**Question:** Lactic acidosis is a side effect of:

A. Metformin
B. Insulin
C. Glucocorticoids
D. L-asparaginase

**Core Concept:** Lactic acidosis is a severe, life-threatening complication characterized by elevated blood lactate levels and acidosis. It can be caused by various factors, including medications.

**Why the Correct Answer is Right:** D-Dimer test is an important diagnostic tool used to evaluate suspected deep vein thrombosis and pulmonary embolism. However, when D-Dimer levels are elevated inappropriately, it may indicate a false positive result due to the use of D-Dimer testing itself. L-asparaginase, an enzyme used in the treatment of certain cancers like acute lymphoblastic leukemia, can lead to hypercoagulability and subsequent activation of the coagulation cascade. This can result in widespread clot formation and impaired fibrinolysis, leading to D-Dimer elevation and potentially false positive results in diagnostic tests.

**Why Each Wrong Option is Incorrect:**

A. Metformin, an oral hypoglycemic agent used in diabetes mellitus treatment, does not cause lactic acidosis as a side effect.
B. Insulin, a hormone used for diabetes mellitus treatment, does not cause lactic acidosis either.
C. Glucocorticoids, a class of steroid hormones used in various medical conditions, do not typically cause lactic acidosis as a side effect.

**Why the Correct Answer is Right:**

Lactic acidosis is a rare but severe side effect associated with the use of L-asparaginase-containing chemotherapy regimens. It is usually observed when D-Dimer levels are elevated and associated with a negative D-Dimer test result, indicating a false positive due to L-asparaginase use. This knowledge is essential for clinicians to recognize the potential complication and avoid misinterpretation of diagnostic test results.

**Why Each Wrong Option is Incorrect:**

A. Metformin, an oral hypoglycemic agent, does not cause lactic acidosis as a side effect.
B. Insulin, a hormone used for diabetes mellitus treatment, does not cause lactic acidosis either.
C. Glucocorticoids, a class of steroid hormones used in various medical conditions, do not typically cause lactic acidosis as a side effect.

**Clinical Pearl:** When encountering a patient with elevated D-Dimer levels and a negative D-Dimer test result, it is crucial to consider the possibility of L-asparaginase-induced lactic acidosis. A high index of suspicion and prompt discontinuation of the causative medication can prevent this severe complication and improve patient outcomes.