Investigation of the child with an acute metabolic disorder

Pediatric non-diabetic ketoacidosis: a case-series report

BACKGROUND

This study is to explore the clinical characteristics, laboratory diagnosis, and treatment outcomes in pediatric patients with non-diabetic ketoacidosis.

METHODS

Retrospective patient chart review was performed between March 2009 to March 2015. Cases were included if they met the selection criteria for non-diabetic ketoacidosis, which were: 1) Age ≤ 18 years; 2) urine ketone positive ++ or >8.0 mmol/L; 3) blood ketone >3.1 mmol/L; 4) acidosis (pH < 7.3) and/or HCO₃ < 15 mmol/L; 5) random blood glucose level < 11.1 mmol/L. Patients who met the criteria 1, 4, 5, plus either 2 or 3, were defined as non-diabetic ketoacidosis and were included in the report.

RESULTS

Five patients with 7 episodes of non-diabetic ketoacidosis were identified. They all presented with dehydration, poor appetite, and Kussmaul breathing. Patients treated with insulin plus glucose supplementation had a quicker recovery from acidosis, in comparison to those treated with bicarbonate infusion and continuous renal replacement therapy. Two patients treated with bicarbonate infusion developed transient coma and seizures during the treatment.

CONCLUSION

Despite normal or low blood glucose levels, patients with non-diabetic ketoacidosis should receive insulin administration with glucose supplementation to correct ketoacidosis.

Neonatal hypoglycemia

Glucose is essential for cerebral metabolism. Unsurprisingly therefore, hypoglycemia may result in encephalopathy. Knowledge of the homeostatic mechanisms that maintain blood glucose concentrations within a tight range is the key for diagnosis and appropriate management of hypoglycemia. Neonatal hypoglycemia can be transient and is commonly observed in at-risk infants. A wide range of rare endocrine and metabolic disorders can present with neonatal hypoglycemia, of which congenital hyperinsulinism is responsible for the most severe form of hypoglycemia. Collection of appropriate blood samples for hormones and intermediary metabolites during an episode of hypoglycemia is critical for diagnosis and appropriate management. Prompt diagnosis with aggressive early intervention remains the mainstay of treatment to avert irreversible brain damage.

The molecular mechanisms, diagnosis and management of congenital hyperinsulinism

Congenital hyperinsulinism (CHI) is the result of unregulated insulin secretion from the pancreatic β-cells leading to severe hypoglycaemia. In these patients it is important to make an accurate diagnosis and initiate the appropriate management so as to avoid hypoglycemic episodes and prevent the potentially associated complications like epilepsy, neurological impairment and cerebral palsy. At a genetic level abnormalities in eight different genes (ABCC8, KCNJ11, GLUD1, GCK, HADH, SLC16A1, HNF4A and UCP2) have been reported with CHI. Loss of function mutations in ABCC8/KCNJ11 lead to the most severe forms of CHI which are usually medically unresponsive. At a histological level there are two major subgroups, diffuse and focal, each with a different genetic etiology. The focal form is sporadic in inheritance and is localized to a small region of the pancreas whereas the diffuse form is inherited in an autosomal recessive (or dominant) manner. Imaging using a specialized positron emission tomography scan with the isotope fluroine-18 L-3, 4-dihydroxyphenyalanine (18F-DOPA-PET-CT) is used to accurately locate the focal lesion pre-operatively and if removed can cure the patient from hypoglycemia. Understanding the molecular mechanisms, the histological basis, improvements in imaging modalities and surgical techniques have all improved the management of patients with CHI.

From genetics to genomics of epilepsy

The introduction of DNA microarrays and DNA sequencing technologies in medical genetics and diagnostics has been a challenge that has significantly transformed medical practice and patient management. Because of the great advancements in molecular genetics and the development of simple laboratory technology to identify the mutations in the causative genes, also the diagnostic approach to epilepsy has significantly changed. However, the clinical use of molecular cytogenetics and high-throughput DNA sequencing technologies, which are able to test an entire genome for genetic variants that are associated with the disease, is preparing a further revolution in the near future. Molecular Karyotype and Next-Generation Sequencing have the potential to identify causative genes or loci also in sporadic or non-familial epilepsy cases and may well represent the transition from a genetic to a genomic approach to epilepsy.

Severe hyperammonaemia in adults not explained by liver disease

Ammonia is produced continuously in the body. It crosses the blood-brain barrier readily and at increased concentration it is toxic to the brain. A highly integrated system protects against this: ammonia produced during metabolism is detoxified temporarily by incorporation into the non-toxic amino acid glutamine. This is transported safely in the circulation to the small intestine, where ammonia is released, carried directly to the liver in the portal blood, converted to non-toxic urea and finally excreted in urine. As a result, plasma concentrations of ammonia in the systemic circulation are normally very low (<40 μmol/L). Hyperammonaemia develops if the urea cycle cannot control the ammonia load. This occurs when the load is excessive, portal blood from the intestines bypasses the liver and/or the urea cycle functions poorly. By far, the commonest cause is liver damage. This review focuses on other causes in adults. Because they are much less common, the diagnosis may be missed or delayed, with disastrous consequences. There is effective treatment for most of them, but it must be instituted promptly to avoid fatality or long-term neurological damage. Of particular concern are unsuspected inherited defects of the urea cycle and fatty acid oxidation presenting with catastrophic illness in previously normal individuals. Early identification of the problem is the challenge.