Endocrine Abstracts

Dynamic pituitary testing is a time consuming and high cost investigation. For effective use of this procedure a close audit of the effectiveness and outcome of testing is required. At UCH we have developed a streamlined nurse led service with medical supervision and we now present an audit of 1 year of testing.

Forty-one patients underwent pituitary function testing for growth hormone (GH) and ACTH during 2006. Referral source was from the endocrine team (24), the neurosurgical team (15) and paediatrics for end of growth assessment (2). Patients’ age ranged between 17 and 78 years (mean=42.2; S.D.=16.08). About 25 (61%) patients underwent insulin tolerance test (ITT) and 16 (39%) glucagon stimulation test. All patients had adequate stress on an ITT with glucose <2.2 mmol/l and hypoglycaemic symptoms. Hypoglycaemia was reversed orally for most patients within 10–15 min; only 5 patients required intravenous infusion of 10% glucose due to prolonged hypoglycaemia.

With regard to the ACTH axis, 11 (26.8%) patients previously established ACTH deficiency and were on cortisol replacement. Of the remaining 30 (73.2%) patients, 9 were newly diagnosed with ACTH deficiency. Hydrocortisone was administered to patients with established ACTH deficiency at the end of the test (or during the test where prolonged hypoglycaemic symptoms occurred).

With regard to the GH axis, 30 (68%) patients were found to have severe GH deficiency (GHD) as indicated by a peak GH of <9 mIU/l. A strong correlation was found between peak GH and IGF1 levels (r=0.516; P=0.001). AGHDA QoL score ranged between 0/25 to 23/25 (mean=14/25; S.D.=7.4). No correlation was found between AGHDA QoL score and peak GH or IGF1 levels. Of the 30 patients diagnosed with GHD, 22 satisfied the NICE criteria on adult GH deficiency (NICE, 2003) and were started on GH replacement. Three patients younger than 25 years of age had peak GH <9 mU/l and AGHDA QoL score <11; they were started on GH for peak bone mass achievement and will be re-assessed at 25 years.

We conclude, in a unit focussed mainly on GH deficiency, ~50% of patients undergoing dynamic pituitary testing finally require GH replacement and that IGF1 measurements may be a useful alternative guide in some cases.