Causes Of Proximal Renal Tubular Acidosis

Proximal renal tubular acidosis is a form of metabolic acidosis characterized by decreased ability of proximal tubules to resume glomerular filtrate bicarbonate.
Causes of proximal renal tubular acidosis

Proximal renal tubular acidosis is  caused by the loss of too much of the body’s bicarbonate. The kidneys also do not excrete enough of the body’s acid.

The common feature of this condition is the reduced ability of the proximal tubules to resume glomerular filtrate bicarbonate.

Its prevalence is unknown. However, proximal renal tubular acidosis arising from drugs is relatively common. Inherited proximal renal tubular acidosis is very rare.

Symptoms of proximal renal tubular acidosis

Kidneys illustrate proximal renal tubular acidosis

The symptoms of this condition depend on the underlying disease or disorder. This condition causes rapid breathing, lethargy and confusion. Additionally, it can lead to shock and even death.

It first manifests as very alkaline urine due to the unabsorbed bicarbonate. It also causes low growth and a decrease in bone mineral density.

In some cases, hypokalaemia may occur and some symptoms of periodic paralysis may also manifest. English patients and osteomalacia,  however, are due to lack of vitamin D and lack of phosphate uptake.


Kidney diseases such as distal renal tubular acidosis and proximal renal tubular acidosis  can cause hyperchloremic acidosis.

It can also manifest in case of poisoning with aspirin, ethylene glycol or methanol. Violent dehydration can also lead to this condition.

People can get or inherit this condition either recessively (in most cases) or dominantly. When one acquires renal acidosis, it is caused by a mutation in the SLC4A4 gene.

However, dominant acidosis is caused by mutations in a gene that have not yet been identified. Since the proximal tubules resume about 80% of the amount of filtrate bicarbonate, a lack of it leads to a loss of bicarbonate.

Some types of medication may have been responsible  for the development of proximal renal tubular acidosis, which is not inherited.

Diagnosis of proximal renal tubular acidosis

Doctor with kidney

Unlike patients with distal renal tubular acidosis, patients with proximal renal tubular acidosis retain the  ability to lower the pH of the urine below 5.5.

To diagnose the disease, professionals must prove lack of bicarbonate resumption. A bicarbonate titration test confirms a diagnosis of proximal renal tubular acidosis.

In the study, an excessive increase in the excretion of urine bicarbonate occurs when plasma bicarbonate rises above the limit of the kidney.

Medical professionals should also rule out other inherited proximal tubule disorders,  such as oculocerebrotenal syndrome, dent disease, and glycogen storage disease due to GLUT2 deficiency.

Regarding blood tests, a doctor may require a sample of arterial blood gas and a test of electrolytes to confirm renal hyperchloremic acidosis.

In addition, they may require a comprehensive metabolic test consisting of a group of blood samples that measure the levels of sodium and potassium,  as well as the levels of other chemicals. Later, they will measure the pH of the urine, levels of ketone in urine and blood and the level of lactic acid.

This set of tests can also help determine if the cause of acidosis is a condition associated with breathing or a metabolic problem.


Doctor holds model of kidneys

Treatment depends on the cause of the disease. Inherited renal tubular acidosis requires lifelong therapy with bicarbonate replacement.

To perform this treatment, doctors need large amounts of bicarbonate to normalize bicarbonate.

Sometimes  medical professionals prescribe thiazide diuretics, such as hydrochlorothiazide  (25-50 mg a day) to increase bicarbonate uptake and thus reduce the amount of bicarbonate needed.

It is also important to monitor potassium plasma, which is why a mixture of sodium and potassium bicarbonate salts may be necessary in some cases.

Usually, proximal renal acidosis caused by medication is recoverable upon discontinuation of the medication. With proper treatment, the  prognosis for this condition is good.

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