Hemostatic System During Childhood

Resident’s Name:  Joanne Lewis                                                                        Date: July 31, 2009

Article title:  Maturation of the Hemostatic System During Childhood

Author(s):  Maureen Andrew, et al

Journal:  Blood

Volume (number):  80(8)

Month, Year:  October 1992

Major topic:  Hemostatic system in childhood

Type of Article:  Prospective cohort study

Main Purpose:  To determine the normal plasma concentrations for the majority of known coagulation proteins during childhood and gain insight into the lower risk of thromboembolic complications in children.

Overview of method of research:  246 healthy children aged 1 to 16 (a minimum of four subjects at each age) who were having minor day surgery were selected to participate in the study.  These children had no history of bleeding problems in the family.  29 healthy adults were also studied.  A 3 mL blood sample was collected from the subjects during routine preoperative blood work.  33 components of the hemostatic system as well as bleeding times were measured.

Findings:  Bleeding times were significantly prolonged during childhood; the upper limit of normal was as high as 13 minutes up to age 10, compared to an upper limit of 7 minutes in adults.  Mean plasma concentrations of the vitamin K-dependent coagulation factors (II, VII, IX, X) were significantly lower in children than in adults.  Mean plasma concentrations of 2 contact factors, XII and XI, were comparable with those of adults until ages 11 to 16, when they decreased slightly.  Plasma concentrations of many coagulation inhibitors showed striking differences from adults.

Key points/Summary:  Plasma concentrations of certain procoagulants were significantly lower at some time during childhood, while others were similar to adults.  Plasma concentrations of 2 inhibitors were increased in early childhood.  The bleeding time was significantly longer for children until approximately 10 years of age compared with adults.  The coagulation system in children is distinctly different from that of adults, and this difference is physiologic.  There is no evidence that children are at greater risk for hemorrhagic problems than adults, and the risk for thrombotic complications is considerably less that for adults.

Assessment of article:  Made some good points about the fallacy of using adult norms to interpret lab values for children…..difficult to get through all the numbers.