What does it mean to have proteinuria during menstruation?

Proteinuria During Menstruation: Clinical Significance and Evaluation

Proteinuria detected during menstruation should be considered a benign cause and excluded when evaluating for pathological conditions, as menstruation is recognized as a normal physiological cause of transient proteinuria that does not require further evaluation. 1

Understanding Proteinuria During Menstruation

• Menstruation is specifically listed as a benign cause of proteinuria that should be excluded when evaluating patients for asymptomatic microscopic hematuria or proteinuria 1
• Proteinuria during menstruation is typically transient and resolves after the menstrual period ends 1
• This transient proteinuria is not associated with underlying renal disease when it occurs only during menstruation 1

Evaluation Algorithm for Proteinuria

Initial Assessment:

• If proteinuria is detected during menstruation, repeat testing should be performed after the menstrual period has ended 1
• Dipstick testing provides a reasonable assessment of proteinuria, particularly when values are >1 g/L (2+) 1
• For accurate quantification, a spot urine protein/creatinine ratio is preferred over 24-hour urine collection due to convenience and reliability 1

When to Consider Pathological Causes:

• Persistent proteinuria that continues after menstruation ends requires further evaluation 1
• Significant proteinuria is defined as:
  • Total protein excretion >1,000 mg/24 hours (1 g/day) 1
  • Or >500 mg/24 hours (0.5 g/day) if protein excretion is persistent or increasing 1
• Protein/creatinine ratio ≥30 mg/mmol (0.3 mg/mg) is considered abnormal outside of menstruation 1

Clinical Implications

• Normal 24-hour urinary protein excretion varies by sex: 91.2 ± 25.1 mg in men and 62.5 ± 23.6 mg in women 2
• Posture and time of day affect protein excretion - proteinuria is more sensitive to different postures while albuminuria is more affected by different times of urine collection 3
• Protein excretion is significantly higher from 16:00 to 04:00 compared to 04:01 to 16:00 4

Important Considerations

• If proteinuria is diagnosed but subsequent dipstick tests become negative, further quantification tests are appropriate to confirm resolution 1
• In non-pregnant individuals, a urinary protein/creatinine ratio <100 mg/g in untimed urine samples (obtained without exercise, fever, or other evidence of urinary tract disease) is considered normal 5
• The presence of significant proteinuria along with microscopic hematuria should prompt evaluation for renal parenchymal disease or referral to a nephrologist 1

Pitfalls to Avoid

• Do not diagnose pathological proteinuria based on a single test during menstruation 1
• Dipstick testing is not perfect - a small number of proteinuric cases may be missed by a negative dipstick test 1
• Do not rely solely on dipstick testing for definitive diagnosis; confirmation with quantitative methods is recommended when proteinuria persists 1
• Avoid unnecessary workups for transient proteinuria that occurs only during menstruation and resolves afterward 1