This process is called ochronosis (as the tissue looks ochre); ochronotic tissue is stiffened and unusually brittle, impairing its normal function and causing damage. Diagnosis
If the diagnosis of alkaptonuria is suspected, it can be confirmed or excluded by collecting urine for 24 hours and determining the amount of homogentisic acid by means of chromatography. No assay of HGA in blood has been validated. The Genetic Testing Registry  is used for maintaining information about the genetic test for alkaptonuria.The severity of the symptoms and response to treatment can be quantified through a validated questionnaire titled the AKU Severity Score Index. This  assigns scores to the presence of particular symptoms and features, such as the presence of eye and skin pigmentation, joint pain, heart problems, and organ stones. Treatment
No treatment modality has been unequivocally demonstrated to reduce the complications of alkaptonuria. Main treatment attempts have focused on preventing ochronosis through the reduction of accumulating homogentisic acid. Such commonly recommended treatments include large doses of ascorbic acid (vitamin C) or dietary restriction of amino acids phenylalanine and tyrosine. However, vitamin C treatment does not have definitively proven effectiveness and protein restriction (which can be difficult to adhere to) has not shown to be effective in clinical studies.Several studies have suggested that the herbicide nitisinone may be effective in the treatment of alkaptonuria. Nitisinone inhibits the enzyme 4-hydroxyphenylpyruvate dioxygenase, responsible for converting tyrosine to homogentisic acid, thereby blocking the production and accumulation of HGA.
Nitisinone has been used for some time at much higher doses in the treatment of type I tyrosinemia. Nitisinone treatment has been shown to cause a larger than 95% reduction in plasma and urinary HGA. The main drawback is accumulation of tyrosine, the long-term risks of which are unknown; a particular concern exists about damage to the cornea of the eye. Long-term use requires frequent monitoring for complications. Prognosis
Alkaptonuria does not appear to affect life expectancy, although the latest study on the topic is from 1985. The main impact is on quality of life; many people with alkaptonuria have disabling symptoms such as pain, poor sleep, and breathing symptoms. These generally start in the fourth decade. The typical age at requiring joint replacement surgery is 50–55 years. Epidemiology
In most ethnic groups, the prevalence of alkaptonuria is between 1:100,000 and 1:250,000. In Slovakia and the Dominican Republic, the disease is much more common, with prevalence estimated at 1:19,000 people. As for Slovakia, this is not the result of a single mutation, but due to a group of 12 mutations in specific "hot spots" of the HGD gene. The Slovakian clustering probably arose in a small area in the northwest of the country and spread after the 1950s due to migration. History
Alkaptonuria was one of the four diseases described by Archibald Edward Garrod, as being the result of the accumulation of intermediates due to metabolic deficiencies.