Proximal renal tubular acidos... Health Article

Definition

Proximal renal tubular acidosis is a condition that occurs when the kidneys don't properly remove acids in the urine, leaving the blood too acidic.

Alternative Names

Renal tubular acidosis - proximal; Type II RTA; RTA - proximal; Renal tubular acidosis type II

Causes, incidence, and risk factors

Your kidneys help regulate your body's acid-base balance (pH). Acidic substances in the body are buffered (counteracted) by alkaline substances, primarily bicarbonate.

The kidneys contain more than a million filtering units, called nephrons. Bicarbonate is reabsorbed into the blood in the nearest (proximal) tubule of each nephron. Proximal renal tubular acidosis (Type II RTA) occurs when bicarbonate isn't properly reabsorbed by the proximal tubules, leaving the body in an acidic state (called acidosis).

Type II RTA is less common than Type I RTA. It most often occurs during infancy, and may go away by itself.

Causes of type II RTA include:

• Cystinosis
• Drugs such as ifosfamide (a chemotherapy drug), outdated tetracycline, or acetazolamide
• Fanconi Syndrome
• Inherited fructose intolerance
• Wilson's disease

Symptoms

• Confusion or decreased alertness
• Dehydration
• Fatigue
• Increased breathing rate
• Osteomalacia
• Muscle pain
• Rickets
• Weakness

Other symptoms can include:

• Bloody urine
• Decreased urine output
• Increased heart rate or irregular heartbeat
• Muscle cramps
• Pain in the bones, back, flank, or abdomen
• Skeletal deformities

Signs and tests

• Arterial blood gas and blood chemistries may indicate metabolic acidosis and electrolyte abnormalities.
• Measurements of the blood pH and urine pH may show a problem. The urine may be alkaline, although this may change as the body becomes more acidic.
• Urinalysis may show abnormal levels of phosphate, calcium, glucose, and amino acids in the urine.

This disease may also change the results of the following tests:

• Acid loading test (pH
• Blood potassium level
• Urine calcium
• Urine citric acid
• Urine potassium level