The CuSO4 gravimetric test has been the method of choice for the primary Hb screening of potential blood donors for many years.
Although very anemic donors can, on occasion, pass the CuSO4 test [4], There are reports suggesting that the CuSO4 method tends to give inappropriate failures also.
A significant number of such failed donors can be recovered with revised Hb range or if an alternative screening method is applied [5].