On June 28, this comment was appended by “nomorefede” to a 2009 post from Sue Hollister describing a newborn with factor IX deficiency:
I comment you a case in a newborn hospital:
Prothrombin time (PT): 55 sec
Partial thromboplastin time (PTT): 60
Fibrinogen: 130 mg/dL
Factor II: 8%.
The baby has central bleeding. It was aplicted fresh plasma.The factor II level didn’t rise very much. This is the first case of this type. Can you help with some information.Thank you.
Hello, and thank you for your question. I’ve reprised it from our “comments” section to ensure it attracts attention. The foremost possibility is vitamin K deficiency. I would recommend assaying at least one additional vitamin K-dependent factor, perhaps factor VII, the factor with the most rapid turnover. If the infant has since received vitamin K, the results should be normal, of course.
The fibrinogen level is relatively unremarkable, according to Andrew M, et al. Development of the hemostatic system in the neonate and young infant. Am J Pediatr Hematol Oncol 1990;12:95-104, which indicates the lower limit of normal for a newborn (1 day) to be 167 mg/dL. Of course, low fibrinogen could also mean an immature or diseased liver.
When fresh or thawed frozen plasma fails to raise factors to the level predicted, you may consider a factor inhibitor, however antibodies against prothrombin are rare and the possibility they would be transferred from mother to fetus rarer still. In adults, plasma may be expected to raise the deficient factor to no more than 30% activity, as the volume of plasma may induce circulatory overload. I suspect the rise in a newborn may be smaller. I’d be happy to hear from others about this case, especially those experienced with newborn factor deficiencies.