Testing of Adrenal Axis Function in Patients With Combined Pituitary Hormone Deficiency Caused by PROP1 Mutation

Abstract

Background: The mechanism of adrenal axis deterioration in PROP1 mutation remains uncertain and challenging. Aim: The aim of the project was to investigate the adrenal axis function in patients with combined pituitary function deficiency and PROP1 mutation. Methods: We performed the corticotrophin (CRH) stimulation test in 15 patients ((8W/7M) with confirmed CPHD due to the PROP1 mutation. 9/15 were familial cases from four families. Time of observation (ToO) was calculated since the first pituitary axis/ACTH insufficiency has occurred. The results were reported in the group with confirmed Adrenal Insufficiency (AI) and without AI defined as cortisol >18 ug/dl at any point during CRH test. ACTH is reported in pg/ml and cortisol in ug/dl, time of test is given in minutes (0‘, 15’,30’,45’,60’,120’). Results: The mean age of the group was 40,6 ± 12,1 years with mean 34,7 ± 10,3 years of CPHD observation (range 18 – 54 years). The In 5/15 the cortisol response met the criteria excluding AI. Among siblings there were patients both with/without AI. Both subgroups had similar ToO (without AI 35,6 ± 10,0 years vs 34,2 ± 10,3 years with AI). Mean time of AI duration was 15,0 ± 9,3 years. In the group of 5 patients without AI the mean morning cortisol was 12,48 ± 4,31 and ACTH was 31,26 ± 5,43. The mean maximal concentration of cortisol and ACTH were 24,94 ± 3,6 and 123,6 ± 39,9 respectively; Mean increase of cortisol was 12,46 ±4,04 and 92,34±34,48 for ACTH. In 10 patients with AI the mean morning cortisol was 3,33±1,39 and ACTH 22,71±6,75. The mean maximal concentration of cortisol and ACTH were 10,15±4,47 and 97,05 ± 59,15 respectively; Mean increase of cortisol was 6,83 ± 3,41 and 74,35 ± 53,72 for ACTH. For two patients high ACTH increase from 36,7 to 260 and from 28,65 to 112,0 was observed. Analysis of cortisol and ACTH response in both groups revealed that in group without AI the time of peak of ACTH was observed in 15’ (2/5) and 30’ (3/5) vs. in 15’(3/10), 30’(6/10) and 45’ in group with AI. The peak cortisol was observed in 30’, 45’ and 60’ (3/5) in group without AI vs 60’(6/10) or 120’ (4/10) in AI group. The mean maximal increase of ACTH was by 4,09±1,46 and 4,12±1,58 in AI group vs no AI group respectively. Conclusions: In patients with PROP1 mutation the adrenal axis can deteriorate long after other axis insufficiencies, however there are patients with no adrenal insufficiency even during lifelong observation. There is no specific order of deterioration even among affected siblings. In the vast majority of patients independently of cortisol increase there is ACTH response after CRH. Further studies on the pituitary function deterioration in patients with PROP1 mutation should be carried out to understand better the underlying mechanism and to set up the diagnostic timing and procedures.