Urinary Tract Problems May Be Common With IOPD, Despite ERT

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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Lower urinary tract symptoms, including a loss of bladder control and unusual urine flow, are prevalent among children with classic infantile-onset Pompe disease (IOPD) who begin treatment early with enzyme-replacement therapy (ERT), according to a small study.

Findings suggest that “pediatricians should actively seek to recognize children with IOPD and LUTS [lower urinary tract symptoms] and refer these patients to a urologist for evaluation to ensure that early and appropriate treatment is provided,” its researchers wrote.

The study, “Prevalence of lower urinary tract symptoms in children with early‐treated infantile‐onset Pompe disease: A single‐centre cross‐sectional study,” was published in the journal Neurourology and Urodynamics

Pompe disease is a rare genetic condition in which a complex sugar called glycogen builds inside cells, consequently affecting multiple organ systems. Infantile-onset Pompe is typically its most severe form, with symptoms including poor muscle tone, cardiorespiratory distress, and feeding problems that emerge in the first few months of life.

The early initiation of ERT, such as Sanofi Genzyme’s Myozyme (alglucosidase alfa, marketed as Lumizyme in the U.S.), has enabled better survival in these children. As they age, however, new symptoms, including urinary tract and bladder problems, have become apparent.

A research team at Taipei Veterans General Hospital in Taiwan evaluated lower urinary tract symptoms in 14 children with classic infantile-onset Pompe treated at their clinic between August 2019 and March 2021. Newborn screening for Pompe began at that hospital in 2008.

These nine girls and five boys, with a median age of 6, all began treatment with intravenous Myozyme, at median age of 13.5 days old (range, 7 to 83 days). They had been treated for a median of 80.5 months (over 6.5 years).

To the best of our knowledge, only one study has focused on the relationship between lower urinary tract symptoms (LUTS) and incontinence in children” with Pompe, the researchers wrote.

Urinary tract symptoms and their severity were assessed using the Dysfunctional Voiding Scoring System (DVSS), a questionnaire addressing issues with urination and bowel movements (defecation).

Most of the children, 13 of 14, reported at least one relevant symptom. Those commonly observed included the loss of bladder control in nine children (64.3%), and a low frequency of bowel movements in seven children (50%).

Six children (42.9%) — two boys and four girls — showed signs of voiding dysfunction, an inability of the muscles controlling the flow of urine to relax completely, meaning the bladder never empties completely. The median age at ERT initiation between children with and without voiding dysfunction did not differ significantly, the researchers noted.

Each child underwent uroflowmetry to measure the flow of urine after drinking water one hour earlier. The amount of urine remaining in the bladder after urination was also assessed via ultrasound.

Urinary flow patterns were considered abnormal in 10 (71.4%) children, with the flow rate lower than the minimally acceptable value in three of them. Of these 1o children, two also had a greater than normal amount of urine still in the bladder after urinating.

“In the present study, approximately half of our patients with IOPD had voiding dysfunction,” while overactive bladder symptoms like urinary incontinence and urgency were also common, the researchers wrote, highlighting the prevalence of urinary tract symptoms in IOPD patients.

These symptoms are likely related to glycogen buildup in the muscles of the bladder and pelvis, as well as the nerves that supply signals to the urinary tract, the researchers noted.

Notably, these symptoms were present in children diagnosed and started on Myozyme very early in life, suggesting that the therapy may have lower distribution or lesser efficacy in these muscles, they added.

As LUTS is associated with potentially serious issues such as urinary tract infections, kidney problems, and psychological changes, “the early diagnosis and management of lower urinary tract dysfunction in children with IOPD are critical to prevent long‐term complications,” the researchers wrote.

Study limitations included its small patient size that made statistical analyses difficult, they added, noting this is often “inevitable in the study of rare diseases.”