Blue Diaper Syndrome (Hartnup Disease)
Blue Diaper Syndrome (Hartnup Disease)
Overview
Blue Diaper Syndrome (BDS) is a rare autosomal recessive metabolic disorder characterized by abnormal tryptophan metabolism and calcium malabsorption. The condition manifests in early infancy and is named for the characteristic bluish discoloration of urine-soaked diapers.
Pathophysiology
- Caused by mutations in the SLC6A19 gene
- Defective tryptophan transport in kidney and intestinal epithelia
- Increased indole production by gut bacteria
- Formation of indicanuria leading to blue-stained diapers
- Associated hypercalcemia and nephrocalcinosis
Clinical Manifestations
Key Symptoms
- Blue-stained diapers (pathognomonic)
- Hypotonia and muscle weakness
- Growth retardation
- Photosensitive skin rash
- Intermittent ataxia
- Neurological symptoms
Associated Features
- Failure to thrive
- Diarrhea
- Irritability
- Seizures (in some cases)
- Mental status changes
Diagnostic Approach
Laboratory Findings
- Elevated urinary indican levels
- Increased urinary calcium excretion
- Abnormal tryptophan loading test
- Elevated serum calcium levels
Imaging Studies
- Renal ultrasonography for nephrocalcinosis
- Bone age studies
- Brain MRI if neurological symptoms present
Genetic Testing
- SLC6A19 gene mutation analysis
- Family genetic counseling
Treatment Strategies
Medical Management
- Dietary tryptophan supplementation
- Nicotinamide supplementation
- Calcium and vitamin D monitoring
- Prevention of nephrocalcinosis
Supportive Care
- Growth monitoring
- Developmental assessment
- Physical therapy if needed
- Nutritional support
Prevention
- Sun protection for photosensitive rash
- Regular monitoring of calcium levels
- Prevention of dehydration
Prognosis and Follow-up
Long-term Outcomes
- Variable prognosis depending on early intervention
- Risk of permanent neurological damage if untreated
- Potential for normal development with appropriate management
- Need for lifelong monitoring
Monitoring Schedule
- Regular calcium level checks
- Growth and development monitoring
- Renal function assessment
- Neurological evaluation
