Renal tubular acidosis with deafness

Renal tubular acidosis with deafness is a disorder characterized by kidney (renal) problems and hearing loss. The kidneys normally filter fluid and waste products from the body and remove them in urine; however, in people with this disorder, the kidneys do not remove enough acidic compounds from the body. Instead, the acids are absorbed back into the bloodstream, and the blood becomes too acidic. This chemical imbalance, called metabolic acidosis, can result in a range of signs and symptoms that vary in severity. Metabolic acidosis often causes nausea, vomiting, and dehydration; affected infants tend to have problems feeding and gaining weight (failure to thrive). Most children and adults with renal tubular acidosis with deafness have short stature, and many develop kidney stones.

The metabolic acidosis that occurs in renal tubular acidosis with deafness may also lead to softening and weakening of the bones, called rickets in children and osteomalacia in adults. This bone disorder is characterized by bone pain, bowed legs, and difficulty walking. Rarely, people with renal tubular acidosis with deafness have episodes of hypokalemic paralysis, a condition that causes extreme muscle weakness associated with low levels of potassium in the blood (hypokalemia).

In people with renal tubular acidosis with deafness, hearing loss caused by changes in the inner ear (sensorineural hearing loss) usually begins between childhood and young adulthood, and gradually gets worse. An inner ear abnormality affecting both ears occurs in most people with this disorder. This feature, which is called enlarged vestibular aqueduct, can be seen with medical imaging. The vestibular aqueduct is a bony canal that runs from the inner ear into the temporal bone of the skull and toward the brain. The relationship between enlarged vestibular aqueduct and hearing loss is unclear. In renal tubular acidosis with deafness, enlarged vestibular aqueduct typically occurs in individuals whose hearing loss begins in childhood.