[Diagnostic studies in patients suspected of having an immunodeficiency disorder]

Knowledge of the normal structure and function of the human immunological defence system, as well as of its disorders has increased considerably during recent decades. On the basis of this an operational classification of immunodeficiency diseases can be made. In this contribution patterns of infection and associated symptoms, characterizing the different types of primary immunodeficiency diseases, are described. Also a protocol for the assessment of the immunological competence is proposed. A characteristic feature of this protocol is a graduation in stages of tests with increasing complexity. The aim of such a grouping is to tackle the presenting problem in a systematic manner, as well as to avoid needless burden to the patient and excessive costs. However, this does not obviate the need for expert knowledge of and experience with immunodeficiency diseases, in order to be able to ask for the appropriate laboratory tests, to judge the results of these tests and to appreciate their relevance for the clinical problem.