Distal Renal Tubular Acidosis

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Overview, Causes, & Risk Factors

When healthy, your body is very slightly alkaline. Acidic substances in the body, such as carbon dioxide, are buffered (counteracted) by alkaline substances, primarily bicarbonate. Your kidneys regulate your body's pH by controlling acids and bicarbonate buffer.

An acidic state in your body can be caused by high carbon dioxide levels (respiratory alkal). It can also be caused by low bicarbonate levels (metabolic acidosis).

Distal renal tubular acidosis (Type I RTA) is a disorder caused by a defect in the secretion of hydrogen ions in the distal renal tubule of each nephron. This reduces the reabsorption of bicarbonate into the bloodstream.

Type I RTA is caused by a variety of conditions including hereditary disorders, autoimmune diseases and certain drugs including amphotericin B, lithium, and analgesics.

Renal tubular acidosis causes disorders related to the loss of bicarbonate and inability to excrete hydrogen. The body attempts to maintain a balance between positively charged and negatively charged molecules. If the excretion of a molecule is abnormal, the excretion of other molecules may become abnormal in an attempt to maintain a balance.

Type I RTA causes retention of acid and is also associated with mild loss of potassium in the urine.

The acidic condition of the body causes calcium to dissolve from the bones. The calcium accumulates in the bloodstream, and excess serum calcium is excreted by the kidneys, causing a loss of total body calcium and resulting in osteomalacia or rickets, impaired growth of children, skeletal deformities, and muscle weakness.

There is an increased incidence of kidney stones and nephrocalcinosis associated with the excessive excretion of calcium and phosphate through the kidneys.