A patient with anemia is found to have a low reticulocyte count and a high level of lactate dehydrogenase (LDH) in their serum. What is the most likely diagnosis?

A Autoimmune hemolytic anemia
B Hereditary spherocytosis
C Paroxysmal nocturnal hemoglobinuria (PNH) ✓
D Hemolytic uremic syndrome (HUS)

Explanation

A low reticulocyte count indicates inadequate bone marrow response, while a high level of LDH suggests intravascular hemolysis. PNH is characterized by intravascular hemolysis, which would lead to an increase in LDH levels.

Source

New England Journal of Medicine
Hematology Hematology: Anemia Hematology: Anemia Medium MEDICAL Confidence: high