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Distal renal tubular acidosis
Definition
Distal renal tubular acidosis is a disease that occurs when the kidneys don't remove acid properly into the urine, leaving the too much acid in the blood (called acidosis).
Alternative Names
Renal tubular acidosis - distal; Renal tubular acidosis type I; Type I RTA; RTA - distal; Classical RTA
Causes
When your body performs its normal functions, it produces acid. If this acid is not removed or neutralized, your blood will become too acidic. This can lead to electrolyte imbalances in the blood.
Your kidneys normally help control the acid level in your body by removing acids from the blood and sending them into the urine.
Distal renal tubular acidosis (Type I RTA) is caused by a defect in the kidney tubes that causes acid to build up in the bloodstream.
Type I RTA is caused by a variety of conditions, including:
- Amyloidosis
- Fabry disease
- High blood calcium
- Sickle cell disease
- Sjogren syndrome
- Systemic lupus erythematosus
- Wilson disease
- Use of certain drugs such as amphotericin B, lithium, and analgesics
Symptoms
- Confusion or decreased alertness
- Fatigue
- Impaired growth
- Increased breathing rate
- Kidney stones
- Nephrocalcinosis
- Osteomalacia
- Rickets
- Muscle weakness
Other symptoms can include:
- Bone pain
- Decreased urine output
- Increased heart rate or irregular heartbeat
- Muscle cramps
- Pain in the back, flank, or abdomen
- Skeletal abnormalities
Exams and Tests
Arterial blood gas and blood chemistries may suggest metabolic acidosis or electrolyte imbalances, most often low levels of potassium or bicarbonate.
Other tests that may be done include:
- Urine pH, usually greater than 5.3 in patients with this condition
- Urinalysis may show increased levels of calcium and potassium
Treatment
The goal is to restore the normal pH (acid-base level) and electrolyte balance. This will indirectly correct bone disorders and reduce the risk of calcium buildup in the kidneys (nephrocalcinosis) and kidney stones. The underlying cause should be corrected if it can be identified.
Alkaline medications such as potassium citrate and sodium bicarbonate correct the acidic condition of the body. Sodium bicarbonate may correct the loss of potassium and calcium.
Vitamin D and calcium supplements are usually not given because there may be calcium deposits in the kidneys, even after bicarbonate therapy.
Outlook (Prognosis)
The disorder must be treated to reduce its effects and complications, which can be permanent or life-threatening. Most cases get better with treatment.
Possible Complications
- Osteomalacia
- Rickets
- Nephrocalcinosis
- Kidney stones
- Electrolyte imbalances, such as low blood potassium level
When to Contact a Medical Professional
Call your health care provider if you have symptoms of distal renal tubular acidosis.
Get help immediately if you develop emergency symptoms, such as:
Prevention
There is no prevention for this disorder.
References
Seifter JL. Acid-base disorders. In: Goldman L, Schafer AI, eds.Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 120.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Herbert Y. Lin, MD, PHD, Nephrologist, Massachusetts General Hospital; Associate Professor of Medicine, Harvard Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
