The Tzu Chi nomograms for maximum urinary flow rate (Qmax ) in children: comparison with Miskolc nomogram

Area of Science:

• Pediatric Urology
• Urodynamics
• Medical Diagnostics

Background:

• Establishing normative data for maximum urinary flow rate (Qmax) in children is crucial for diagnosing lower urinary tract dysfunction.
• Existing nomograms may not adequately account for age, gender, and voided volume variations.

Purpose of the Study:

• To develop the first ranking method-based age- and gender-specific nomograms for Qmax in children.
• To establish minimally acceptable Qmax values for pediatric uroflowmetry interpretation.

Main Methods:

• Two sets of uroflowmetry tests were performed on 1128 healthy children aged 4-12 years.
• Single- and dual-Qmax nomograms were constructed using the higher of two consecutive Qmax values with a voided volume (VV) ≥50 mL.
• Children with suspected urinary tract infections or lower urinary tract dysfunctions were excluded.

Main Results:

• Multivariate analysis confirmed Qmax is significantly influenced by age, VV, and gender (P < 0.01).
• The dual-Qmax nomogram yielded higher percentile values compared to the single-nomogram.
• Minimally acceptable Qmax values at the 10th percentile of the dual-Qmax nomogram were >11.5 mL/s (≤6 years) and >15.0 mL/s (≥7 years).

Conclusions:

• The study recommends repeating uroflowmetry if Qmax falls below the established minimally acceptable age- and gender-specific values.
• The developed dual-Qmax nomograms offer improved diagnostic criteria for pediatric uroflowmetry.
• External validation of these novel dual-Qmax nomograms is warranted.