically ill. Early recognition and empiric therapy, including directed therapies towards these rare etiologies, is crucial to prevent catastrophic demise. We review the etiologies of NHHA and highlight the first presentation of it associated with a concurrent Ureaplasma urealyticum and Mycoplasma hominis infection in a previously healthy individual with polytrauma. Based on this clinical review, a diagnostic and treatment algorithm to identify and manage NHHA is proposed.

Emergency Laboratory Evaluations for Patients With Inborn Errors of Metabolism

BACKGROUND

Children with inborn errors of metabolism (IEM) are at risk for metabolic crises triggered by acute illnesses. Crises are identified through laboratory evaluations.

OBJECTIVES

Our objective was to determine national adherence to minimum laboratory evaluations for patients with IEM in emergency departments (EDs), as well as factors associated with laboratory evaluation adherence.

METHODS

Using the Pediatric Health Information System, we identified visits to 48 EDs from 2012 to 2017 by children with IEM. We analyzed visits for catabolic conditions (dehydration, gastroenteritis, or vomiting) and determined variation in minimum laboratory evaluation adherence. Multivariable models were created to determine predictors of adherence.

RESULTS

Among the visits by children with disorders of the urea cycle, organic acid metabolism, and fatty acid oxidation, 1457 (76.3%) of 1909 adhered to the minimum laboratory evaluation. Median ED-level adherence was 78.2% (interquartile range, 67.4-92.5). Factors associated with adherence were disorder [fatty acid oxidation vs urea cycle disorder; adjusted odds ratio (aOR), 9.35; 95% confidence interval (CI), 4.07-21.47], annual ED volume of patients with IEM (quartile 4 vs 1; aOR, 3.58; 95% CI, 1.51-8.49), and presence of a biochemical genetics fellowship (aOR, 0.29; 95% CI, 0.14-0.62).

CONCLUSIONS

Patients with IEM frequently did not receive minimum laboratory evaluations for catabolic conditions. Measures to improve laboratory use in children with IEM should be undertaken.

A generic emergency protocol for patients with inborn errors of metabolism causing fasting intolerance: A retrospective, single-center study and the generation of www.emergencyprotocol.net

Patients with inborn errors of metabolism causing fasting intolerance can experience acute metabolic decompensations. Long-term data on outcomes using emergency letters are lacking. This is a retrospective, observational, single-center study of the use of emergency letters based on a generic emergency protocol in patients with hepatic glycogen storage diseases (GSD) or fatty acid oxidation disorders (FAOD). Data on hospital admissions, initial laboratory results, and serious adverse events were collected. Subsequently, the website www.emergencyprotocol.net was generated in the context of the CONNECT MetabERN eHealth project following multiple meetings, protocol revisions, and translations. Representing 470 emergency protocol years, 127 hospital admissions were documented in 54/128 (42%) patients who made use of emergency letters generated based on the generic emergency protocol. Hypoglycemia (here defined as glucose concentration < 3.9 mmol/L) was reported in only 15% of hospital admissions and was uncommon in patients with ketotic GSD and patients with FAOD aged >5 years. Convulsions, coma, or death was not documented. By providing basic information, emergency letters for individual patients with hepatic GSD or the main FAOD can be generated at www.emergencyprotocol.net, in nine different languages. Generic emergency protocols are safe and easy for home management by the caregivers and the first hour in-hospital management to prevent metabolic emergencies in patients with hepatic GSD and medium-chain Acyl CoA dehydrogenase deficiency. The website www.emergencyprotocol.net is designed to support families and healthcare providers to generate personalized emergency letters for patients with hepatic GSD and the main FAOD.

Paroxysmal spasticity of lower extremities as the initial symptom in two siblings with maple syrup urine disease

Maple syrup urine disease (MSUD) is a rare autosomal recessive metabolic disorder caused by mutations in genes that encode subunits of the branched‑chain α‑ketoacid dehydrogenase (BCKD) complex. Impairment of the BCKD complex results in an abnormal accumulation of branched‑chain amino acids and their corresponding branched‑chain keto acids in the blood and cerebrospinal fluid, which are neurovirulent and may become life‑threatening. An 11‑day‑old boy was admitted to the hospital with paroxysmal spasticity of lower extremities. Of note, his 10‑year‑old sister presented similar symptoms during the neonatal period, and her condition was diagnosed as MSUD when she was 1.5 years old. Genetic screening was performed, and the boy and his sister exhibited two novel compound heterozygous mutations in the branched chain keto acid dehydrogenase E1 subunit β (BCKDHB) gene: A substitution from guanine to adenine in the coding region at position 1,076 (c.1,076G>A) in exon 10 and a deletion of a thymine at position 705 (c.705delT) in exon 6. The missense mutation c.1076G>A results in an amino acid substitution from arginine to lysine at position 359 (p.Arg359Lys), whereas the mutation c.705delT results in the replacement of a cysteine at position 235 with a stop codon (p.Cys235Ter). Neither of the BCKDHB alleles in the compound heterozygote patients is able to generate normal E1β subunits, resulting in a possible impairment of the activity of the BCKD complex. In the present study, it was hypothesized that the two novel heterozygous mutations in the BCKDHB gene found in the Chinese family may be responsible for the phenotype of the two siblings with MSUD.