Pura M.,National Institute of Endocrinology and Diabetology |
Kreze A.,Bulovka Faculty Hospital |
Kento P.,National Institute of Endocrinology and Diabetology |
Vauga P.,National Institute of Endocrinology and Diabetology
Experimental and Clinical Endocrinology and Diabetes | Year: 2010
Background: The validity of low-dose 1g cosyntropin test (LDT) is reported mainly for the assessment of secondary adrenocortical insufficiency (AI). Likewise the hypothalamic-pituitary disorders, early diagnosis of the initial or partial stages of primary AI has an important role. Objective: The aim of study was to: 1) establish the normal cut-off level at which the stimulated plasma cortisol (FP) in LDT excludes primary AI; 2) compare the results in elderly subjects to those in younger ones; 3) compare the results between normal and obese subjects; and 4) verify the established cut-off values on the sample of patients suspected to have primary AI. Subjects and Methods: 110 subjects (99 women and 11 men, aged 1980 years, mean 46.2±16.1 years, without suspicion for impairment of the hypothalamo-pituitary-adrenal axis were recruited to undergo the LDT in standard conditions. Control group consists of 30 patients (22 women and 8 men, aged 758 years, mean 38.4±10.6 years) evaluated in whom for suspicion of primary AI as suggested by LDT was confirmed by supplemental investigations (elevated ACTH levels, positive autoantibodies against 21-hydroxylase, mutational analysis of corresponding genes). Results: The mean peak FP level at 30min (FP30) of the subjects was 675±85nmol/L (95% CI=659 to 691nmol/L), thus reference values expressed as mean±2 SD were 505845nmol/L. There was a significant negative correlation between basal FP values (FP0) (434±105nmol/L) and the absolute FP incremental (FP1) response varying from 52 to 553nmol/L (median 230nmol/L) (r=0.71; P<0.001). FP30 was higher in elderly subjects (n=27) in comparison to younger subjects (n=25) (689±88nmol/L vs. 642±63nmol/L, u=2.11, P<0.05) due to higher FP1 (274±116nmol/L vs. 175±112nmol/L; u=4.02, P<0.01); FP30 levels in obese subjects (n=27) did not differ from those with normal BMI (n=33) (694±100nmol/L vs. 667±65nmol/L, u=1.31, P>0.05). We did not find any correlation between body weight or body surface area and FP0, FP30 or FP1. Post-stimulation FP30 levels in the control group varied from 0 to 354nmol/L with median 64nmol/L (25th percentile 10nmol/L; 75 th percentile 165nmol/L) and were entirely distinctive from those of the subjects without adrenal impairment (P<0.001). Conclusions: Taking the mean 2 SD result as a threshold, FP value of 500nmol/L can be consider as cut-off at 30min in the LDT for defining the intact adrenocortical function, independently of age and body weight, body surface area. © J. A. Barth Verlag in Georg Thieme Verlag KG Stuttgart - New York.