Comparing Cystatin C– and Creatinine–Estimated Glomerular Filtration Rates in Patients With Thoracic Versus Sacral Motor Levels of Spina Bifida

Abstract

Objective: Patients with myelomeningocele-type spina bifida are at increased risk of developing kidney disease from neurogenic bladder. Differences between creatinine-and cystatin C-estimated glomerular filtration rates were examined in patients with thoracic versus sacral level myelomeningocele given presumed differences in muscle mass. Design: A retrospective chart review (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018) was performed on 57 adults with myelomeningocele [thoracic n = 44 (77%); sacral n = 13 (23%)]. Concurrently obtained creatinine and cystatin C levels were extracted and calculated creatinine-and cystatin C-estimated glomerular filtration rates were compared. Results: Mean creatinine-estimated glomerular filtration rate was significantly higher for thoracic [140.8 ml/min (SD = 23.9)] versus sacral myelomeningocele [112.0 ml/min (SD = 22.6), P = 0.0003]. There was no difference in cystatin C-estimated glomerular filtration rate between sacral [116.6 ml/min (SD = 23.7)] and thoracic myelomeningocele [124.8 ml/min (SD = 17.9)]. The mean difference between creatinineand cystatin C-estimated glomerular filtration rates in thoracic myelomeningocele [24.2 ml/min (SD = 16.3)] was significantly greater than in sacral myelomeningocele [−12.8 (SD = 15.7), P < 0.0001]. Conclusions: There was a significantly higher discrepancy between creatinine-and cystatin C-estimated glomerular filtration rates in thoracic versus sacral motor levels of myelomeningocele. These data suggest that creatinine-estimated glomerular filtration rate may overestimate kidney function in patients with thoracic myelomeningocele. Providers who manage patients with thoracic myelomeningocele should consider monitoring cystatin C to evaluate for underlying renal disease.

Estimating Glomerular Filtration Rate in Pediatric Patients with Neurogenic Bladder: a comparison between Creatinine- and Cystatine C-equations

“…The eGFR calculated through the CKiD-Cr (Schwartz bedside) formula is the common method used to assess kidney function in children. However, the reduced muscle mass in patients with NB turns creatinine into a less accurate marker, as reported in previous studies [5,15,16,23,26,27] .…”

“…In the pediatric population, the most common cause of NB is spinal dysraphism such as various grades of myelomeningocele, lipomeningocele, meningocele and occult lesions. Other etiologies for NB include sacral agenesis, cerebral palsy, traumatic spinal cord injuries, tumors of the brain or spinal cord, muscular dystrophy and other neuromuscular diseases [2,[4][5][6][7][8][9] . Most patients with NB have abnormal body morphology with lower muscle mass, especially in the lower limbs, frequently associated with underdeveloped musculature, orthopedic abnormalities, and gait change [2,[4][5][6]8] .…”

“…Kidney disease is mainly secondary to abnormal bladder function (poor compliance, outlet resistance and elevated intravesical pressure) which leads to a higher pressure in the lower urinary tract with a high risk of developing frequent urinary tract infections, vesicoureteral re ux and renal scaring and damage. Some patients may progress to kidney failure requiring dialysis or kidney transplantation [1,5,[12][13][14] .…”

“…On the other hand, cystatin C (CysC) is a low molecular-weight protein, produced by all human nucleated cells, almost completely ltered by the glomeruli and unaltered by body size and composition, muscle mass, gender and age [1,5,16,19] . However, CysC determination is less available and more expensive and so renal function assessment based on CysC is not usually recommended, except for speci c clinical situations [20,22] .…”

“…Previous studies report an important variability between eGFR calculated by Cr and CysC-based formulas in patients with spina bi da or NB, both in adults and children. Furthermore, in those studies, the eGFR based on CysC upgraded CKD to a more advanced stage [1,5,15,16,21,23,24] . However, comparative studies of eGFR between patients with NB and different levels of neurological damage, and consequently with different degrees of muscle mass reduction, are scarce.…”