Evaluation of random plasma cortisol and the low dose corticotropin test as indicators of adrenal secretory capacity in critically ill patients: A prospective study

It is unclear whether a random plasma cortisol measurement and the corticotropin (ACTH) test adequately reflect glucocorticoid secretory capacity in critical illness. This study aimed to determine whether these tests provide information representative of the 24 hour period. Plasma cortisol was measured hourly for 24 hours in 21 critically ill septic patients followed by a corticotropin test with 1 μ g dose administered intravenously. Serum and urine were analysed for ACTH and free cortisol respectively. Marked hourly variability in plasma cortisol was evident (coefficient of variation 8-30%) with no demonstrable circadian rhythm. The individual mean plasma cortisol concentrations ranged from 286 59 nmol/l to 796 &PLUSMN; 83 nmol/l. The 24 hour mean plasma cortisol was strongly correlated with both random plasma cortisol (r(2) 0.9, P< 0.0001) and the cortisol response to corticotropin (r(2) 0.72, P< 0.001). Only nine percent of patients increased their plasma cortisol by 250 nmol/l after corticotropin (euadrenal response). However, 35% of non-responders had spontaneous hourly rises > 250 nmol/l thus highlighting the limitations of a single point corticotropin test. Urinary free cortisol was elevated (865&PLUSMN; 937 nmol) in both corticotropin responders and non-responders suggesting elevated plasma free cortisol. No significant relationship was demonstrable between plasma cortisol and ACTH. We conclude that although random cortisol measurements and the low dose corticotropin tests reliably reflect the 24 hour mean cortisol in critical illness, they do not take into account the pulsatile nature of cortisol secretion. Consequently, there is the potential for erroneous conclusions about adrenal function based on a single measurement. We suggest that caution be exercised when drawing conclusions on the adequacy of adrenal function based on a single random plasma cortisol or the corticotropin test.

Doubling daily inhaled corticosteroid dose is ineffective in mild to moderately severe attacks of asthma in adults

Background: Asthma guidelines recommend increasing or doubling inhaled corticosteroid (ICS) dose to treat mild and moderate exacerbations of asthma in adults. Aim: To: (i) compare the effectiveness of doubling existing daily ICS dose (fluticasone) with maintaining usual ICS dose and usual daily ICS dose accompanied by oral steroids (OS) (dexamethasone) during mild and moderately severe exacerbations of asthma in adults; (ii) examine determinants of success and failure; and (iii) compare side-effect profiles. Methods: A randomized, double-blind, placebo-controlled (double-dummy), triple crossover trial. Participants acted as their own control. Outcome measures included treatment success/failure, peak expiratory flow (PEF) after 7 days therapy or at treatment failure, and side-effects. Results: From 22 participants (nine males and 13 females), 18 pairs of data were available for maintaining usual ICS versus doubling ICS and doubling ICS versus OS, and 19 for maintaining usual ICS versus OS. Median (fifth-95th percentile) age was 46.5 (32-64) years and forced expiratory volume in one second (FEV1) 73% (29-97%) predicted. The outcome after doubling ICS was not superior to maintaining usual ICS, with 11 (61%) failures in both arms (P = 0.66). OS, with only 5 (26%) failures, was superior to maintaining usual ICS with 12 (63%) failures (P = 0.04), and to doubling ICS with 5 (28%) versus 11 (61%) failures (P = 0.07). Median PEF (as percentage of run-in best) at end-points were 90.5% (57.1-177.1) for OS, 78.3% (39.5-103.1) for maintaining usual ICS and 77.9 (27.7-110.3) for doubling ICS. Neither gender nor PEF at exacerbation were predictive of failure. Although doubling ICS was not an effective therapy overall, ICS dose at exacerbation were predictive of success in the doubling ICS arm (P = 0.04). Treatment failures when doubling daily ICS dose were more common if achieved fluticasone dose was less than 2000 mu g (three of 11, 73%) compared to 2000 mu g or greater (eight of eight, 37.5%). Increasing age and the presence of an upper respiratory tract infection (URTI) were predictive of failure with OS. Side-effects were more commonly reported with OS (52.6%) than doubling ICS (42.1%) or maintaining usual ICS (19.1%) with the most common being mood changes (36.8%), sleep disturbance (31.6%) and changes in appetite (26.3%). Conclusions: Doubling daily ICS dose per se is not effective for the treatment of mild to moderately severe exacerbations of asthma in adults. Success may depend on achieved ICS dose. Oral steroids are effective, but side-effects are common. A review of current guidelines may be warranted.