What is the initial lab test to order for a 7-year-old girl presenting with urinary incontinence?

Initial Laboratory Testing for Urinary Incontinence in a 7-Year-Old Girl

The initial laboratory test to order for a 7-year-old girl presenting with urinary incontinence is a urine dipstick test. 1

Diagnostic Approach

Initial Assessment

• A urine dipstick test is the sole obligatory laboratory test for children with urinary incontinence, particularly to rule out underlying medical conditions 1
• The dipstick should test for:
  • Leukocyte esterase (to detect pyuria/inflammation) 2
  • Nitrites (to detect bacterial infection) 2
  • Glucose (to rule out diabetes mellitus) 1
  • Protein (to rule out kidney disease) 1

Interpretation of Results

• Glycosuria requires immediate exclusion of diabetes mellitus 1
• Proteinuria in repeat samples should prompt investigations for kidney disease 1
• Positive leukocyte esterase and/or nitrites suggest urinary tract infection (UTI) and should be followed by urine culture 2, 3
• The sensitivity of leukocyte esterase for UTI is approximately 82% with specificity of 92% 3

Additional Diagnostic Tools

Frequency-Volume Chart/Bladder Diary

• After the initial urine dipstick, completion of a frequency-volume chart or bladder diary is recommended to: 1
  • Provide objective data supporting the history
  • Help detect children with non-monosymptomatic enuresis
  • Provide prognostic information
  • Identify children requiring additional evaluation
  • Detect children with polydipsia
  • Assess family adherence to medical instructions

When to Consider Additional Testing

• If the dipstick reveals abnormalities (positive for leukocyte esterase, nitrites, glucose, or protein), further testing is warranted 1
• If the child has a history of UTI or non-monosymptomatic enuresis, additional evaluation may be needed 1
• For children with atypical or recurrent UTI symptoms, ultrasound of the kidneys and bladder may be appropriate 1

Important Considerations

When Not to Order Additional Tests

• Routine blood tests are not indicated for urinary incontinence evaluation 1
• Routine ultrasound of the kidneys and upper urinary tract is not warranted in simple cases of urinary incontinence 1
• Invasive tests like voiding cystourethrography should be reserved for cases with suspected anatomical abnormalities or recurrent UTIs 1

Special Considerations

• Physical examination should focus on identifying signs of constipation, which can contribute to urinary incontinence 1
• Examination of the back and external genitals is mandatory in children with a history of UTI 1
• For children with daytime wetting, abnormal voiding patterns, history of UTIs, or genital abnormalities, urologic referral may be warranted 1

Common Pitfalls to Avoid

• Don't assume all urinary incontinence in children is behavioral or developmental without ruling out medical causes 1
• Don't miss constipation as a contributing factor to urinary incontinence 1
• Avoid unnecessary invasive testing in uncomplicated cases 1
• Don't rely solely on dipstick testing without clinical correlation - sensitivity is good but not perfect 3
• Remember that a positive leukocyte esterase test alone has moderate sensitivity (83%) but limited specificity (78%) for UTI, making it insufficient as a standalone diagnostic test 2