Ver el código de «Renal tubular acidosis»

==Background==
*Hyperchloremic [[metabolic acidosis]], non-anion gap
*Diagnostic classification starts with low, normal, or high serum potassium
*Differentiate from [[uremia]] in which acidosis is anion gap

==Differential Diagnosis==
*See [[metabolic acidosis]]

==Workup==
*ABG or VBG
*BMP, phos, mag
*Urine pH
*Urine electrolytes - Na, K, Cl, Ca, Cr
*Plasma aldosterone and cortisol for type IV RTA
*Note that when hyperkalemia is present, aldosterone should be elevated, so a "normal" aldosterone level may be relatively low

==Etiologies==
*Type II RTA
**[[Multiple myeloma]]
**[[Amyloidosis]]
**Drugs - ifosfamide, [[acetazolamide]]
**Heavy metals ([[Lead]], mercury, copper/Wilson's)
**[[Vitamin D deficiency]], rickets, hypophosphatemia
**[[Paroxysmal nocturnal hemoglobinuria]]
**Renal transplant
**Fanconi's syndrome
**Familial
**Primary metabolic (cystinosis, von Gierke's)
*Type I RTA
**Autoimmune - [[Sjogren]], [[SLE]], [[RA]]
**Drugs - [[Lithium]], [[amphotericin B]], ifosfamide
**[[Sickle cell disease]]
**[[Cirrhosis]]
**Obstructive uropathy
**Renal transplant
**Familial (decreased H+/K+-ATPase, Na+/K+-ATPase activity)
*Type IV RTA
**Aldosterone deficiency or resistance
**Diabetic nephropathy (hyporenin/hypoaldosteronism)
**Obstructive uropathy
**Chronic tubulointerstitial disease
**Potassium-sparing diuretics
**Heparin induced adrenal insufficiency

==Features and Treatment==
*Mild acidosis in adults with bicarb > 20 mEq/L may not require treatment
*Children should be treated due to impaired growth
*For type I and II RTA, treat all children and infants
**Generally, 5-15 mEq/kg/day oral bicarbonate
**May require IV bicarbonate for severe acidosis
**PO potassium supplements
**Treat adults with bicarb < 18-20 mEq/L
**Treat underlying d/o (Vitamin D, etc.)

===Proximal Tubular Acidosis===
*Type II RTA - reduced bicarbonate reabsorption
**[[Hypokalemia]]
**Serum bicarb 12-20 mEq/L generally
**Urine pH < 5.5, but can be variable
*Urine pH > 5.5 if undergoing alkali therapy

===Distal Tubular Acidosis===
*Type I RTA - impaired H+ and ammonium secretion
**[[Hypokalemia]]
***Normokalemia may be seen in chronic interstitial renal disease
**Serum bicarb may be < 10 mEq/L
**Urine pH > 5.5
**Urinary anion gap > 50 mEq/L = Na + K - Cl
**[[Nephrolithiasis]], calcium stones from chronic acidosis causing bone resorption and hypercalciuria

===Type IV RTA===
*Also distal tubular acidosis
**[[Hyperkalemia]]
**Mild acidosis, with bicarb generally > 17 mEq/L
**Urine pH < 5.5
*Serum aldosterone and cortisol levels to determine between:
**Adrenal insufficiency, Addison's (low aldosterone, low cortisol)
**Selective aldosterone deficiency (low aldosterone, normal cortisol)
**Aldosterone resistance (nl to high aldosterone, nl to high cortisol)

==References==
*Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock. Renal Tubular Acidosis Syndromes. South Med J. 2000;93(11). http://www.medscape.com/viewarticle/410658.
*UCSF Education. Renal Tubular Acidosis. Nov 2002. https://medicine.ucsf.edu/education/resed/Chiefs_cover_sheets/renal%20tubular%20acidosis.pdf.
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