Prothrombin in Newborns and During the First Year of Life

Abstract

The hypoprothrombinemia of the newborn was first demonstrated by Brinkhous et al. in 1937, by use of their two-stage prothrombin assay (5). Waddell and coworkers (41) were the first to associate the hypoprothrombinemia, expressed by a prolonged "prothrombin time" (34), with vitamin K deficiency. Several investigators (7,29,30,35) repor,ted that prothrombin decreased during the first few days of life and then increased to normal values within a week (35) or within a year (5, 6, 30), depending on the method used for the assays. It has been postulated that the postnatal decrease of prothrombin and related coagulation factors might be explained by a quick reduction of the transferred maternal factors combined with a slow synthesis of coagulation factors in the infant liver (16). Because of the potential bleeding risk in this age period vitamin K prophylaxis was introduced and a safe dosage established (1, 6, 10, 36).Studies of prothrombin and other coagulation factors in the newborn have resulted in some paradoxical findings. Thus the one stage "prothrombin time" according to Quick (34) gives normal values in newborns in spite of definitely subnormal activities of factors VII, X and prothrombin (factor II), assayed by specific methods. In adults the Quick test registers deficiencies of these factors. Several explanations have been offered: molecular dif-18 -712877 A c t 3 Padiat Scand 60 ferences between infant and adult prothrombin (30, 36) and fibrinogen (20, 42) or possibly an excess of factor V (11) in the newborn. It is evident that testing techniques used must always be taken into account when comparing coagulation assay results especially in this age In most Swedish hospitals "prothrombin index" according to 34) and the prothrombin-proconvertin assay according to Owren & Aas (31) have been replaced by thrombotest according to Owren (32) as the latter test is performed with a readymade, freeze-dried reagent and is well standardized. The Quick-Lehmann test registers deficiencies of factors 11, V, VII, X as well as fibrinogen (factor I), but with varying sensitivity. The prothrombin-proconvertin and the thrombotest reagents contain bovine fibrinogen and factor V, and the methods register deficiencies of vitamin K dependent coagulation factors, i.e. factors 11, VII and X, and the thrombotest to a certain extent also factor IX.The present investigation was undertaken to study a new specific two-stage assay of prothrombin (3, 28) in newborns. Further, the correlation between thrombdest activity and prothrombin concentration was studied, as well as prothrombin and proconvertin during the first year of life. The study was especially concerned with cases of decreased prothrombin Acta Pcediat Scand 60 group (1). 270 I. Nor& et al. 2.8, 2.6. 2.4-22-5 20.

Short communication

“…Since TOWNSEND [10] described the haemorrhagic disease of the newborn, many studies on this syndrome have appeared, which have shown that the pathogenesis is multiple. One of the main causes has been shown to be low vitamin K-dependent' clotting factors in the newborn period and several reports deal with the effect of vitamin K prophylaxis [3,6,9,11]. The majority of cases of haemorrhagic disease of the newborn occur on the second and third day.…”

Specific Determinations of Prothrombin for Evaluation of Liver Function

“…Prothrombin in normal individuals of different age was also investigated and the influence of antithrombin on the prothrombin determinations was evaluated. Results from investigations of prothrombin during infancy and in subjects on oral anticoagulant treatment have been reported elsewhere (17,18).…”

Preprothrombin and Prothrombin in Full-Term Newborns

“…The hemostatic mechanism of the newborn [3,4,14,15,17,21,27,28] is characterized by hypoprothrombinemia related to vitamin K deficiency. The postnatal diminution of prothrombin is explained by a rapid reduction of the factor present at birth combined with a slow synthesis of the vitamin K-sensitive coagulation factors in the newborn liver [5].…”