What Is Black Urine: Causes, Diagnosis,Treatment & Prevention


We all may be aware of different shades of urine like yellow, dark yellow, red or brown, but, the term 'black urine' sounds scary, doesn't it? Black urine is the darkest of all urine colours, and this could be due to several causes. While the intake of certain foods or medications may cause a temporary change in colour of the urine, black urine can also occur due to an underlying health condition. This article explains the causes, diagnosis, treatment and prevention of black urine disease.

The Black Urine disease is also referred to as 'alkaptonuria' or 'black bone disease', is a genetic metabolic disorder. A typical sign of this condition is that the urine turns black in colour when left standing for some time.

The causes of black urine could be food, few health conditions, and consumption of medicines. Discussed below are some of the major causes of black urine:

1. Food-related changes
2. Medicines
3. Health Issues
4. Alkaptonuria
5. Poisoning

If the change in your urine colour is due to food, it is not a cause for concern, as once you avoid consuming that particular food, the colour of urine returns to normal. Often, if the reason is food, you would have consumed a considerable portion of food that contains natural or artificial dyes, or a food that may have reacted chemically with your urine, causing the dark brown or black colour of the urine.

If food is not the cause of the black colour in your urine, then another possibility could be the medicines that you may be using. The medicinal causes could be dependent on the medications that you are taking, or if you are taking too many medications for a prolonged period of time. You can discuss with your doctor to check if medicines are the reason behind your condition.

When food or medicines are the causes of black urine, you may consider avoiding the use of that particular food or try using an alternative medicine. However, if they are not the cause, then certain underlying health conditions such as 'alkaptonuria' may be the cause, so you should consider seeking an appointment with your doctor.

Alkaptonuria is a rare genetic metabolic disorder, which can cause black urine. It is caused due to a defective gene named HGD that is responsible for the breakdown of amino acids named 'phenylalanine' and 'tyrosine' which help in building up of proteins. In this condition, due to some mutations in the HGD gene, the normal functioning of the enzyme homogentisate 1,2-dioxygenase is hindered. As a result, an intermediate product namely homogentisic acid gets accumulated in the blood and tissues. Homogentisic acid, and its oxidised form, alkapton are excreted through urine, which makes the colour of urine black.

Although a very rare occurrence, black urine, may be caused due to mixing up of certain medications and alcohol, for instance. This is a poisoning-like condition, and is not a direct cause of the body, but, the body may experience difficulty processing the chemicals within, leading to the chaos.

As young adults, the patients with this condition may be asymptomatic, other than their urine turning inky black when left exposed to air. However, with time, there may be some associated signs and symptoms with this condition such as:

• Pigmentation may be noticed around the ear and eye
• Adults may develop pain in hips, knees and spine joints
• Bone mineral density may be affected
• Irregularities in heart rhythm may be seen in some people
• Organ stones, particularly, kidney stones, gallstones, prostate stones and salivary gland stones may occur.

Doctors may advise you to test for this condition if your urine turns black or dark brown when exposed to air. A blood test may be performed for the screening of gene mutation. They may also test if you develop an early onset of osteoarthritis.

In case black urine disease is suspected, this is confirmed by collecting the urine sample, and leaving it for twenty-four hours to determine the amount of Homogentisic Acid (HGA) through chromatography. Sometimes, other accompanying scores and signs such as the presence of eye and skin pigmentation, joint pains, heart problems are also taken into consideration for diagnosis of the condition.

• There is no clear treatment suggested to reduce complications of black urine disease or alkaptonuria. But, you may have to go on a low-protein diet and may be recommended high dosages of Vitamin C to slow down the accumulation of the HGA in your cartilage.

• Other treatments may include prevention or alleviation of associated complications like heart disease, arthritis, kidney stones, and prescription of anti-inflammatory medicines.

• Physical and occupational therapy may help in improving the flexibility of your joints and muscles and strengthening them.

• Rarely, patients with black urine disease or alkaptonuria may require a surgery of the knee, or hip replacement, or a surgery of heart valves if they stop functioning properly. In some cases, you may require surgeries to treat kidney or prostate stones.

• Most complications of black urine disease can be delayed or prevented with regular check-ups. In case you observe dark coloured urine in young children or infants, it should be immediately evaluated.

• In case you have a family history of the condition, prenatal tests can help in detecting the condition early.

• Your doctor may monitor you regularly and suggest tests like spinal X-rays to check for spinal degeneration and calcification, chest X-rays to monitor your heart valves, and CT scans to check for signs of coronary artery disease.

• Generally, following a healthy lifestyle by incorporating a balanced meal, restricting high protein intake, and doing regular exercises can be of help when tackling this health condition.

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