Serum Thrombospondin-1 as a Biomarker of Vaso-occlusive Crises in Adults with Sickle Cell Anaemia: Associations with Platelet Indices and Inflammation

Background: Thrombospondin-1 (TSP-1), a platelet-derived adhesive glycoprotein, contributes to vaso- occlusive crises (VOC) in sickle cell anaemia (SCA). Although elevated TSP-1 levels have been reported in paediatric and high-income settings, its relationship with platelet indices in African adults with SCA remains poorly defined. This study aimed to evaluate serum TSP-1 concentrations in adult Nigerian patients with SCA during VOC and steady state, and to explore associations with platelet indices and haematological parameters. Materials and Methods: We conducted a cross-sectional comparative study at Ahmadu Bello University Teaching Hospital (ABUTH), Zaria, Nigeria. Participants comprised 40 SCA patients in VOC, 40 in steady state, and 40 age- and sex-matched HbAA controls. Clinical data were obtained using a structured questionnaire. Complete blood counts and platelet indices were analysed using an automated haematology analyser, and serum TSP-1 was quantified by enzyme-linked immunosorbent assay (ELISA). Group comparisons were performed using ANOVA, correlations were assessed with Pearson's or Spearman's tests as appropriate, and predictors of TSP-1 were identified by multivariable linear regression. Results: A total of 120 participants were enrolled (median age 26 years, 67·5% female). Mean TSP-1 levels were significantly higher in VOC (406·0 ng/mL, SD 164·6) than steady state (312·4 ng/mL, SD 145·6) and controls (192·3 ng/mL, SD 121·2; p < 0·001). In steady state, TSP-1 correlated positively with haemoglobin (r = 0·42, p = 0·01) and haematocrit (r = 0·49, p = 0·01), but inversely with mean platelet volume (r = –0·38, p= 0·02) and platelet large cell ratio (r = –0·36, p = 0·02). During VOC, TSP-1 showed a modest inverse correlation with numeric pain scores (rs = –0·41, p = 0·01). In multivariable regression, white blood cell count independently predicted TSP-1 levels (β = 7.309, t = 2.285, p = 0.024). Conclusion: TSP-1 levels were markedly elevated during VOC in adult Nigerian patients with SCA and were independently associated with leukocytosis. Platelet indices are significantly altered but added limited predictive value for TSP-1 variance, supporting their role as complementary rather than substitute biomarkers.