Protein markers of nutrition status as related to sex and age.

We assessed age- and sex-related variation in those proteins commonly measured to evaluate protein catabolic losses in patients in acute care. We determined concentrations of iron and iron-binding capacity, transferrin, albumin, prealbumin, and retinol-binding protein in sera from 158 healthy blood donors and 48 hospitalized patients, then grouped the data according to age (by decade) and sex. There was no significant variation in either category. For the total nondiseased population the concentrations of three proteins (means SD, and range) were: transferrin, 2760, 510, 1740-3780 mg/L (population CV 18.5%); prealbumin, 296, 49, 200-390 mg/L (CV 16.6%); retinol-binding protein, 60, 127, 35-85 mg/L (CV 21.2%). Prealbumin and retinol-binding protein concentrations were highly correlated (r = 0.803). Because prealbumin can be easily monitored and its assay is subject to few interferences, we conclude that determination of prealbumin is suitable for assessing the existence and severity of nutritional metabolic deficits.