To the Editor.—
Wong and Freier (1982;247:75) have presented an algorithm for use of laboratory tests in the differential diagnosis of hypercalcemia that fails to use valuable historical information until step 4 of their scheme. Decision 4 requires the answer to the question concerning the patient's use of drugs that could cause hypercalcemia. I suggest that this basic piece of historical data be used in the algorithm at a much earlier decision point. Evaluation of the patient's drug history at an earlier point could save the patient, whose condition is being evaluated by this decision pathway, the pain and risks of multiple venipunctures and the costs of the concomitant laboratory tests. Rufus of Ephesus (c 100 AD) pointed out that the history is an invaluable part of the diagnostic evaluation. I see no reason to ignore historical data until well into the workup of hypercalcemia.