NO American can read The Gift Relationship: From Human Blood to Social Policy, by Richard M. Titmuss (Pantheon, $6.95) without shame. We are generally aware that American health services are in bad shape. They are enormously expensive, both absolutely and as a share of Gross National Product; they are inequitably distributed, both geographically and socially; they are not terribly effective in improving health; they are very badly coordinated—if indeed they can be said to be coordinated at all; they are difficult of access and comprehension.