What causes ochronosis in alkaptonuria?

Accumulation of homogentisic acid (HGA) in connective tissue causes dark brown/black discoloration (ochronosis) of cartilage, tendons, ligaments, and heart valves over decades.

How does nitisinone treat alkaptonuria?

Nitisinone inhibits 4-hydroxyphenylpyruvate dioxygenase, the enzyme two steps above HGD in the tyrosine pathway, dramatically reducing HGA production and urinary excretion.

What joints are most commonly affected in alkaptonuria?

Large joints (spine, hips, knees, shoulders) are most affected; ochronotic arthropathy resembles osteoarthritis but occurs earlier (3rd-4th decade) and progresses faster.

What clinical signs suggest alkaptonuria diagnosis?

Darkening urine on standing, blue-gray ear cartilage discoloration, and early-onset spondyloarthropathy are classic triad; homogentisic aciduria confirms the diagnosis.

What monitoring is needed with nitisinone therapy?

Plasma tyrosine levels (must stay <700 μmol/L), annual ophthalmology (corneal deposits possible), and urinary HGA to confirm therapy effectiveness.

Alkaptonuria Severity and Ochronosis Assessment

Assesses alkaptonuria disease burden using urinary homogentisic acid excretion, ochronotic deposition severity, joint involvement, and cardiac valve disease to monitor nitisinone therapy response.

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Alkaptonuria Severity and Ochronosis Assessment

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Frequently Asked Questions

What causes ochronosis in alkaptonuria?

How does nitisinone treat alkaptonuria?

What joints are most commonly affected in alkaptonuria?

What clinical signs suggest alkaptonuria diagnosis?

What monitoring is needed with nitisinone therapy?