Protein-calorie malnutrition is associated with poor prognosis in chronic liver disease, but reliable assessment is hampered by changes in body water. We prospectively evaluated the effect of fluid retention on bioelectrical impedance analysis (BIA) as a simple method for the estimation of body cell mass (BCM(BIA)) in 41 patients with cirrhosis (n = 20 with ascites; n = 21 without ascites) using total body potassium counting (BCM(TBP)) as a reference method. Arm muscle area and creatinine-derived lean body mass were compared with total body potassium data. In patients total body potassium was 24.4% lower than in controls and this loss was more severe in patients with ascites (-34.1%; P<.01). BCM(BIA) and BCM(TBP) were closely correlated in controls (r(2) =.87, P<.0001), patients without ascites (r(2) =.94, P <.0001) and patients with ascites (r(2) =.56, P<.0001). Removal of 6.2 +/- 3 L of ascites had only minor effects on BCM(BIA) (deviation of -0.18 kg/L ascites). Limits of agreement between both methods were wider in patients with ascites than in patients without (6.2 vs. 4.2 kg). In patients without ascites arm muscle area (r(2) =.64; P<.001) and lean body mass (r(2) =.55; P<.001) correlated significantly with total body potassium, but not in patients with ascites. For assessment of protein malnutrition in patients with cirrhosis, body cell mass determination by use of BIA offers a considerable advantage over other widely available but less accurate methods like anthropometry or the creatinine approach. Despite some limitations in patients with ascites, BIA is a reliable bedside tool for the determination of body cell mass in cirrhotic patients with and without ascites.

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Cushing's syndrome (CS) is associated with low fat-free mass, but it is unclear whether hypercortisolism causes a loss of whole body protein. Body composition was studied prospectively in 15 patients with untreated CS (n = 14 pituitary adenoma; n = 1 adrenal adenoma), in 15 nonobese healthy controls, and in 15 weight-matched obese controls by 3 different methods: total body potassium counting (TBP), bioelectrical impedance analysis (BIA), and anthropometry. In 6 patients, body composition was studied before and within 6 months after pituitary surgery. In CS patients and weight-matched controls, body weight and total body fat were significantly higher than in nonobese controls. In CS patients, TBP was 18.4% lower than predicted, whereas in weight-matched controls TBP was 7.1% higher than predicted. As compared with nonobese and weight-matched controls, in CS patients TBP indicated a significant loss of body cell mass (BCM) of -20.2 and -21.1%, respectively. A significantly reduced arm muscle area of -21.3% compared with weight-matched controls also indicated a loss of whole body protein. In CS, however, BIA overestimated BCM when compared with TBP by +18% and agreement between BIA and TBP in the individual patient was poor (limits of agreement plus minus 27.6%), indicating the invalidity of standard BIA equations in this population. Measurements performed before and 6 months after successful pituitary surgery demonstrated a significant loss of body weight (-11%) and body fat (-33%), but BCM and muscle mass remained on a constant low level. In conclusion, this study shows that, in patients with CS, a significantly reduced BCM indicates a true protein loss. The second interesting finding is that in the early recovery after successful treatment of hypercortisolism patients lose body fat without gaining BCM or muscle mass.

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