Vitamin K deficiency


Vitamin K deficiency


0 / 9 complete

USMLE® Step 1 questions

0 / 3 complete

High Yield Notes

4 pages


Vitamin K deficiency

of complete


USMLE® Step 1 style questions USMLE

of complete

A 6-day-old boy is brought to the emergency department by his parents because of easy bruising. The infant was born at 38 weeks to a 23-year-old primigravida woman via normal vaginal delivery at home. This is his first medical evaluation. The patient’s mother took prenatal vitamins and maintained a healthy diet during pregnancy. Family history is unremarkable. Vitals are within normal limits. Physical examination reveals an alert infant. Examination shows multiple ecchymoses visible on upper and lower extremities. The remainder of the examination is unremarkable. Laboratory results are shown.
 Laboratory features 
 Laboratory value  Result 
 Platelet count    230,000/mm3 
 Bleeding time  5 minutes 
 Prothrombin time   27 seconds 
 Activated partial thromboplastin time  42 seconds 

Which of the following is the most likely cause of this infant’s presentation?


Vitamin K deficiency is a form of avitaminosis resulting from insufficient vitamin K1 or vitamin K2 or both. It can develop as a result of low vitamin K stores, a sterile gut, gestational use of coumarin-like anticoagulants, chronic use of antibiotics, and prolonged diarrhea. Symptoms include bruising, petechiae, hematomas, oozing of blood at surgical or puncture sites, stomach pains, risk of massive uncontrolled bleeding, cartilage calcification, and severe malformation of developing bone or deposition of insoluble calcium salts in the walls of arteries. In infants, it can cause some birth defects such as an underdeveloped face, nose, bones, and fingers. Treatment involves administration of vitamin K, as well as intake of vitamin K-rich foods.


Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.