Urinary 6‐hydroxymethylpterin levels accurately monitor response to chemotherapy in acute lymphoblastic leukemia

: In our earlier study it was shown that patients with various types of cancer excrete three- to 20-fold higher levels of urinary 6-hydroxymethylpterin as compared to patients with nonmalignant diseases or normal volunteers. In the present study urinary 6-hydroxymethylpterin levels have been measured as an index of disease status in acute myeloblastic leukemic patients on antileukemic drugs. The daily excretory pterin levels and the values of respective blast counts have been graphically presented for four cases with the chemotherapeutic regimens. Remission of the disease was marked by a rapid drop in the urinary 6-hydroxymethylpterin levels and correlated very well with the percentage of blasts. In another study the percentage of blasts and the urinary 6-hydroxymethylpterin were determined simultaneously in four patients undergoing chemotherapy. The data conclusively show that the simple noninvasive determination of urinary 6-hydroxymethylpterin levels accurately and rapidly reflects the status of the disease under treatment and could conveniently be employed as a suitable index for monitoring the effect of chemotherapy as well as the condition of the residual extramedullary leukemic infiltration.