Assessing treatment adherence is crucial to determine adequacy of mineralocorticoid therapy

Abstract

Background: There is no consensus strategy for mineralocorticoid (MC) therapy titration in patients with primary adrenal insufficiency (PAI). W e aim to measure serum fludrocortisone (sFC) and urine fludrocortisone (uFC) levels and to determine their utility, alongside clinical/biochemical variables and treatment adherence to guide MC replacement dose titration. Methods: Multi-centre, observational, cross-sectional study on 41 patients with PAI on MC replacement therapy. sFC and uFC levels (measured by liquid chr omatography-tandem mass spectrometry), plasma renin concentration (PRC), electrolytes (Na+, K+), mean arterial blood pressure (MAP), total daily glucocorticoid (dGC) and MC (dMC) dose, and assessment of treatment adherence were incorporated into statis tical models. Results: We observed a close relationship between sFC and uFC ( r = 0.434, P = 0.005) and between sFC and the time from the last fludrocortisone dose ( r = −0.355, P = 0.023). Total dMC dose was related to dGC dose ( r = 0.556, P < 0.001), K+ (r = −0.388, P = 0.013) as well as sFC (r = 0.356, P = 0.022) and uFC (r = 0.531, P < 0.001). PRC was related to Na+ (r = 0.517, P < 0.001) and MAP (r = −0.427, P = 0.006), but not to MC dose, sFC or uFC. Regression analyses did not support a role for sFC, uFC or PRC measurements and confirmed K+ (B = −44.593, P = 0.005) as the most important variable to guide dMC titration. Of the patients, 32% were non-adherent with replacem ent therapy. When adherence was inserted into the regression model, it was the on ly factor affecting dMC. Conclusions: sFC and uFC levels are not helpful in guiding dMC titration. T reatment adherence impacts on clinical variables used to assess MC replacement and should be included as part of routine care in patients with PAI.

Keywords

• mineralocorticoids
• glucocorticoids
• congenital adrenal hyperplasia
• addison’s disease
• renin