Evaluation for secondary causes of headache: the role of blood and urine testing.

Most patients presenting for evaluation of headache meet diagnostic criteria for a benign, primary headache disorder based on history and physical examination findings alone. No further testing is needed in such cases. Additional diagnostic evaluation is needed in cases that do not meet criteria for a primary headache disorder or which are associated with unusual or worrisome features. This article will review secondary causes of headache listed in the International Classification of Headache Disorders-II in which blood and urine testing might aid in diagnosis. We offer recommendations for diagnostic evaluation when these disorders are suspected causes of headache.