A hyperglycaemic hyperosmolar state in a young child: diagnostic insights from a quantitative analysis
From the 1Hospital das Clinicas, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil, 2Department of Critical Care Medicine, Hospital for Sick Children and Departments of Anaesthesia and Medicine, University of Toronto, and 3Division of Nephrology, St Michael's Hospital, University of Toronto, Toronto, Canada, and 4Division of Nephrology and Department of Medicine, Stellenbosch University, Cape Town, South Africa
Address correspondence to Professor M.L. Halperin, Professor of Medicine, University of Toronto, St Michael's Hospital Annex, Lab #1, Research Wing, 38 Shuter Street, Toronto Ontario, M5B 1A6, Canada. email: mitchell.halperin{at}utoronto.ca
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Abstract |
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This teaching exercise demonstrates how the application of principles of physiology can identify the cause of a severe degree of hyperglycaemia (plasma glucose concentration 80 mmol/l) in a very young patient with newly diagnosed diabetes mellitus, determine whether the patient has diabetic ketoacidosis, and highlight the potential risks for this patient on admission and during initial therapy. A consultation with Professor McCance was sought to determine whether this patient had an unusual degree of ‘insulin resistance’. There were also uncertainties regarding the acid–base diagnosis. The patient did not appear to have an important degree of metabolic acidosis as judged from his pH of 7.39 and plasma bicarbonate concentration of 20 mmol/l in arterial blood; hence the diagnostic impression was that he had a hyperglycaemic hyperosmolar state. However, his plasma anion gap was significantly elevated, and remained so for 60 h, despite the administration of insulin. Issues in management concerning the basis for this severe degree of hyperglycaemia and how to minimize the risk of developing cerebral oedema are addressed. The missing links in this interesting story emerge during a discussion between the medical team and their mentor, Professor McCance.