Evaluation of primary hemostasis in neonates with a new in vitro platelet function analyzer.

With the use of the PFA-100 platelet function analyzer to evaluate primary hemostasis in whole blood, measured as closure time (CT), neonates had shorter CTs than members of an adult control group. Multivariate analysis of measures that contribute to primary hemostasis showed that higher hematocrits and increased ristocetin cofactor activity were the best correlates for CTs of cord blood. These 2 factors may also enhance primary hemostasis in vivo and compensate for the impaired platelet function of the newborn.

Acquired inhibitors to factors V and X after exposure to topical thrombin: interference with monitoring of low molecular weight heparin and warfarin.

Repeated surgical exposure to topical bovine thrombin is known to be associated with the development of antibodies to bovine and human thrombin and factor V. This is demonstrated by abnormalities of in vitro coagulation assays and, rarely, postoperative bleeding. We describe a 4-year-old child in whom an antibody to bovine factor X developed after cardiac surgery; this antibody interfered with the heparin anti-Xa assay, thereby complicating the monitoring of heparin therapy.

A multicenter study of the treatment of childhood chronic idiopathic thrombocytopenic purpura with anti-D.

We evaluated the effects of the intravenous administration of anti-D, an immune globulin directed at the D antigen on erythrocytes that is purified from plasma from sensitized persons, on patients with idiopathic thrombocytopenic purpura. To determine the most effective dose, the duration of response, and the side effects of this therapy in children, we performed a multicenter cohort study of escalating doses of intravenously administered anti-D in children aged 1 to 18 years with chronic idiopathic thrombocytopenic purpura, defined as idiopathic thrombocytopenic purpura persisting for more than 6 months with a platelet count of less than 50 x 10(9) cells/L. Twenty-five Rh-positive children received increasing doses of anti-D as follows: day 1, 25 micrograms/kg; day 2, 25 micrograms/kg; day 7, 35 micrograms/kg; day 14, 45 micrograms/kg; and day 21, 55 micrograms/kg. Administration of anti-D was stopped after day 21 or when the platelet count rose to greater than 150 x 10(9) cells/L or the hemoglobin level was 100 gm/L. Platelet count was less than 50 x 10(9) cells/L in all children before treatment. A response was defined as an increase in the platelet count to more than 50 x 10(9)/L and a doubling of the pretreatment platelet count. Of 25 children, 23 (92%) had responses by day 7 of the initial treatment protocol. Eighteen children (72%) had platelet counts greater than 150 x 10(9) cells/L by day 7 after two doses of anti-D. Median duration of response was 5 weeks (range 1 to 24 weeks). Average drop in hemoglobin level was 13.7 gm/L; in one child (a nonresponder) hemoglobin value fell to less than 100 gm/L. No other untoward side effects were seen. Of the 23 children who responded, 21 were retreated with one dose of anti-D when platelet counts returned to baseline values of less than 50 x 10(9) cells/L; all but three of the children who underwent retreatment showed a response the second time. Sixteen children continued to receive intermittent anti-D therapy after completion of the study, and all continued to have excellent responses. We conclude that anti-D is a safe, effective, and relatively inexpensive therapy for childhood chronic idiopathic thrombocytopenic purpura.

Analbuminemia in a neonate.

A small-for-gestational-age infant, found to have analbuminemia in the neonatal period, is reported and the twelve cases recorded in the world literature are reviewed. Patients lacking this serum protein are essentially asymptomatic, apart from minimal ankle edema and ease of fatigue. Apparent compensatory mechanisms which come into play when serum albumin is low include prolonged half-life of albumin and transferrin, an increase in serum globulins, beta lipoprotein, and glycoproteins, arterial hypotension with reduced capillary hydrostatic pressure, and the ability to respond with rapid sodium and chloride diuresis in response to small volume changes. Examination of plasma amino acids, an investigation not previously reported, revealed an extremely low plasma tryptophan level, a finding which may be important in view of the role of tryptophan in albumin synthesis.