Question

Since birth, a 2-year-old female toddler has complained of blackish discoloration on wet nappy drying. She was the sole kid of a nonconsanguineous couple, and she was doing well. Her developmental milestones were all within normal limits. There were no abnormalities discovered during the clinical assessment. The urine sample was tested for silver nitrate and Benedict's test, which both came back positive.

a) What would your first diagnosis be?
b) What tests would you recommend in order to confirm your diagnosis?

Answer 1

The first diagnosis could be a metabolic disorder like Alkaptonuria, suggested by the blackish discoloration of the urine upon drying. To confirm this, tests such as quantitative amino acid analysis, urine organic acid analysis, and potentially a specific enzyme assay are recommended.

Step-by-step explanation:

Initial Diagnosis and Recommended Tests

Based on the information provided, the first diagnosis of the 2-year-old female toddler with blackish discoloration on a wet nappy could be a metabolic disorder such as Alkaptonuria, where homogentisic acid oxidizes upon exposure to air causing the urine to darken. The presence of a positive silver nitrate and Benedict's test indicates the presence of reducing substances in the urine, which may point towards other conditions like an inborn error of metabolism.

To confirm a diagnosis, I would recommend the following tests:

• Quantitative amino acid analysis to check for abnormal levels of specific metabolites.
• Urine organic acid analysis to identify any abnormal excretion patterns associated with metabolic disorders.
• A specific enzyme assay, if a particular metabolic disorder is suspected based on preliminary results.

These tests would provide a more accurate assessment of the toddler's metabolic function and help identify any specific disorders.