Chronic pancreatitis in branched-chain organic acidurias--a case of methylmalonic aciduria and an overview of the literature

Long-term renal outcome in methylmalonic acidemia in adolescents and adults

BACKGROUND

Chronic kidney disease (CKD) is one of the main long-term prognosis factors in methylmalonic acidemia (MMA), a rare disease of propionate catabolism. Our objective was to precisely address the clinical and biological characteristics of long-term CKD in MMA adolescent and adult patients.

PATIENTS AND METHODS

In this retrospective study, we included MMA patients older than 13 years who had not received kidney and/or liver transplantation. We explored tubular functions, with special attention to proximal tubular function. We measured glomerular filtration rate (mGFR) by iohexol clearance and compared it to estimated glomerular filtration rate (eGFR) by Schwartz formula and CKD-EPI.

RESULTS

Thirteen patients were included (M/F = 5/8). Median age was 24 years (13 to 32). Median mGFR was 57 mL/min/1.73 m2 (23.3 to 105 mL/min/1.73 m2). Ten out of 13 patients had mGFR below 90 mL/min/1.73 m2. No patient had significant glomerular proteinuria. No patient had complete Fanconi syndrome. Only one patient had biological signs suggestive of incomplete proximal tubulopathy. Four out of 13 patients had isolated potassium loss, related to a non-reabsorbable anion effect of urinary methylmalonate. Both Schwartz formula and CKD-EPI significantly overestimated GFR. Bias were respectively 16 ± 15 mL/min/1.73 m2 and 37 ± 22 mL/min/1.73 m2.

CONCLUSION

CKD is a common complication of the MMA. Usual equations overestimate GFR. Therefore, mGFR should be performed to inform therapeutic decisions such as dialysis and/or transplantation. Mild evidence of proximal tubular dysfunction was found in only one patient, suggesting that other mechanisms are involved.

Guidelines for the diagnosis and management of methylmalonic acidaemia and propionic acidaemia: First revision

Isolated methylmalonic acidaemia (MMA) and propionic acidaemia (PA) are rare inherited metabolic diseases. Six years ago, a detailed evaluation of the available evidence on diagnosis and management of these disorders has been published for the first time. The article received considerable attention, illustrating the importance of an expert panel to evaluate and compile recommendations to guide rare disease patient care. Since that time, a growing body of evidence on transplant outcomes in MMA and PA patients and use of precursor free amino acid mixtures allows for updates of the guidelines. In this article, we aim to incorporate this newly published knowledge and provide a revised version of the guidelines. The analysis was performed by a panel of multidisciplinary health care experts, who followed an updated guideline development methodology (GRADE). Hence, the full body of evidence up until autumn 2019 was re-evaluated, analysed and graded. As a result, 21 updated recommendations were compiled in a more concise paper with a focus on the existing evidence to enable well-informed decisions in the context of MMA and PA patient care.

Pancreatic involvement in patients with inborn errors of metabolism

Background

Repeated inflammation of the pancreas can cause pancreatitis or diabetes. It is well recognized that the organic acidemias may be complicated by pancreatitis but less recognized are other metabolic disorders in which pancreatitis can occur. This study shows that long-term follow-up of patients with various metabolic disorders in Korea revealed several with episodes of isolated pancreatitis or diabetes concomitantly with pancreatitis.

Results and discussion

In this study, two patients with methylmalonic aciduria (MMA), two with propionic acidemia (PPA), one with fatty acid oxidation disorder (FAOD), and one with hyperornithinemia, gyrate atrophy, and juvenile onset diabetes mellitus (DM) were clinically followed for up to 10 – 21 years. Two Korean siblings with MMA showed recurrent pancreatitis from the age of 15 and 19, respectively. The frequency of admission due to pancreatitis was up to 11 times. One patient with MMA developed diabetes mellitus at the age of 20. The other patient with MMA developed recurrent pancreatitis at 4 years and diabetes at 8 years of age. One of the patients with PPA presented with diabetic ketoacidosis. The other PPA patient died of cardiac arrest at age 10. The patient with FAOD presented with pancreatitis at 10 years and died at the age of 15 years due to cardiac arrest. A 35-year-old woman with hyperornithinemia/gyrate atrophy was diagnosed with juvenile onset diabetes at the age of 7 years. No pancreatitis occurred during the follow-up period.

Conclusions

We conclude that various metabolic disorders can trigger acute or chronic pancreatitis. Proper and prompt multidisciplinary management of metabolic derangement is crucial for preventing pancreatic damage. Further clinical and investigational studies are required to elucidate the pathogenesis of pancreatitis and diabetes mellitus in patients with inborn errors in metabolism.

An expanding spectrum of complications in isolated methylmalonic aciduria

Isolated methylmalonic acidurias represent a heterogeneous genetic group of inborn errors of propionate metabolism with the common biochemical hallmark of elevated methylmalonic acid present in tissues and body fluids. It was first described in the 1960s and over the years better understanding of the disease and its presentation, earlier diagnosis, and most importantly advances in treatment have resulted in extended survival of patients. With that an expanding spectrum of complications is emerging which requires attention and regular monitoring to facilitate early intervention and reduce disease burden.

Optic neuropathy in classical methylmalonic acidemia

Background: Classical MMA, caused by methylmalonyl-CoA mutase deficiency, may result in late-onset dysfunction in several organ systems. To date, 10 cases of optic neuropathy have been reported. The prevalence of optic neuropathy in visually asymptomatic patients has not been determined. This study sought to identify overt and subclinical optic neuropathy in a cohort with classical MMA. Methods and Materials: Neuroophthalmic examinations were performed on 21 patients identified with classical MMA, older than 10years. Diagnosis of optic neuropathy was determined by a combination of visual acuity, optic nerve appearance and electrodiagnostic tests. Tabulated data were analyzed for association of variables using SAS software. Significance was set at p < .05. Results: Two-thirds were Saudi nationals and one third, Syrian. Age range was 11-29years. Eleven (52.4%) patients had optic neuropathy. Nine (81.8%) of these were bilateral, seven (57.9% to 63.6%) reported decreased vision and four (33.1% to 36.4%) were asymptomatic. Two patients had catastrophic vision loss, following acute metabolic crises. Sixteen patients had chronic renal impairment while three had renal hypertension. Seventeen patients had short stature and eight, chronic pancreatitis. Methylmalonic acid levels ranged from 82 to 3,324µmol/L (Normal<1µmol/L). There was a significant association between optic neuropathy and female gender (p = .011) and none with age, nationality, renal impairment, pancreatitis or specific genotype. Conclusion: Optic neuropathy was a frequent finding in classical MMA. It was often bilateral and some cases were sub-clinical, lacking visual symptoms. These findings have important management implications. Full ophthalmic evaluations should be performed early and regularly in patients with MMA, even when patients are asymptomatic.

Fibroblast growth factor 21 as a biomarker for long-term complications in organic acidemias

BACKGROUND

There is increasing evidence that long-term complications in organic acidemias are caused by impaired mitochondrial metabolism. Currently, there is no specific biomarker to monitor mitochondrial dysfunction in organic acidemias. Serum fibroblast growth factor 21 (FGF-21) is a biomarker for mitochondrial disease and could be a candidate to monitor mitochondrial function in the deleterious course of disease.

METHODS

Data of 17 patients with classical organic acidemias (11 propionic acidemia (PA), four methylmalonic acidemia (MMA) and two isovaleric acidemia (IVA) patients) were included. The clinical course was evaluated; metabolic decompensations and long-term complications were correlated with plasma FGF-21 levels. Cardiomyopathy, prolonged QT interval, renal failure, and optic neuropathy were defined as long-term complications.

RESULTS

Patients ages ranged from 16 months up to 32 years. Serious long-term complications occurred in eight patients (five PA and three MMA patients). In MMA and PA patients plasma FGF-21 levels during stable metabolic periods were significantly higher in patients with long-term complications (Mdn = 2556.0 pg/ml) compared to patients without (Mdn = 287.0 pg/ml). A median plasma FGF-21 level above 1500 pg/ml during a stable metabolic period, measured before the occurrence of long-term complications, had a positive predictive value of 0.83 and a negative predictive value of 1.00 on long-term complications in MMA and PA patients.

CONCLUSION

This study demonstrates the potential role of FGF-21 as a biomarker for long-term complications in classical organic acidemias, attributed to mitochondrial dysfunction.

Organic acidurias in adults: late complications and management

Organic acidurias (synonym, organic acid disorders, OADs) are a heterogenous group of inherited metabolic diseases delineated with the implementation of gas chromatography/mass spectrometry in metabolic laboratories starting in the 1960s and 1970s. Biochemically, OADs are characterized by accumulation of mono-, di- and/or tricarboxylic acids ("organic acids") and corresponding coenzyme A, carnitine and/or glycine esters, some of which are considered toxic at high concentrations. Clinically, disease onset is variable, however, affected individuals may already present during the newborn period with life-threatening acute metabolic crises and acute multi-organ failure. Tandem mass spectrometry-based newborn screening programmes, in particular for isovaleric aciduria and glutaric aciduria type 1, have significantly reduced diagnostic delay. Dietary treatment with low protein intake or reduced intake of the precursor amino acid(s), carnitine supplementation, cofactor treatment (in responsive patients) and nonadsorbable antibiotics is commonly used for maintenance treatment. Emergency treatment options with high carbohydrate/glucose intake, pharmacological and extracorporeal detoxification of accumulating toxic metabolites for intensified therapy during threatening episodes exist. Diagnostic and therapeutic measures have improved survival and overall outcome in individuals with OADs. However, it has become increasingly evident that the manifestation of late disease complications cannot be reliably predicted and prevented. Conventional metabolic treatment often fails to prevent irreversible organ dysfunction with increasing age, even if patients are considered to be "metabolically stable". This has challenged our understanding of OADs and has elicited the discussion on optimized therapy, including (early) organ transplantation, and long-term care.

Inborn Errors of Metabolism with Acidosis: Organic Acidemias and Defects of Pyruvate and Ketone Body Metabolism

When a child presents with high-anion gap metabolic acidosis, the pediatrician can proceed with confidence by recalling some basic principles. Defects of organic acid, pyruvate, and ketone body metabolism that present with acute acidosis are reviewed. Flowcharts for identifying the underlying cause and initiating life-saving therapy are provided. By evaluating electrolytes, blood sugar, lactate, ammonia, and urine ketones, the provider can determine the likelihood of an inborn error of metabolism. Freezing serum, plasma, and urine samples during the acute presentation for definitive diagnostic testing at the provider's convenience aids in the differential diagnosis.

Aspects of Newborn Screening in Isovaleric Acidemia

Isovaleric acidemia (IVA), an inborn error of leucine catabolism, is caused by mutations in the isovaleryl-CoA dehydrogenase (IVD) gene, resulting in the accumulation of derivatives of isovaleryl-CoA including isovaleryl (C5)-carnitine, the marker metabolite used for newborn screening (NBS). The inclusion of IVA in NBS programs in many countries has broadened knowledge of the variability of the condition, whereas prior to NBS, two distinct clinical phenotypes were known, an "acute neonatal" and a "chronic intermittent" form. An additional biochemically mild and potentially asymptomatic form of IVA and its association with a common missense mutation, c.932C>T (p.A282V), was discovered in subjects identified through NBS. Deficiency of short/branched chain specific acyl-CoA dehydrogenase (2-methylbutyryl-CoA dehydrogenase), a defect of isoleucine degradation whose clinical significance remains unclear, also results in elevated C5-carnitine, and may therefore be detected by NBS for IVA. Treatment strategies for the long-term management of symptomatic IVA comprise the prevention of catabolism, dietary restriction of natural protein or leucine intake, and supplementation with l-carnitine and/or l-glycine. Recommendations on how to counsel and manage individuals with the mild phenotype detected by NBS are required.

Endocrine Dysfunctions in Patients with Inherited Metabolic Diseases

OBJECTIVE

Inherited metabolic diseases (IMDs) can affect many organ systems, including the endocrine system. There are limited data regarding endocrine dysfunctions related to IMDs in adults, however, no data exist in pediatric patients with IMDs. The aim of this study was to investigate endocrine dysfunctions in patients with IMDs by assessing their demographic, clinical, and laboratory data.

METHODS

Data were obtained retrospectively from the medical reports of patients with IMDs who were followed by the division of pediatric metabolism and nutrition between June 2011 and November 2013.

RESULTS

In total, 260 patients [139 males (53%) and 121 females (47%)] with an IMD diagnosis were included in the study. The mean age of the patients was 5.94 (range; 0.08 to 49) years and 95.8% (249 of 260 patients) were in the pediatric age group. Growth status was evaluated in 258 patients and of them, 27 (10.5%) had growth failure, all cases of which were attributed to non-endocrine reasons. There was a significant correlation between growth failure and serum albumin levels below 3.5 g/dL (p=0.002). Only three of 260 (1.1%) patients had endocrine dysfunction. Of these, one with lecithin-cholesterol acyltransferase deficiency and another with Kearns-Sayre syndrome had diabetes, and one with glycerol kinase deficiency had glucocorticoid deficiency.

CONCLUSION

Endocrine dysfunction in patients with IMDs is relatively rare. For this reason, there is no need to conduct routine endocrine evaluations in most patients with IMDs unless a careful and detailed history and a physical examination point to an endocrine dysfunction.

Impact of age at onset and newborn screening on outcome in organic acidurias

BACKGROUND AND AIM

To describe current diagnostic and therapeutic strategies in organic acidurias (OADs) and to evaluate their impact on the disease course allowing harmonisation.

METHODS

Datasets of 567 OAD patients from the E-IMD registry were analysed. The sample includes patients with methylmalonic (MMA, n = 164), propionic (PA, n = 144) and isovaleric aciduria (IVA, n = 83), and glutaric aciduria type 1 (GA1, n = 176). Statistical analysis included description and recursive partitioning of diagnostic and therapeutic strategies, and odds ratios (OR) for health outcome parameters. For some analyses, symptomatic patients were divided into those presenting with first symptoms during (i.e. early onset, EO) or after the newborn period (i.e. late onset, LO).

RESULTS

Patients identified by newborn screening (NBS) had a significantly lower median age of diagnosis (8 days) compared to the LO group (363 days, p < 0.001], but not compared to the EO group. Of all OAD patients 71 % remained asymptomatic until day 8. Patients with cobalamin-nonresponsive MMA (MMA-Cbl(-)) and GA1 identified by NBS were less likely to have movement disorders than those diagnosed by selective screening (MMA-Cbl(-): 10 % versus 39 %, p = 0.002; GA1: 26 % versus 73 %, p < 0.001). For other OADs, the clinical benefit of NBS was less clear. Reported age-adjusted intake of natural protein and calories was significantly higher in LO patients than in EO patients reflecting different disease severities. Variable drug combinations, ranging from 12 in MMA-Cbl(-) to two in isovaleric aciduria, were used for maintenance treatment. The effects of specific metabolic treatment strategies on the health outcomes remain unclear because of the strong influences of age at onset (EO versus LO), diagnostic mode (NBS versus selective screening), and the various treatment combinations used.

CONCLUSIONS

NBS is an effective intervention to reduce time until diagnosis especially for LO patients and to prevent irreversible cerebral damage in GA1 and MMA-Cbl(-). Huge diversity of therapeutic interventions hampers our understanding of optimal treatment.

Toxic-metabolic Risk Factors in Pediatric Pancreatitis: Recommendations for Diagnosis, Management, and Future Research

Pancreatitis in children can result from metabolic and toxic risk factors, but the evidence linking these factors is sparse. We review the evidence for association or causality of these risk factors in pancreatitis, discuss management strategies, and their rationale. We conducted a review of the pediatric pancreatitis literature with respect to the following risk factors: hyperlipidemia, hypercalcemia, chronic renal failure, smoking exposure, alcohol, and medications. Areas of additional research were identified. Hypertriglyceridemia of 1000 mg/dL or greater poses an absolute risk for pancreatitis; persistent elevations of calcium are predisposing. Further research is necessary to determine whether end-stage renal disease leads to increased pancreatitis in children similar to adults. It is unknown whether cigarette smoking exposure, which clearly increases risk in adults, also increases risk in children. The role of alcohol in pediatric pancreatitis, whether direct or modifying, needs to be elucidated. The evidence supporting most cases of medication-induced pancreatitis is poor. Drug structure, improper handling of drug by host, and bystander status may be implicated. Other pancreatitis risk factors must be sought in all cases. The quality of evidence supporting causative role of various toxic and metabolic factors in pediatric pancreatitis is variable. Careful phenotyping is essential, including search for other etiologic risk factors. Directed therapy includes correction/removal of any agent identified, and general supportive measures. Further research is necessary to improve our understanding of these pancreatitis risk factors in children.

The phenotypic spectrum of organic acidurias and urea cycle disorders. Part 2: the evolving clinical phenotype

BACKGROUND

The disease course and long-term outcome of patients with organic acidurias (OAD) and urea cycle disorders (UCD) are incompletely understood.

AIMS

To evaluate the complex clinical phenotype of OAD and UCD patients at different ages.

RESULTS

Acquired microcephaly and movement disorders were common in OAD and UCD highlighting that the brain is the major organ involved in these diseases. Cardiomyopathy [methylmalonic (MMA) and propionic aciduria (PA)], prolonged QTc interval (PA), optic nerve atrophy [MMA, isovaleric aciduria (IVA)], pancytopenia (PA), and macrocephaly [glutaric aciduria type 1 (GA1)] were exclusively found in OAD patients, whereas hepatic involvement was more frequent in UCD patients, in particular in argininosuccinate lyase (ASL) deficiency. Chronic renal failure was often found in MMA, with highest frequency in mut(0) patients. Unexpectedly, chronic renal failure was also observed in adolescent and adult patients with GA1 and ASL deficiency. It had a similar frequency in patients with or without a movement disorder suggesting different pathophysiology. Thirteen patients (classic OAD: 3, UCD: 10) died during the study interval, ten of them during the initial metabolic crisis in the newborn period. Male patients with late-onset ornithine transcarbamylase deficiency were presumably overrepresented in the study population.

CONCLUSIONS

Neurologic impairment is common in OAD and UCD, whereas the involvement of other organs (heart, liver, kidneys, eyes) follows a disease-specific pattern. The identification of unexpected chronic renal failure in GA1 and ASL deficiency emphasizes the importance of a systematic follow-up in patients with rare diseases.

Dimethylarginines as biomarkers for the kidney transplant management in methylmalonic aciduria

Methylmalonic aciduria (MMA) is an inborn error of metabolism associated with many complications despite treatment. Chronic renal failure is the most common problem, and patients may eventually require kidney transplant. Therefore, it is worth investigating whether living donor kidney transplant offers a better option than deceased kidney donors; and the value of novel vascular risk biomarkers in the assessment of transplanted MMA patients. We report a case of a 26-year-old man with MMA, who progressed to end-stage renal disease and received kidney transplant from a heterozygous next-of-kin living donor at 20 years of age. Although post-transplant urinary levels of methylmalonic acid decreased, this reduction was lower than previously reported for deceased donors. No episodes of metabolic decompensation were observed after transplantation. During his clinical progress, vascular complications appeared; and finally, pancreatitis was the cause of death. After kidney transplant, we evaluated novel vascular risk factors, such as asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA), which were used as early biomarkers of progression and metabolic management for this transplanted patient. This case report illustrates the disadvantage of transplantation with an allograft from a heterozygous living donor, and the utility of vascular risk biomarkers in renal transplant assessment.

Gastrointestinal dysfunction in autism spectrum disorder: the role of the mitochondria and the enteric microbiome

Autism spectrum disorder (ASD) affects a significant number of individuals worldwide with the prevalence continuing to grow. It is becoming clear that a large subgroup of individuals with ASD demonstrate abnormalities in mitochondrial function as well as gastrointestinal (GI) symptoms. Interestingly, GI disturbances are common in individuals with mitochondrial disorders and have been reported to be highly prevalent in individuals with co-occurring ASD and mitochondrial disease. The majority of individuals with ASD and mitochondrial disorders do not manifest a primary genetic mutation, raising the possibility that their mitochondrial disorder is acquired or, at least, results from a combination of genetic susceptibility interacting with a wide range of environmental triggers. Mitochondria are very sensitive to both endogenous and exogenous environmental stressors such as toxicants, iatrogenic medications, immune activation, and metabolic disturbances. Many of these same environmental stressors have been associated with ASD, suggesting that the mitochondria could be the biological link between environmental stressors and neurometabolic abnormalities associated with ASD. This paper reviews the possible links between GI abnormalities, mitochondria, and ASD. First, we review the link between GI symptoms and abnormalities in mitochondrial function. Second, we review the evidence supporting the notion that environmental stressors linked to ASD can also adversely affect both mitochondria and GI function. Third, we review the evidence that enteric bacteria that are overrepresented in children with ASD, particularly Clostridia spp., produce short-chain fatty acid metabolites that are potentially toxic to the mitochondria. We provide an example of this gut–brain connection by highlighting the propionic acid rodent model of ASD and the clinical evidence that supports this animal model. Lastly, we discuss the potential therapeutic approaches that could be helpful for GI symptoms in ASD and mitochondrial disorders. To this end, this review aims to help better understand the underlying pathophysiology associated with ASD that may be related to concurrent mitochondrial and GI dysfunction.

Proposed guidelines for the diagnosis and management of methylmalonic and propionic acidemia

Methylmalonic and propionic acidemia (MMA/PA) are inborn errors of metabolism characterized by accumulation of propionic acid and/or methylmalonic acid due to deficiency of methylmalonyl-CoA mutase (MUT) or propionyl-CoA carboxylase (PCC). MMA has an estimated incidence of ~ 1: 50,000 and PA of ~ 1:100’000 -150,000. Patients present either shortly after birth with acute deterioration, metabolic acidosis and hyperammonemia or later at any age with a more heterogeneous clinical picture, leading to early death or to severe neurological handicap in many survivors. Mental outcome tends to be worse in PA and late complications include chronic kidney disease almost exclusively in MMA and cardiomyopathy mainly in PA. Except for vitamin B₁₂ responsive forms of MMA the outcome remains poor despite the existence of apparently effective therapy with a low protein diet and carnitine. This may be related to under recognition and delayed diagnosis due to nonspecific clinical presentation and insufficient awareness of health care professionals because of disease rarity.

These guidelines aim to provide a trans-European consensus to guide practitioners, set standards of care and to help to raise awareness. To achieve these goals, the guidelines were developed using the SIGN methodology by having professionals on MMA/PA across twelve European countries and the U.S. gather all the existing evidence, score it according to the SIGN evidence level system and make a series of conclusive statements supported by an associated level of evidence. Although the degree of evidence rarely exceeds level C (evidence from non-analytical studies like case reports and series), the guideline should provide a firm and critical basis to guide practice on both acute and chronic presentations, and to address diagnosis, management, monitoring, outcomes, and psychosocial and ethical issues. Furthermore, these guidelines highlight gaps in knowledge that must be filled by future research. We consider that these guidelines will help to harmonize practice, set common standards and spread good practices, with a positive impact on the outcomes of MMA/PA patients.

Current concepts in organic acidurias: understanding intra- and extracerebral disease manifestation

This review focuses on the pathophysiology of organic acidurias (OADs), in particular, OADs caused by deficient amino acid metabolism. OADs are termed classical if patients present with acute metabolic decompensation and multiorgan dysfunction or cerebral if patients predominantly present with neurological symptoms but without metabolic crises. In both groups, however, the brain is the major target. The high energy demand of the brain, the gate-keeping function of the blood-brain barrier, a high lipid content, vulnerable neuronal subpopulations, and glutamatergic neurotransmission all make the brain particularly vulnerable against mitochondrial dysfunction, oxidative stress, and excitotoxicity. In fact, toxic metabolites in OADs are thought to cause secondary impairment of energy metabolism; some of these toxic metabolites are trapped in the brain. In contrast to cerebral OADs, patients with classical OADs have an increased risk of multiorgan dysfunction. The lack of the anaplerotic propionate pathway, synergistic inhibition of energy metabolism by toxic metabolites, and multiple oxidative phosphorylation (OXPHOS) deficiency may best explain the involvement of organs with a high energy demand. Intriguingly, late-onset organ dysfunction may manifest even under metabolically stable conditions. This might be explained by chronic mitochondrial DNA depletion, increased production of reactive oxygen species, and altered gene expression due to histone modification. In conclusion, pathomechanisms underlying the acute disease manifestation in OADs, with a particular focus on the brain, are partially understood. More work is required to predict the risk and to elucidate the mechanism of late-onset organ dysfunction, extracerebral disease manifestation, and tumorigenesis.

Acute pancreatitis with rapid clinical improvement in a child with isovaleric acidemia

Isovaleric acidemia is a rare branched-chain organic acidemia. The authors describe a 3.5-year-old girl with isovaleric acidemia and acute abdominal pain associated with bilious emesis. Elevated serum amylase and abdominal ultrasonography demonstrating an enlarged and edematous pancreas, along with the presence of peripancreatic exudates, confirmed the presence of acute pancreatitis. The patient recovered quickly with intravenous hydration, pancreatic rest, and administration of intravenous L-carnitine. Pancreatitis should be ruled out in the context of vomiting in any patient with isovaleric acidemia. Conversely, branched-chain organic acidemias should be included in the differential diagnosis of any child with pancreatitis of unknown origin.

Metabolic decompensation in methylmalonic aciduria: which biochemical parameters are discriminative?

Recurrent, life-threatening metabolic decompensations often occur in patients with methylmalonic aciduria (MMAuria). Our study evaluated (impending) metabolic decompensations in these patients aiming to identify the most frequent and reliable clinical and biochemical abnormalities that could be helpful for decision-making on when to start an emergency treatment. Seventy-six unscheduled and 179 regular visits of 10 patients with confirmed MMAuria continuously followed by our metabolic centre between 1975 and 2009 were analysed. The most frequent symptom of an impending acute metabolic decompensation was vomiting (90% of episodes), whereas symptoms of intercurrent infectious disease (29%) or other symptoms (such as food refusal and impaired consciousness) were found less often. Thirty-five biochemical parameters were included in the analysis. Among them, pathological changes of acid-base balance reflecting metabolic acidosis with partial respiratory compensation (decreased pH, pCO(2), standard bicarbonate, and base excess) and elevated ammonia were the most reliable biochemical parameters for the identification of a metabolic decompensation and the estimation of its severity. In contrast, analyses of organic acids, acylcarnitines and carnitine status were less discriminative. In conclusion, careful history taking and identification of suspicious symptoms in combination with a small number of rapidly available biochemical parameters are helpful to differentiate compensated metabolic condition and (impending) metabolic crisis and to decide when to start an emergency treatment.

Endocrine manifestations related to inherited metabolic diseases in adults

Most inborn errors of metabolism (IEM) are recessive, genetically transmitted diseases and are classified into 3 main groups according to their mechanisms: cellular intoxication, energy deficiency, and defects of complex molecules. They can be associated with endocrine manifestations, which may be complications from a previously diagnosed IEM of childhood onset. More rarely, endocrinopathies can signal an IEM in adulthood, which should be suspected when an endocrine disorder is associated with multisystemic involvement (neurological, muscular, hepatic features, etc.). IEM can affect all glands, but diabetes mellitus, thyroid dysfunction and hypogonadism are the most frequent disorders. A single IEM can present with multiple endocrine dysfunctions, especially those involving energy deficiency (respiratory chain defects), and metal (hemochromatosis) and storage disorders (cystinosis). Non-autoimmune diabetes mellitus, thyroid dysfunction and/or goiter and sometimes hypoparathyroidism should steer the diagnosis towards a respiratory chain defect. Hypogonadotropic hypogonadism is frequent in haemochromatosis (often associated with diabetes), whereas primary hypogonadism is reported in Alström disease and cystinosis (both associated with diabetes, the latter also with thyroid dysfunction) and galactosemia. Hypogonadism is also frequent in X-linked adrenoleukodystrophy (with adrenal failure), congenital disorders of glycosylation, and Fabry and glycogen storage diseases (along with thyroid dysfunction in the first 3 and diabetes in the last). This is a new and growing field and is not yet very well recognized in adulthood despite its consequences on growth, bone metabolism and fertility. For this reason, physicians managing adult patients should be aware of these diagnoses.