Renal tubular acidosis is a disorder characterized by unusually high levels of acidity in the blood. It occurs when the kidneys are unable to remove enough acid from the body and expel it in urine. Several different symptoms can result, including chronic fatigue, muscle pains, heart palpitations, and poor growth in children. Without treatment, renal tubular acidosis can lead to permanent kidney damage and possibly kidney failure. Most cases of renal tubular acidosis can be corrected with medications and supplements designed to stabilize acid levels in the blood.
There are a few different varieties of renal tubular acidosis classified by the parts of the renal tubes they affect and the symptoms they cause. The most common type is called distal acidosis, referring to a problem with the final section of a tubule that normally secretes acid into the urine. Many cases of distal acidosis are inherited, but the disease can also arise in persons with sickle-cell anemia, liver cirrhosis, or an autoimmune disorder such as rheumatoid arthritis or lupus. Acid imbalances can lower blood potassium levels and lead to symptoms of unstable heart rate, muscle weakness, and kidney stones. Young children may develop rickets and fail to reach normal heights and weights as well.
Renal tubular acidosis can also arise because of problems with the proximal end of a tubule. Proximal acidosis raises blood acidity because too much basic fluid is filtered from the blood and expelled in urine. Like distal acidosis, the disease can be inherited or arise because of an immune system deficiency. Some patients who receive long-term chemotherapy for cancer treatment develop proximal acidosis as a complication. Symptoms typically include fatigue, appetite changes, and bone and muscle pain.
Doctors who suspect renal tubular acidosis can perform a series of diagnostic tests to learn about the severity, type, and causes of the disease. Blood and urine samples are screened thoroughly to determine their acid and potassium levels. If a physical defect in the kidney is suspected, imaging tests such as ultrasounds may be performed.
Both distal and proximal renal tubular acidosis are treated by increasing patients' intake of basic chemicals. Sodium bicarbonate, the active ingredient in baking soda, is the most commonly used supplement. People with acidosis may need to drink baking soda solutions or take bicarbonate pills daily to prevent symptoms from worsening. A potassium supplement may also be prescribed if blood-potassium levels are dangerously low. Regular exercise and frequent medical checkups are essential to help ensure that bone and kidney problems are getting better with treatment.
