From “Doctor Mukesh“: a 3 month-old with an old intracranial bleed and an sol has a markedly prolonged prothrombin time (PT) and partial thromboplastin time (PTT) and is bleeding from IV sites but looks pretty alright. What are the possibilities?
Hello, and thank you for your question. The PT and PTT reference intervals at three months vary slightly from adult ranges, at 10–14.2 and 29.0–50.1 seconds, respectively,per Andrew M, et al. Development of the hemostatic system in the neonate and young infant. Am J Pediatr Hematol Oncol 1990;12:95-104. Prolongation of both could imply vitamin K deficiency, immature or diseased liver, or a congenital deficiency of factors II (prothrombin), V, or X, or fibrinogen deficiency. For a 3-MO, the factor V reference interval (RI) is 48–132% and the factor X RI is 35–107% If factors V and X are both decreased, suspect immature or diseased liver, confirm with a liver enzyme panel. If only factor X is decreased, check also factor II (prothrombin, RI 45–105%). If both are decreased, it is likely vitamin K deficiency, which may be treated with oral or IV vitamin K. A congenital single-factor deficiency of factors II, V, or X is also possible, and will be detected by factor assay. Include a fibrinogen assay, RI 150–379 mg/dL. Finally, although the PT and PTT results indicate a coagulopathy, be sure to also perform a platelet count, RI 150–450,000/μL. Please feel free to follow up when you obtain additional information.