Background: Patients attending our A+E department with hypoglycaemia have a number of samples collected including metabolic investigations, growth hormone (GH) and cortisol. Most of these children have an intercurrent illness. There is a paucity of published data examining how cortisol and GH respond to physiological hypoglycaemia.
Aims: To assess if peak levels of GH and cortisol correlate with the degree of hypoglycaemia and to evaluate how many endocrine diagnoses these relatively expensive and frequently performed screens yield.
Methods: We present data from 124, prospective, hypoglycaemia screens performed over 30-months. All patients with a bedside capillary blood glucose of <2.9 mmol/l had a true blood glucose and hypoglycaemia screen. Hypoglycaemia was defined as a true glucose <3.0 mmol/l.
Results: Of 124 patients only 88 had hypoglycaemia (true glucose results ranged from 1.1 to 2.9 mmol/l). We found no correlation between either cortisol or GH and the degree of hypoglycaemia (correlation coefficients 0.021 and 0.020 respectively). This suggests blunting of the normal physiological response of both cortisol and GH to hypoglycaemia, which is classically seen in induced hypoglycaemia during the insulin tolerance test.
We looked more closely at patients in whom either cortisol or GH levels were abnormal. There were 13 children (10%) where the cortisol level was <500 nmol/l. Of these 2 were <300 nmol/l. The lowest cortisol was 149 nmol/l and on subsequent investigation this patient was found to be GH deficient but did not have adrenocortical insufficiency (GH level on hypoglycaemia screen was 15.3 mIU/l). A total of 59/124 (48%) individuals had a GH level of <20 mIU/l, with 14 patients (11%) <10 mIU/l. Other than the patient described above no patient was diagnosed with growth hormone deficiency, though several went on to have further investigations.
Conclusions: Our study questions the value of routinely measuring cortisol and particularly GH when performing a hypoglycaemia screen in children with suspected physiological hypoglycaemia, presenting for the first time. Levels of cortisol and GH are not correlated to the degree of hypoglycaemia and appear to have limited diagnostic value.
05 - 07 Nov 2008
British Society for Paediatric Endocrinology and Diabetes