Kidney Tubular Acidosis

Without treatment and over time, acidity of the blood can lead to one or more of the following:

• Failure to thrive
• Kidney stones
• Bone disease
• Chronic kidney disease
• Acute kidney injury

There are four types of renal tubular acidosis:

• Type 1. Type 1 renal tubular acidosis—also called distal RTA—occurs relatively far from the beginning of the renal tubule (the part of the kidney where acid and waste products are removed from the blood). A main effect of distal RTA is low blood potassium levels, which can cause extreme weakness, irregular heartbeat, paralysis and, more rarely, death. Type 1 RTA can be inherited or a symptom of:
  • Analgesic nephropathy
  • Chronic active hepatitis
  • Chronic urinary tract infections
  • A hereditary form of deafness
  • Hyperparathyroidism
  • Hyperthyroidism
  • Lupus
  • Obstructive uropathy
  • Primary biliary cirrhosis
  • Rejection of a transplanted kidney
  • Renal medullary cystic disease
  • Sickle cell disease
  • Sjögren's syndrome
    
• Type 2. Type 2 renal tubular acidosis—also called proximal RTA—occurs closer to the beginning of the renal tubule. This type of RTA occurs more often in infants as part of a disorder called Fanconi syndrome (a disorder in which certain needed minerals are passed into the urine instead of being reabsorbed into the bloodstream). Proximal RTA can also occur as a symptom of some inherited disorders that keep the body from effectively breaking down and using nutrients. Examples of inherited disorders that can lead to proximal RTA include cystinosis (a condition in which the amino acid cystine builds up in the body and damages cells) and Wilson's disease.
• Type 3. Type 3 renal tubular acidosis is considered to be a combination of Type 1 RTA and Type 2 RTA.
• Type 4. Type 4 renal tubular acidosis—also called hyperkalemic RTA—occurs when a part of the kidney called the distal tubule fails to move electrolytes from the blood to the urine, causing a buildup of electrolytes in the blood. Hyperkalemic RTA can happen if there is a deficiency of the hormone aldosterone or the distal tubule fails to respond to aldosterone. This type of RTA can also occur as a side effect of the use of certain medicines such as diuretics, blood pressure medicines, antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs), anticoagulants and immunosuppressants. Hyperkalemic RTA can also be caused by a variety of conditions that affect kidney structure and function such as:
  • Diabetic nephropathy
  • Human immunodeficiency virus (HIV)
  • Addison’s disease
  • Sickle cell disease
  • Urinary tract obstruction
  • Lupus
  • Amyloidosis
  • Removal or obstruction of both adrenal glands
  • Kidney transplant rejection

Diagnosis of Kidney Tubular Acidosis

In order to diagnose kidney tubular acidosis, your child's doctor may perform the following tests:

• Blood test. A blood test can check the acid-base balance in your child's blood. If the blood contains more acid than it should, renal tubular acidosis could be the underlying cause. The amount of potassium in the blood can also tell the doctor which type of RTA your child has. 
• Urinalysis. A urinalysis can check the acid-base balance in your child's urine. If the urine contains less acid than it should, renal tubular acidosis could be the underlying cause. The amount of sodium, potassium and chloride in the urine can also tell the doctor which type of RTA your child has.
• Renal ultrasound. Some forms of RTA can cause calcium deposits in the kidneys, such as stones. A kidney ultrasound will show this.