Evaluation of the Response of Sickle Cell Disease in Steady State to Anaemia

BACKGROUND: Sickle cell disease (SCD) is a genetic disease characterized by episodes of crises interrupted by periods of relatively stable clinical state known as steady state. The erythroid response seen in steady state may be inadequate in some patients. Factors responsible for inadequate erythroid response has not been adequately investigated in our environment. OBJECTIVE: To evaluate the response of sickle cell disease in steady state, to anaemia,among SCD patients in Calabar. METHODS : This is a cross sectional study to be conducted at the University of Calabar Teaching Hospital (UCTH), Calabar, Cross River State. Sixty SCA subjects in steady state and 30 controls participated in the study. Blood samples were collected for estimation of haematocrit, reticulocyte count, serum transferrin receptor (sTfR), erythropoietin and C-reactive protein (CRP). Haematocrit was estimated with haematology autoanalyzer; reticulocyte count was estimated by supravital staining using brilliant cresyl blue and counting of reticulocyte on microscopic examination of stained slides; sTfR,CRP and EPO were estimated using an enzyme linked immunosorbent assay methods.The data was analyzed using the IBM version of the statistical package for social sciences (SPSS) version 21. The difference in mean EPO,CRP and sTfR levels were tested using students t test. P value was set at ≤0.05. RESULTS: The mean age of the SCA subjects did not differ significantly from those of the controls (27.7 ± 8.9 vs. 29.3 ± 9.1 years; p = 0.442). The SCA subjects comprised of 31 (51.7%) males and 29 (48.3%) of females and the controls 13 (43.3%) males and 17 (56.7%) of females. The differences in sex distribution between the SCA and control population was not statistically significant (p = 0.510).The mean haematocrit of the SCA subjects was significantly reduced compared to the controls (23.8 ± 5.2% vs. 39.0 ± 5.5%; p = 0.001). The mean reticulocyte count of SCA subjects was significantly higher than the controls (3.3 ± 1.0% vs. 1.1± 0.4%; p <0.001). Similarly the mean corrected reticulocyte count and reticulocyte production indices were also significantly higher in the SCA subjects compared to the controls (2.2 ± 0.8 vs. 1.1 ± 0.4%; p = 0.000) and (1.3 ± 0.6 vs. 1.0 ± 0.4%; p = 0.028) respectively. Twenty eight (46.7%) SCA subjects had inadequate response.The mean erythropoietin levels in the SCA subjects did not differ significantly from the controls (234.4 ± 92.2IU/mL vs. 239.6 ± 115.1IU/mL; p = 0.509). Serum transferrin receptor level was significantly elevated in SCA subjects compared to the controls (97.3 ± 19.2 vs. 54.4 ± 16.6; p < 0.001). There was no significant difference in mean EPO between SCA subjects with low reticulocyte production index (RPI) and those with adequate RPI (243.4 ± 98.4 vs. 226.8 ± 87.4IU/mL, p = 0.496). The mean sTfR was significantly increased in SCA subjects with low RPI compared to those with adequate RPI (102.8 ± 18.7 vs. 92.5 ± 18.5, p = 0.036). There was no significant difference in mean CRP between those SCA with low and those with adequate RPI (4.1 ± 2.0 vs. 4.0 ± 2.1, p = 0.736). CONCLUSION: A good proportion of SCA subjects in steady state have inadequate erythroid response to anaemia. Iron deficiency and blunted erythropoietin response contributes to inadequate erythroid response in SCA subjects in steady state.