A low-cost and simple method has been developed for the preparation of human or animal protein-based adsorbents for use in the thyroid hormone uptake test. A combination of sodium sulphate precipitation and glutaraldehyde polymerisation of pooled whole serum or purified albumin preparations was employed to yield a fine solid-phase suspension which eliminates the need for capping and rotating assay tubes. Results for 107 samples obtained by this method correlated well with those obtained by use of a commercial kit.