CASE REPORT

An unusual case of hyponatraemia in diabetic ketoacidosis

P J Twomey¹, J Cordle¹, D R Pledger¹ and Y Miao²

¹ Department of Clinical Biochemistry, The Ipswich Hospital, Heath Road, Ipswich IP4 5PD, UK
² Department of Gastroenterology and General Medicine, The Ipswich Hospital

Correspondence to:
Correspondence to:
Dr P J Twomey
Department of Clinical Biochemistry, The Ipswich Hospital, Heath Road, Ipswich IP4 5PD, UK; PatTwomey{at}doctors.org.uk

This report outlines a case of diabetic ketoacidosis associated hyponatraemia in an 18 year old woman with type 1 diabetes who presented to the accident and emergency department and was quickly admitted to the intensive treatment unit. Causes of hyponatraemia include sodium depletion, pseudohyponatraemia, and extracellular hypertonicity. Hypertonicity secondary to hyperglycaemia is thought to be the major cause of hyponatraemia in diabetic ketoacidosis. Indirect and direct sodium measurements were performed until the glucose concentration stabilised. The large difference between the presenting sodium concentrations is consistent with pseudohyponatraemia. However, the causes of pseudohyponatraemia (large increases in total protein, triglyceride, and cholesterol concentrations) were excluded. Analytical error should always be considered when the laboratory results do not agree with the clinical picture. Sometimes, however, even after excluding all known effects, the cause may remain unexplained, as in this case.

Abbreviations: DKA, diabetic ketoacidosis; ISE, ion specific electrode

Keywords: indirect selective electrode; diabetes; direct selective electrode; hyponatraemia; pseudohyponatraemia

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This article has been cited by other articles:

• Al-Musheifri, A., Jones, G. R D (2008). Glucose interference in direct ion-sensitive electrode sodium measurements. Ann Clin Biochem 45: 530-532 [Abstract] [Full Text]  
• Jones, B J, Twomey, P J (2008). Relationship of the absolute difference between direct and indirect ion selective electrode measurement of serum sodium and the total protein concentration. J. Clin. Pathol. 61: 645-647 [Abstract] [Full Text]