Associations between Sickle Cell Disease, Pica and Enuresis

Introduction: Sickle cell disease (SCD) is a genetic disorder that impacts the shape and functional capacity of red blood cells. Beyond altered cerebral perfusion, individuals with SCD have higher rates of neurodevelopmental disorders (NDDs), including attention deficit hyperactivity disorder (ADHD), intellectual disability, and specific learning disabilities. Past research has shown that in adolescent populations with either SCD or NDDs, pica, the act of eating non-food items, and enuresis, or involuntary urination, commonly occur. Both pica and enuresis are associated with biopsychosocial issues in typically developing children. However, the etiology of both of these disorders, as well as the confluence of NDDs and SCD on their occurrence, remains unclear.

Hypothesis: The objective of this study was to determine the rates of pica and enuresis in a local pediatric SCD clinic and determine if these conditions present differently and/or have different associations in SCD than in the general population. We hypothesized that NDDs would serve as risk factors for both pica and enuresis with both conditions being associated with increased sickle cell severity.

Methods: To test these hypotheses, we performed a retrospective chart review on 275 SCD patients. Using Epic, patients who at point visited either Kennedy Krieger Institute or John Hopkins Medical Center for SCD and were in an existing database were queried. Patients in the database ranged from 1 to 17 years old and were predominantly Black, non-Hispanic individuals. Primary keywords searched included: “enuresis, pica, bedwetting, diurnal, nocturnal, eating, non-food, peeing, urination, incontinence.”

Results: Pica was reported in 9% (Table 1), while enuresis was reported in 27% of patient charts reviewed (Table 2). Both enuresis (Chi-squared test, p = 0.0050) and pica (Chi-squared test, p = 0.0190) were significantly linked to NDD occurrence, with pica being nearly three times as likely to occur alongside NDDs and/or enuresis. Notably, SCD patients with pica most commonly ate paper or wood, different from the general population with pica primarily eating rocks or dirt. Through the Wilcoxon rank sum test, we also noted no associations between pica and median hemoglobin (p=0.9572), ferritin (p=0.6209), iron serum (p=0.9500), total iron-binding capacity (p=0.1598), iron saturation (p=0.6292), or transferrin (p=0.1765) levels. Beyond this, our data also validate prior results demonstrating that enuresis is associated with both SCD type and hydroxyurea usage. There were no significant differences in rates of enuresis between males and females, unlike what is seen in the general population. Sleep apnea was associated with enuresis, at a higher rate than in the general population (Chi-squared post-hoc residual test, p = 0.0004). Patients with SCD and enuresis had higher mean reticulocyte counts and lower mean hemoglobin levels than patients with SCD without enuresis, consistent with increased hemolysis and worsening SCD severity.

Conclusion: These results suggest etiologies for pica and enuresis in SCD patients may differ from the general population. As pica and enuresis commonly occur together with NDDs, there is a clear need for increased standardized screening for these conditions in clinics. Understanding why the risk factors for these conditions in SCD differ from the general population requires further investigation into their respective mechanisms of disease.