Difference between revisions of "Renal tubular acidosis"

(Etiologies)
 
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==Background==
 
==Background==
 +
*Class of disorders characterized by impaired reabsorption of filtered bicarbonate or excretion of hydrogen ions
 +
*Causes 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
  
==Sources==
+
==Etiologies==
 +
*Type II RTA
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**[[Multiple myeloma]]
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**[[Amyloidosis]]
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**Drugs - ifosfamide, [[acetazolamide]]
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**Heavy metals ([[Lead]], [[mercury toxicity|mercury]], [[copper toxicity|copper]]/[[wilson's disease|Wilson's]])
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**[[Vitamin D deficiency]], [[rickets]], [[hypophosphatemia]]
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**[[Paroxysmal nocturnal hemoglobinuria]]
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**[[kidney transplant|Renal transplant]]
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**Fanconi's syndrome
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**Familial
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**Primary metabolic (cystinosis, von Gierke's)
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*Type I RTA
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**Autoimmune - [[Sjögren]], [[SLE]], [[RA]]
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**Drugs - [[Lithium]], [[amphotericin B]], ifosfamide
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**[[Sickle cell disease]]
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**[[Cirrhosis]]
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**Obstructive uropathy
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**[[kidney transplant|Renal transplant]]
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**Familial (decreased H+/K+-ATPase, Na+/K+-ATPase activity)
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*Type IV RTA
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**Aldosterone deficiency or resistance
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**[[DM|Diabetic nephropathy]] (hyporenin/hypoaldosteronism)
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**Obstructive uropathy
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**Chronic tubulointerstitial disease
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**Potassium-sparing [[diuretics]]
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**[[Heparin]] induced [[adrenal insufficiency]]
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 +
==Differential Diagnosis==
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*See [[metabolic acidosis]]
 +
 
 +
==Workup==
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*[[ABG]] or [[VBG]]
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*BMP, phos, mag
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*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
 +
 
 +
==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]]
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**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
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**[[Hypokalemia]]
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***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===
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*Also distal tubular acidosis
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**[[Hyperkalemia]]
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**Mild acidosis, with bicarb generally > 17 mEq/L
 +
**Urine pH < 5.5
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*Serum aldosterone and cortisol levels to determine between:
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**[[Adrenal insufficiency]], [[addison's disease|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.
 
<references/>
 
<references/>
  
 
[[Category:FEN]]
 
[[Category:FEN]]

Latest revision as of 16:38, 29 September 2019

Background

  • Class of disorders characterized by impaired reabsorption of filtered bicarbonate or excretion of hydrogen ions
  • Causes 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

Etiologies

Differential Diagnosis

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

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