Renal Tubular Acidosis
Renal tubular acidosis (RTA) occurs when the kidneys do not remove acids from the blood into the urine as they should. The acid level in the blood then becomes too high, a condition called acidosis. Some acid in the blood is normal, but too much acid can disturb many bodily functions.
Causes
Type 1 RTA may be inherited.
Researchers have identified at least three different genes that may cause the inherited form of the disease.
2 People with sickle cell anemia external link or Ehlers-Danlos syndrome, which are also inherited, may develop type 1 RTA later in life.
Type 2 RTA may be inherited or caused by other inherited conditions such as
Cystinosis external link, a rare disease in which cystine crystals are deposited in bones and other tissues
Hereditary fructose intolerance external link
Wilson disease
Type 4 RTA can also occur when diseases or an inherited disorder affect how the kidneys work, such as
Addison’s disease, due to disease or removal of the adrenal glands external link
Congenital adrenal insufficiency
Aldosterone synthase deficiency external link
Gordon syndrome external link
Amyloidosis
Diabetic kidney disease
HIV/AIDS
kidney transplant rejection
Lupus
Sickle cell disease external link
Urinary tract obstruction
Types
There are three main types of RTA.
Type 1 RTA, or distal RTA, occurs when there is a problem at the end or distal part of the tubules.
Type 2 RTA, or proximal RTA, occurs when there is a problem in the beginning or proximal part of the tubules.
Type 4 RTA, or hyperkalemic RTA, occurs when the tubules are unable to remove enough potassium, which also interferes with the kidney’s ability to remove acid from the blood.
Type 3 RTA is rarely used as a classification now because it is thought to be a combination of type 1 and type 2 RTA.
Symptoms
The major signs of type 1 RTA and type 2 RTA are low levels of potassium and bicarbonate a waste product produced by your body in the blood. The potassium level drops if your kidneys send too much potassium into your urine instead of returning it to the blood.
Because potassium helps regulate your nerve and muscle health and heart rate, low potassium levels can cause
Extreme weakness
Irregular heartbeat
Paralysis external link
Death The major signs of type 4 RTA are high potassium and low bicarbonate levels in the blood. Symptoms of type 4 RTA include9
Abdominal pain external link
Fatigue external link that does not go away
Weak muscles
Not feeling hungry
Weight change
Diagnosis
Your health care professional will review your medical history and order blood external link and urine tests external link to measure the levels of acid, base, and potassium in your blood and urine.
If your blood is more acidic than it should be and your urine is less acidic than it should be, RTA may be the reason, but a health care professional will need to rule out other causes.
Treatment
For all types of RTA, drinking a solution of sodium bicarbonate external link or sodium citrate will lower the acid level in your blood.
This alkali therapy can prevent kidney stones from forming and make your kidneys work more normally so kidney failure does not get worse.
Infants with type 1 RTA may need potassium supplements, but older children and adults rarely do because alkali therapy prevents the kidneys from excreting potassium into the urine.
Children with type 2 RTA will also drink an alkali solution (sodium bicarbonate or potassium citrate) to lower the acid level in their blood, prevent bone disorders and kidney stones, and grow normally.
Some adults with type 2 RTA may need to take vitamin D supplements to help prevent bone problems.
People with type 4 RTA may need other medicines to lower the potassium levels in their blood.
If your RTA is caused by another condition, your health care professional will try to identify and treat it.