Renal tubular acidosis

Alkali replacement therapy is given to correct metabolic acidosis and to maintain serum potassium levels in the normal range.

Dose of alkali begins at 1 mEq/kg and is increased as needed to achieve normal serum bicarbonate. Severe potassium deficits should be at least partially corrected before beginning bicarbonate administration.

Any one of many solutions may be used. Shohl solution is generally the most accepted. Potassium-containing variants of Shohl solution should be used when there is a significant potassium deficit.

Consult specialist for further guidance on dose.

Treatment recommended for SOME patients in selected patient group

Classic distal RTA typically presents with significant potassium deficits and ongoing potassium losses in the urine.

Owing to the effects of hypokalemia on cardiac rhythm and nerve and muscle function, attempts should be made to correct potassium balance to normal (e.g., potassium supplements).

The serum potassium should be checked at intervals and therapy adjusted as needed. Although unlikely to occur, over-replacement or too rapid replacement could result in hyperkalemia. Infusion rates of >10 mEq/hour should be used with caution in patients with extremely low potassium levels.

Treatment is intended to correct acidosis and to maintain a serum bicarbonate concentration at a near-normal level.[4]Rodriguez Soriano J. Renal tubular acidosis: the clinical entity. J Am Soc Nephrol. 2002 Aug;13(8):2160-70. http://jasn.asnjournals.org/content/13/8/2160.full http://www.ncbi.nlm.nih.gov/pubmed/12138150?tool=bestpractice.com [141]Domrongkitchaiporn S, Khositseth S, Stitchantrakul W, et al. Dosage of potassium citrate in the correction of urinary abnormalities in pediatric distal renal tubular acidosis patients. Am J Kidney Dis. 2002 Feb;39(2):383-91. http://www.ncbi.nlm.nih.gov/pubmed/11840381?tool=bestpractice.com A large amount of bicarbonate is usually required to correct the acidosis.[4]Rodriguez Soriano J. Renal tubular acidosis: the clinical entity. J Am Soc Nephrol. 2002 Aug;13(8):2160-70. http://jasn.asnjournals.org/content/13/8/2160.full http://www.ncbi.nlm.nih.gov/pubmed/12138150?tool=bestpractice.com

Potassium excretion is increased by bicarbonaturia; therefore, a combination of sodium and potassium salts is often used to treat this disorder.

If serious hypokalemia is present it may be necessary to replete potassium stores before giving large doses of alkali.

Consult specialist for further guidance on dose.

Treatment recommended for SOME patients in selected patient group

Treatment is given when hypokalemia is evident. If patients have hypokalemia before the start of alkali treatment, potassium should be given first, because increasing the serum bicarbonate will increase bicarbonaturia and potassium excretion in the urine.

Potassium supplementation is also needed when hydrochlorothiazide is used as an adjunctive treatment.

Infusion rates of >10 mEq/hour should be used with caution in patients with extremely low potassium levels.

Treatment recommended for SOME patients in selected patient group

The defect in proximal bicarbonate reabsorption in proximal RTA is profound. Simply replacing alkali by oral supplementation can be very difficult because of the unpalatable nature of the solutions used.

Hydrochlorothiazide has been used as a supplemental treatment. It, or any other thiazide diuretic, can be used to induce a state of volume contraction, which, in turn, stimulates overall proximal reabsorption. Proximal bicarbonate reabsorption increases as overall proximal reabsorption increases. This effect helps to raise the serum bicarbonate.

However, the state of volume contraction induced by thiazide diuretics stimulates aldosterone secretion and increases the distal nephron secretion of potassium. Thus potassium losses worsen and may result in severe hypokalemia and potassium depletion. Potassium supplementation is always required when thiazides are used in proximal RTA.

There is no specific treatment for this type of RTA.

Alkali replacement therapy is given to correct metabolic acidosis and to maintain serum potassium levels in the normal range as required.

Severe potassium deficits should be at least partially corrected before beginning bicarbonate administration.

Any one of many solutions may be used. Shohl solution is generally the most accepted. Potassium-containing variants of Shohl solution should be used when there is a significant potassium deficit.

Consult specialist for further guidance on dose.

Treatment recommended for SOME patients in selected patient group

There is no specific treatment for this type of RTA, but if there is a potassium deficit, additional supplementation of potassium may be needed. Infusion rates of >10 mEq/hour should be used with caution in patients with extremely low potassium levels.

In some patients, correction of potassium deficit may improve ammonia production to the point that acidosis improves significantly.

Drugs known to be associated with hyperkalemia should be discontinued.

Patients should avoid salt substitutes containing potassium and should follow a low-potassium diet.

Fludrocortisone should be given (with caution in special situations such as the need to avoid mineralocorticoid administration to patients with congestive heart failure or hypertension).

When the serum potassium level is controlled there will often be an associated improvement in the acidosis by increasing ammonium excretion.

In patients with hypertension, heart failure, or advanced age the use of fludrocortisone may result in excessive sodium retention and exacerbation of hypertension or edema. Potassium level should be monitored.

Treatment is lifelong.

Treatment recommended for SOME patients in selected patient group

Alkali administration may be needed if correction of mineralocorticoid deficiency and potassium balance do not restore the serum bicarbonate to normal.

Consult specialist for further guidance on dose.

Patients should avoid salt substitutes and drugs containing potassium and should follow a low-potassium diet.

In these patients the aim is to increase urinary potassium loss by using loop diuretics, which directly inhibit potassium reabsorption in the loop of Henle.

Potassium losses due to the diuretic can be increased further if sodium in the diet is not restricted or even encouraged. However, because many of these patients are older and have some degree of renal insufficiency, their blood pressure and state of sodium balance must be monitored relatively closely.

Attention must be paid to the patient's volume status. Volume depletion and volume overload should both be avoided. Potassium level should be monitored.

Treatment recommended for SOME patients in selected patient group

In addition to the measures to correct potassium balance, patients may also need to take alkali solutions to improve acid-base balance.

Potassium-containing solutions should be avoided; thus Shohl solution is the primary therapy here and should be titrated until serum bicarbonate is normal.

Consult specialist for further guidance on dose.