Full Blood Count Platelet Parameters in Sickle Cell Disease: A Systematic Review of Thrombocytosis, Thrombocytopenia, and Clinical Implications
Jacques Forwah Ndeh *
Department of Hematology and Blood Transfusion Sciences, Faculty of Clinical Sciences, University of Calabar Teaching Hospital, Calabar, Cross River State, Nigeria.
Edung Emen Samuel
Emergency Department, Basildon and Thurock University Hospital, London, NHS Trust Foundation, United Kingdom.
Ofonime Benjamin Essien
Department of Hematology and Blood Transfusion Sciences, Faculty of Clinical Sciences, University of Calabar Teaching Hospital, Calabar, Cross River State, Nigeria.
Bassey Okon Bassey
Department of Hematology and Blood Transfusion Sciences, Faculty of Clinical Sciences, University of Calabar Teaching Hospital, Calabar, Cross River State, Nigeria.
Mansurat Oluwasshola Alabi
Department of Obstetrics and Gynecology, Usmanu Danfodiyo, University, Sokoto, Sokoto State, Nigeria.
Ihuoma Fidelia Onunaku
Department of Obstetrics and Gynecology, Imo State University Teaching Hospital, Orlu, Imo State, Nigeria.
Joy Oyemwen Aikpitanyi
Department of Geriatrics and General Internal Medicine, Barking Havering Redbridge University of Romford, NHS Trust, UK.
Diderot Tiemen Charles
Department of Orthopaedics and Traumatology, University of Calabar Teaching Hospital, Calabar, Cross River State, Nigeria.
Ewa Anthony Obi
Department of Family Medicine, University of Calabar Teaching Hospital Calabar, Cross River State, Nigeria.
Idiege Idiege Omang
Department of Surgery, University of Calabar Teaching Hospital, Calabar, Cross River State, Nigeria.
Edomaruse Maxwell Joseph
Department of General Medicine, Agbani General Hospital Enugu, Enugu State, Nigeria.
Alu Owere Emmanuel
Department of General Medicine and Emergency, Ministry of Health, Baa Atoll, Maldives.
Prince-Nnabugwu Ruth Amarachukwu
Department of Emergency Medicine, National Hospital Abuja, FCT Abuja, Nigeria.
Adegboyega Akintola
Department Acute Medicine, WWL NHS Trust, Wigan, England.
Asuquo Ukemeobong Michael
Department of Radiology, University of Port Harcourt Teaching Hospital, River State, Nigeria.
Maduka Ekene Ekezie
Department of ENT HNS, FTH, Owerri, Imo State, Nigeria,
Gbeminiyi Ebenezer Adekanmbi
Department of Internal Medicine, South Regional Health Authority, Clarendon, Jamaica.
Ike-Ogbonna Ginikachi Valerie
Department of Obstetrics & Gynaecology, Army Command and NAOWA Hospital, Asokoro, Abuja, Nigeria.
Agbayewa Ademola
Department of Emergency Medicine, National Health Service (NHS), Coventry, United Kingdom.
Chioma Kenis Onyejekwe
Department of Emergency Medicine, National Health Service (NHS), Coventry, United Kingdom.
Oluwatobiloba Akinwale
Department of Acute Medicine, East Cheshire NHS Trust, Macclesfield, England.
Egwowa Elo-Oghene Mary
Department of Obstetrics and Gynaecology, Messentia Medicare Maidstone, United Kingdom.
Bushirat Mulero
Department of ENT, East Suffolk and North Essex NHS Foundation Trust, Ipswich, United Kingdom.
Sally Tsagli
Department of Internal Medicine, Ga East Municipal Hospital, Accra, Ghana.
Abdullah Damilare Shonola
Department of Psychiatry, Queen Mary’s Hospital, London, United Kingdom.
Oyibo Basil Eze
University of Roehampton, London, United Kingdom.
Princess Adebanwi
Department of Pediatrics, Sheffield Children NHS Foundation, Shieffield, United Kingdom.
Akaba Kingsley Onoridea
Department of Hematology and Blood Transfusion Sciences, Faculty of Clinical Sciences, University of Calabar, Cross Rivers State, Nigeria.
Nnaji Chimuanya Joseph
Department of Surgery, Nnandi Azikiwe University Teaching Hospital Nnewi, Anambra State, Nigeria.
Ushie Godwin Abua
Department of Hematology and Blood Transfusion Sciences, Faculty of Clinical Sciences, University of Calabar, Cross Rivers State, Nigeria.
Immaculate Ihuoma Ekeagba
WORCACCCE Union Group Integrated Healthcare Sciences, Technological Development and Training and Innovative Research Foundation (WUGIHSTTAIRF), P.O Box 45, Bamenda, North West Region, Cameroon.
Tams Isaac Tamunobelema
Department of Internal Medicine, University of Port Harcourt Teaching Hospital, Rivers State, Nigeria.
Abeshi Sylvester Etenikang
Department of Obstetrics and Gynecology, University of Calabar Teaching Hospital, Calabar, Cross River State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Sickle cell disease (SCD) is characterized by chronic hemolysis, endothelial dysfunction, and systemic inflammation, each of which disrupts platelet homeostasis. The full blood count (FBC), the most universally available hematological test, remains underutilized in routine clinical interpretation of thrombocytosis and thrombocytopenia in SCD. Both abnormalities contribute to the hypercoagulable phenotype and organ complications of SCD; however, their prevalence, causes, and prognostic significance vary by genotype, clinical state, and geography.
Objective: To evaluate the utility of the FBC in detecting, understanding, and managing platelet abnormalities in SCD by synthesizing 2020–2026 evidence on prevalence, etiology, pathophysiology, clinical implications, complications, and management strategies.
Methods: This systematic review followed PRISMA 2020 guidelines. Ten databases were searched from 1 January 2020 to 31 March 2026; searches were executed on 2 April 2026 and updated on 10 April 2026. Of 680 records retrieved, 56 duplicates were removed, yielding 624 unique records; 550 underwent full-text assessment. Sixty-three studies met all inclusion criteria. Prevalence data were pooled using random-effects meta-analysis; publication bias was assessed using Egger’s and Begg’s tests, with trim-and-fill correction applied where asymmetry was detected.
Results: Observed prevalence of thrombocytosis was 30.9% (95% CI: 26.4–35.7%) at steady state and 66.1% (95% CI: 61.3–70.6%) during acute events; trim-and-fill-adjusted steady-state estimates were 28.4% (95% CI: 24.1–33.0%) for thrombocytosis and 19.1% (95% CI: 15.6–23.2%) for complication-associated thrombocytopenia. Substantial between-study heterogeneity was observed across all outcomes (I² range: 68.3–82.4%). Thrombocytopenia occurred in 7.4% (95% CI: 5.9–9.2%) at steady state and 22.0% during complications. Thrombocytosis was predominantly reactive, driven by functional asplenia, haemolysis-induced thrombopoietin release, iron deficiency, and inflammatory cytokines. Thrombocytopenia reflected acute pathology including splenic sequestration, thrombotic microangiopathy, sepsis, and aplastic crisis. A multi-center cohort study of SCD patients in Oman (Alkindi et al., 2024) identified a rapid decline in platelet count as a significant correlate of mortality, alongside leukocytosis and elevated haemolytic markers, with thrombocytopenia preceding multiorgan failure in non-survivors.
Conclusions: The FBC is a high-yield, low-cost diagnostic and prognostic tool in SCD. Integrating platelet count, MPV, and PLR with clinical context and hematological markers may improve risk stratification, though prospective validation of specific thresholds for MPV and PLR in SCD is still required. Management should be etiology-specific, with platelet transfusion reserved for life-threatening hemorrhage. Standardizing FBC interpretation through simple, resource-appropriate algorithms can enhance early complication detection, particularly in low-resource, high-burden settings.
Keywords: Sickle cell disease, full blood count, thrombocytosis, thrombocytopenia, platelet indices, mean platelet volume, platelet-to-lymphocyte ratio, vaso-occlusive crisis, hydroxyurea, systematic review, hematology, platelet homeostasis