Difference between revisions of "Renal tubular acidosis"

(Text replacement - "==Differential==" to "==Differential Diagnosis==")
(Etiologies)
 
(5 intermediate revisions by the same user not shown)
Line 1: Line 1:
 
==Background==
 
==Background==
*Hyperchloremic metabolic acidosis, non-anion gap
+
*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
 
*Diagnostic classification starts with low, normal, or high serum potassium
 
*Differentiate from [[uremia]] in which acidosis is anion gap
 
*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==
 
==Etiologies==
Line 20: Line 10:
 
**[[Amyloidosis]]
 
**[[Amyloidosis]]
 
**Drugs - ifosfamide, [[acetazolamide]]
 
**Drugs - ifosfamide, [[acetazolamide]]
**Heavy metals ([[Lead]], mercury, copper/Wilson's)
+
**Heavy metals ([[Lead]], [[mercury toxicity|mercury]], [[copper toxicity|copper]]/[[wilson's disease|Wilson's]])
**Vitamin D deficiency, rickets, hypophosphatemia
+
**[[Vitamin D deficiency]], [[rickets]], [[hypophosphatemia]]
 
**[[Paroxysmal nocturnal hemoglobinuria]]
 
**[[Paroxysmal nocturnal hemoglobinuria]]
**Renal transplant
+
**[[kidney transplant|Renal transplant]]
 
**Fanconi's syndrome
 
**Fanconi's syndrome
 
**Familial
 
**Familial
 
**Primary metabolic (cystinosis, von Gierke's)
 
**Primary metabolic (cystinosis, von Gierke's)
 
*Type I RTA
 
*Type I RTA
**Autoimmune - [[Sjogren's]], [[SLE]], [[RA]]
+
**Autoimmune - [[Sjögren]], [[SLE]], [[RA]]
 
**Drugs - [[Lithium]], [[amphotericin B]], ifosfamide
 
**Drugs - [[Lithium]], [[amphotericin B]], ifosfamide
 
**[[Sickle cell disease]]
 
**[[Sickle cell disease]]
 
**[[Cirrhosis]]
 
**[[Cirrhosis]]
 
**Obstructive uropathy
 
**Obstructive uropathy
**Renal transplant
+
**[[kidney transplant|Renal transplant]]
 
**Familial (decreased H+/K+-ATPase, Na+/K+-ATPase activity)
 
**Familial (decreased H+/K+-ATPase, Na+/K+-ATPase activity)
 
*Type IV RTA
 
*Type IV RTA
 
**Aldosterone deficiency or resistance
 
**Aldosterone deficiency or resistance
**Diabetic nephropathy (hyporenin/hypoaldosteronism)
+
**[[DM|Diabetic nephropathy]] (hyporenin/hypoaldosteronism)
 
**Obstructive uropathy
 
**Obstructive uropathy
 
**Chronic tubulointerstitial disease
 
**Chronic tubulointerstitial disease
**Potassium-sparing diuretics
+
**Potassium-sparing [[diuretics]]
**Heparin induced adrenal insufficiency
+
**[[Heparin]] induced [[adrenal insufficiency]]
 +
 
 +
==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
  
 
==Features and Treatment==
 
==Features and Treatment==
*Mild acidosis in adults with bicarb > 20 mEq/L may not require Tx
+
*Mild acidosis in adults with bicarb > 20 mEq/L may not require treatment
 
*Children should be treated due to impaired growth
 
*Children should be treated due to impaired growth
 
*For type I and II RTA, treat all children and infants
 
*For type I and II RTA, treat all children and infants
 
**Generally, 5-15 mEq/kg/day oral bicarbonate
 
**Generally, 5-15 mEq/kg/day oral bicarbonate
**May require IV bicarbonate for severe acidosis
+
**May require IV [[bicarbonate]] for severe acidosis
**PO potassium supplements
+
**PO [[potassium]] supplements
 
**Treat adults with bicarb < 18-20 mEq/L
 
**Treat adults with bicarb < 18-20 mEq/L
 
**Treat underlying d/o (Vitamin D, etc.)
 
**Treat underlying d/o (Vitamin D, etc.)
Line 75: Line 76:
 
**Urine pH < 5.5
 
**Urine pH < 5.5
 
*Serum aldosterone and cortisol levels to determine between:
 
*Serum aldosterone and cortisol levels to determine between:
**Adrenal insufficiency, Addison's (low aldosterone, low cortisol)
+
**[[Adrenal insufficiency]], [[addison's disease|Addison's]] (low aldosterone, low cortisol)
 
**Selective aldosterone deficiency (low aldosterone, normal cortisol)
 
**Selective aldosterone deficiency (low aldosterone, normal cortisol)
 
**Aldosterone resistance (nl to high aldosterone, nl to high cortisol)
 
**Aldosterone resistance (nl to high aldosterone, nl to high cortisol)

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