Risk factors for thromboembolism and pulmonary artery hypertension following splenectomy in children with hereditary spherocytosis

BACKGROUND: The aim was to study risk-factors for vascular thrombosis and incidence of pulmonary artery hypertension (PAH) in splenectomized children with hereditary spherocytosis (HS) at a single center. PROCEDURE: Pre- and post-splenectomy hemoglobin and platelet counts were recorded. Post-splenectomy lipid-profile, fibrinogen, D-dimer, CRP and anti-coagulant-protein levels were compared to established controls. Echo-Doppler was performed for PAH. RESULTS: Twenty-six children with HS had undergone splenectomy; the mean age at surgery was 7.9 ± 3.7 years. Nineteen of the 26 were prospectively investigated at a median duration of 4.5 years (range: 4 months to 19 years) following splenectomy. Thrombocytosis was observed in 19 (73%), whereas no patient had erythrocytosis at the last follow-up visit. Total cholesterol, LDL-C, HDL-C, and triglyceride levels were not deranged (P ≥ 0.3). Mean CRP levels (males: 2.8 ± 0.5; females: 2.1 ± 0.5 mg/L) were significantly higher than described for normal children (P < 0.001). Six (23%) patients had a positive D-dimer assay. Protein S, anti-thrombin-III and fibrinogen were in range. A single patient had a borderline low protein C activity. Lupus anticoagulant and anti-cardiolipin antibody assays were negative. The mean tricuspid regurgitant jet velocity (TRJV) was 1.8 ± 0.55 meter per second (range: 0-2.4). None had a TRJV ≥2.5 meter per second to suggest PAH. CONCLUSIONS: There was no evidence of PAH, dyslipidemia, elevation of fibrinogen or a reduction in anti-coagulant proteins, at a median follow-up duration of 4.5 years following splenectomy in children with HS. However, elevated CRP level (42%), persistent thrombocytosis (73%) and elevated D-dimer levels (23%) were observed. These have been recognized as risk factors for cerebrovascular and coronary heart disease.