Proximal renal tubular acidosis

Proximal renal tubular acidosis (pRTA) or type 2

The principal feature of Fanconi syndrome is bone demineralization (osteomalacia or rickets) due to phosphate and vitamin D wasting.

Signs and symptoms

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Causes

Etiologies of proximal RTA may be divided into primary, isolated causes and secondary causes, or those related to another disease.^[2] Primary causes are frequently single gene hereditary disorders. Secondary disorders can be divided into familial disorders, acquired disorders, and those related to other clinical entities.^{[citation needed]}

Primary Disorders

• Autosomal dominant
• Autosomal Recessive with Ocular Abnormalities (caused by
  SLC4A4
  mutation)
• Sporadic of Infancy (possibly related to immaturity of NHE-3)

Secondary Disorders

Familial disorders

• Cystinosis^[3]
• Galactosemia^[4]
• Glycogen storage disease (type I)^[5]
• Hereditary fructose intolerance^[6]
• Lowe syndrome^[7]
• Tyrosinemia
• Wilson's disease^[8]

Acquired disorders

• Amyloidosis^[9]
• Multiple myeloma^[10]
• Paroxysmal nocturnal hemoglobinuria^[11]
• Toxins, such as
  HAART, ifosfamide,^[12] lead, and cadmium

Diagnosis of proximal renal tubular acidosis is done by measuring the level of fractional excretion of bicarbonate in the urine. Since in proximal renal tubular acidosis patients the nephron is unable to reabsorb bicarbonate, the level of bicarbonate is going to be high in the urine.^[citation needed]

Treatment

Treatment consists of oral bicarbonate supplementation. However, this will increase urinary bicarbonate wasting and may well promote a bicarbonate diuresis. The amount of bicarbonate given may have to be very large to stay ahead of the urinary losses. Correction with oral bicarbonate may exacerbate urinary potassium losses and precipitate hypokalemia.^[13] As with dRTA, reversal of the chronic acidosis should reverse bone demineralization.^[14]

Thiazide diuretics can also be used as a treatment by making use of contraction alkalosis caused by them.^{[citation needed]}

See also

• Renal tubular acidosis
• Distal renal tubular acidosis

References