Endocrine Abstracts

Introduction: In the majority of patients presenting to A&E with hypoglycaemia it is secondary to infection or stress and individuals exhibit a ketogenic response. A minority who first present with hypoglycaemia may have endocrine or metabolic disorders. For this reason a full ‘hypoglycaemia screen’ is undertaken. It is recommended by metbionet that before glucose administration, the following are measured: intermediary metabolites (glucose, b-OHB, free fatty acids, lactate), insulin, cortisol, GH, amino acids and acylcarnitines.

Insulin suppresses lipolysis and ketogenesis, thus in the presence of ketones, it would be expected that insulin should be appropriately suppressed.

Aims: To investigate whether the presence of ketones in unexplained hypoglycaemia is always associated with insulin suppression and whether specific measurement of insulin is required. If not, there is a modest potential cost saving.

Methods: Results were reviewed retrospectively on all patients that presented with unexplained hypoglycaemia over a 6-month period between 2012 and 2013. The nationally accepted metbionet criteria was used for the definition of hypoglycaemia <2.6 mmol/l to select the samples. In addition, similar data from a historical study carried out between March 2006 and May 2008, were included.

Inappropriate insulin at the time of hypoglycaemia was defined as >30 pmol/l.

Results: The study viewed 127 patients with glucose of ≤2.6 mmol/l. Two patients had insulin >30 pmol/l. Of the two patients, one had complex pituitary dysfunction; this patient had very high insulin (60.3 pmol/l) and low B-OHB (0.1 mmol/l). The second patient was a 1-month-old baby with high insulin (34.6 pmol/l) and high B-OHB (2.5 mmol/l); interestingly the plasma amino acids were also low indicating an anabolic (hyperinsulinaemic) state.

Conclusion: The study illustrates that suppressed levels of insulin cannot be inferred from the presence of intermediary metabolites. If insulin was only assayed if ketones are absent, complex and rare disorders may be missed.