First AIDFIRST AI DOCTORYour care companion
Health library/Alkaptonuria

Rare metabolic disorders / RARE CONDITION

Alkaptonuria

Also known as: AKU, Alcaptonuria, Homogentisic acid oxidase deficiency, Homogentisic acidura

Alkaptonuria causes accumulation of a substance that darkens urine and connective tissues. Over time, pigment buildup can damage joints and other tissues.

Save to my health notebook +

Save after unlocking your private notebook. An article bookmark does not add a diagnosis.

What you may notice

Symptoms can overlap with other conditions and vary between people.

  • Urine darkening after standing
  • Dark pigmentation
  • Back or joint pain
  • Kidney stones in some people

Understanding care

Clinical care may include metabolic evaluation and monitoring of joints, kidneys and other complications. A qualified clinician decides which investigations and options fit the individual situation.

When to seek help

Seek specialist review for new or progressive organ-related symptoms. Sudden severe pain, breathing difficulty, confusion or collapse requires urgent assessment.

For severe breathing difficulty, collapse, suspected stroke, or another emergency, call local emergency services immediately. In India, call 112.

Read the medical sources

These sources support the educational article and offer more detail.

Educational reading · Updated 6 October 2026

Prepared from the linked sources. This summary has not had an independent clinician review. A qualified clinician can assess symptoms and explain which information applies to you.

A child and a caring grown-up reading a picture book together

LITTLE PEOPLE. BIG FEELINGS.

It’s okay to have
a lot of questions.

A doctor visit or an unfamiliar health word can feel scary. You can ask a trusted grown-up to help you understand, one small question at a time.

01

Say how you feel.

“I feel worried” is a good place to start.

02

Ask for simple words.

“Can you explain that in a way I understand?”

03

Bring someone you trust.

A caring adult can help you ask and listen.

For children and their grown-ups. This illustration explains a conversation, not a diagnosis. An adult should seek qualified care for a child who is unwell.

Alkaptonuria — First AID health library