Purpose of reviewAlthough mycophenolate mofetil (MMF) has been used successfully to treat a myriad of autoimmune diseases, its complex pharmacokinetics make it difficult to determine the true drug exposure for an individual patient. This review summarizes the body of literature focused on the gold standard measurement of the area under the curve (AUC) of mycophenolic acid (MPA), the active metabolite of MMF. Recent findingsFixed dosing of MMF leads to highly variable drug exposure. Retrospective series have reported improved clinical outcomes when a minimum AUC value from 0 to 12 h (AUC 0-12h ) !30 mg h/l is achieved. MPA levels are affected by various drug interactions, hypoalbuminemia, and renal insufficiency and the measurement of free rather than total MPA levels is prudent in some situations. A limited number of studies employing prospective dose adjustment of MMF based on AUC 0-12h measurements have yielded mixed results. SummaryGiven the wide range of MPA AUC encountered in autoimmune diseases, dose adjustments of MMF based on AUC rather than fixed dosing of MMF should be considered in both clinical practice and clinical trials. Limited sampling strategies have been proposed to improve clinical feasibility of measurements, but a standard is yet to be defined.

Objective Levels of tissue iron contribute to determining diabetes risk, but little is known about the effects of higher iron levels on weight, nor on the interaction of weight and iron overload on diabetes risk. We therefore examined the effect of iron on body mass index and diabetes in individuals with iron overload from hereditary hemochromatosis (HH), compared to non-HH siblings and historical controls. Methods Chart reviews were performed on a cohort of adults (age ≥40, N=101) with the common C282Y/C282Y HFE genotype, compared to wild type siblings (N=32) and comparable NHANES cohorts, with respect to body mass index and diabetes status. Results Males with HH have lower body mass index (BMI) than control siblings. Females had a trend toward decreased BMI that was not significant, possibly related to decreased degrees of iron overload. In both males and females, increased rates of diabetes were seen, especially in the overweight or obese. Conclusions High tissue iron levels may be both pro- and anti-diabetic. The prevalence of obesity and diabetes in HH is likely dependent upon the degree of iron overload, caloric intake, and other genetic and environmental factors, contributing to the observed heterogeneity in the frequency of disease-related morbidities in HH.

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