Acidosis

The kidneys perform many vital functions, one of which is maintaining the proper balance of acids and alkali in the blood. Normally, the breakdown of food produces acids and alkali that circulate in the bloodstream. The kidneys then filter the acids from the blood and eliminate them in the urine. The kidneys usually do not filter the alkali, which are instead carried to the lungs and exhaled in the form of carbon dioxide. Renal tubular acidosis occurs when the kidney tubules malfunction and either do not remove enough acid or remove too much alkali from the blood.

Types and Causes of Renal Tubular Acidosis

There are four types of renal tubular acidosis:

• Type 1 (distal) RTA – Results from damage at the end of the kidney tubules, which may be inherited or associated with an autoimmune condition
• Type 2 (proximal) RTA – Results from damage at the base of the kidney tubules, which may be inherited, associated with Fanconi syndrome or multiple myeloma or caused by medication taken to treat HIV or viral hepatitis
• Type 3 RTA – Results from a combination of types 1 and 2
• Type 4 (hyperkalemic) RTA – Occurs when the kidney tubules are unable to remove enough potassium from the blood, which may result from low levels of the hormone aldosterone, a urinary obstruction or immunosuppressants taken after a kidney transplant

Symptoms of Renal Tubular Acidosis

Types 1, 2 and 3 RTA can cause low levels of potassium in the blood. Because potassium is a vital electrolyte that helps regulate the heart rate as well as the body’s nerve and muscle health, low potassium levels can cause:

• An irregular heartbeat
• Extreme weakness and fatigue
• Muscle twitching or cramping
• Diminished reflexes
• Kidney stones

Type 4 RTA can cause high levels of potassium in the blood (hyperkalemia), which can interfere with the kidney’s ability to remove acid from the blood and lead to:

• Heart palpitations or arrhythmia
• Chest or abdominal pain
• Nausea, vomiting or diarrhea
• Muscle weakness or numbness in the limbs

Diagnosis of Renal Tubular Acidosis

If renal tubular acidosis is suspected, a physician will likely order one or more diagnostic tests, such as:

• Anion gap – Measures the chemical balance of the blood
• Arterial blood gas – Measures the pH of the blood
• Urinalysis – Reveals the composition of the urine

Treatments for Renal Tubular Acidosis

A key component of treatment is addressing its underlying cause. If the proper blood pH balance is not restored, serious complications can develop, such as bone loss, kidney disease and diabetes.

In general, treatment may include:

• Oral or intravenous administration of sodium bicarbonate (a form of carbon dioxide) to help neutralize the acid in the blood
• Dietary changes to restrict potassium intake and avoid dehydration to help keep blood potassium levels in check

The renowned nephrology team at Tampa General Hospital offers a comprehensive range of treatment options for renal tubular acidosis and other types of kidney disease. Our goal is to help each patient achieve the best possible outcome and quality of life.