Timed urine collections are difficult to use in clinical practice owing to inaccurate collections making calculations of the 24-h albumin or protein excretion questionable. One of our goals was to assess the 'correction' of urinary albumin and (or) protein excretion by dividing these by either the creatinine concentration or the term, (specific gravity-1)x100 1 1Note that the term, (SG-1)x100 increases with the increasing concentration of all dissolved solids. Because (1-SG)x100 is dimensionless, we called (SG-1)x100 'SG units', i.e. SGU.