Estimation of renal function in patients with eating disorders.

ABSTRACT

BACKGROUND: Renal function could be evaluated with different equations such as Cockcroft-Gault formula (C-G), Mayo Clinic Quadratic (MAYO) and four MDRD variables. Clinical application of different formulae in conditions with severe energy restriction or in obese subjects is still a matter of investigation. METHOD: Renal function of 55 anorexia nervosa (AN) and 44 bulimia nervosa (BN) patients was evaluated with C-G formula for creatinine clearance calculation, and glomerular filtration rate (GFR) was estimated with MAYO and MDRD equations. RESULTS: BN group was older and had higher weight, body mass index (BMI), body surface area than AN subjects; however, their mean BMI was in the normal range. AN group had better renal function than BN one when it was evaluated with MAYO and MDRD; on the contrary, it was worse when it was calculated with C-G. The results obtained from the three formulae were poorly correlated and Bland-Altman analysis confirmed that the results of the three formulae were not in agreement. DISCUSSION: C-G is inaccurate when it is applied to obese or cachectic subjects. MDRD underestimates renal function in normal-high GFR. MAYO seems to be a good alternative to the other equations leading to correct classification of patients; therefore, it should be used to diagnose eating disorder subjects as renal insufficient.