WHO class-specific equations using height for predicting body weight: crude indicator for dry weight in haemodialysis...

Body weight (BW) might be related to total body water, and the difference between a patient's actual BW and ideal BW (IBW) might be the volume marker. However, there has been no information about the association between IBW and dry weight (DW) in haemodialysis (HD) patients.

First, we analysed the relationship between DW and IBW in 51 HD patients. The IBW was calculated by 21 x Height (Ht)(2). Weight status was analysed by the WHO classification. Second, in 12 436 controls, linear equations using Ht(2) were sought to predict the BW in each sex and WHO class. Third, using these equations, predicted BW (PW) was compared with DW in each WHO class at the initiation and after 1 year in 619 new HD patients, retrospectively.

Among 51 HD patients, 38 were normal weight in whom there was no difference between DW and IBW. In each sex and WHO class of the 12 436 controls, linear equations using Ht(2) were developed to predict BW. These equations were applied to 619 new HD patients. In males, there were no differences between PW and DW in underweight (UW), overweight (OW), obese (OB) and extremely obese (EOB) patients at the initiation of the HD. In females, there were no differences between PW and DW in OW patients. Despite no statistical differences, there were wide ranges of distribution from -6 to 6 kg between PW and DW.

BW had a linear relationship with Ht(2) and might be predictable by the WHO class-specific equation using Ht(2). These equations might be useful as a crude indicator of DW in HD patients.