Renal Tubular Acidosis


But too much acid in the blood—acidosis—can disturb many bodily functions.
urine and returning bicarbonate—an alkaline, or base, substance—to the blood.
food is broken down in the body.


One researcher, pediatric neurologist Donald Lewis, has theorized that
would likely have included sodium bicarbonate and sodium citrate, which are
treatment can indeed reverse the effects of RTA.


different underlying causes of acidosis.

Types of RTA

At one time, doctors divided RTA into four types.



    blood enter the tubule.



  • Type 3 is rarely used as a classification today because it is now thought to
    be a combination of type 1 and type 2.


  • Type 4 RTA is caused by another defect in the distal tubule, but it is
    potassium is important in regulating heart rate.

Type 1: Classic Distal RTA

(systemic diseases), like the autoimmune disorders Sjögren’s syndrome and

Other diseases and conditions associated with distal RTA include
hyperparathyroidism, a hereditary form of deafness, analgesic nephropathy,
rejection of a transplanted kidney, renal medullary cystic disease, obstructive
uropathy, and chronic urinary tract infections.

A major consequence of classic distal RTA is low blood-potassium. The level
drops if the kidneys excrete potassium into urine instead of returning it to the
blood supply. Since potassium helps regulate nerve and muscle health and heart
rate, low levels can cause extreme weakness, cardiac arrhythmias, paralysis, and
even death.

Untreated distal RTA causes growth retardation in children and progressive
renal and bone disease in adults. Restoring normal growth and preventing kidney
stones, another common problem in this disorder, are the major goals of therapy.
If acidosis is corrected with sodium bicarbonate or sodium citrate, then low
blood-potassium, salt depletion, and calcium leakage into urine will be
corrected. Alkali therapy also helps decrease the development of kidney stones.
Potassium supplements are rarely needed except in infants, since alkali therapy
prevents the kidney from excreting potassium into the urine.

Type 2: Proximal RTA

called Fanconi’s syndrome. The symptoms of Fanconi’s syndrome include high
vitamin D deficiency and low blood-potassium.

Proximal RTA can also result from inherited disorders that disrupt the body’s
normal breakdown and use of nutrients. Examples include the rare disease
cystinosis (in which cystine crystals are deposited in bones and other tissues),
hereditary fructose intolerance, and Wilson’s disease.

Proximal RTA also occurs in patients treated with ifosfamide, a drug used in
chemotherapy. A few older drugs—such as acetazolamide or outdated
tetracycline—can also cause proximal RTA. In adults, proximal RTA may complicate
diseases like multiple myeloma, or it may occur in people who experience chronic
rejection of a transplanted kidney.

When possible, identifying and correcting the underlying causes are important
steps in treating the acquired forms of proximal RTA. The diagnosis is based on
the chemical analysis of blood and urine samples. Children with this disorder
would likely receive large doses of oral alkali, such as sodium bicarbonate or
potassium citrate, to treat acidosis and prevent bone disorders, kidney stones,
and growth failure. Correcting acidosis and low potassium levels restores normal
growth patterns, allowing bone to mature while preventing further renal disease.
Vitamin D supplements may also be needed to help prevent bone problems.

Type 4: Hyperkalemic RTA


Hyperkalemic distal RTA may result from sickle cell disease, urinary tract
obstruction, lupus, amyloidosis, or transplantation.

Aldosterone’s action may be impeded by drugs, including

  • diuretics used to treat congestive heart failure such as spironolactone or
  • blood pressure drugs called angiotensin-converting enzyme (ACE) inhibitors
    and angiotensin receptor blockers (ARBs)
  • the antibiotic trimethoprim
  • an agent called heparin that keeps blood from clotting
  • the antibiotic pentamidine, which is used used to treat pneumonia
  • a class of painkillers called nonsteroidal anti-inflammatory drugs
  • some immunosuppressive drugs used to prevent transplant

For people who produce aldosterone but cannot use it, researchers have no

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