E72.11

HCC Category Mapping

What This Code Means

A rare genetic disorder where the body cannot properly break down the amino acid methionine, leading to elevated homocysteine levels in blood and urine.

Coding Tips

• •Document whether this is classic homocystinuria or a variant form, as treatment approaches differ
• •This condition requires lifelong management and monitoring; ensure documentation reflects ongoing care

Clinical Significance

Homocystinuria (classic form due to cystathionine beta-synthase deficiency) causes accumulation of homocysteine and methionine in blood and urine, leading to significant vascular risk including thromboembolism, lens subluxation (ectopia lentis), skeletal abnormalities (Marfanoid habitus), and intellectual disability. The condition is classified as B6-responsive or B6-nonresponsive, which directly impacts treatment approach. Early diagnosis and treatment significantly improve outcomes.

Documentation Requirements

• ✓Document plasma homocysteine and methionine levels, pyridoxine (vitamin B6) responsiveness testing results, ophthalmologic examination for lens subluxation, history of thromboembolic events, skeletal findings, intellectual assessment, and current treatment regimen (pyridoxine, betaine, methionine-restricted diet).
• ✓Record genetic testing results for CBS mutations.

Commonly Confused Codes