RENAL SYSTEM
RENALTUBULAR ACIDOSIS
INTRODUCTION
 Lungs and Kidneys are responsible for Normal acid
base balance
 Alveolar ventilation removes CO2
 Kidneys...
DEFINITION
The term "renal tubular acidosis" (RTA)
refers to a group of disorders in
which, despite a relatively well-
pre...
INCIDENCE
 Predominant age: All ages
 Predominant sex: Male > Female (with
regard to type II RTA with isolated defect
in...
TYPES
 Distal / type 1 RTA
 Proximal / type 2 RTA
 Hypoaldosteronism / type 4 RTA
 Type 3 / mixed RTA (not in use)
Type 1-Distal RTA
Distal RTA (dRTA) is the classical form
of RTA. Inability of the distal tubule to
acidify the urine. Due...
PATHOPHYSIOLOGY
 failure of acid secretion by the alpha
intercalated cells of the cortical collecting
duct of the distal ...
RISK FACTORS
Genetics
Autosomal dominant or recessive. May
occur in association with other genetic
diseases (e.g., Ehlers-...
ETIOLOGY
• Genetic
• Sporadic
• Autoimmune diseases:
rheumatoid arthritis (RA), SLE
• Hematologic diseases:
Sickle cell di...
CLINICAL MANIFESTATIONS
 non-anion gap metabolic
acidosis
 growth failure
 nephrocalcinosis
 hypercalciuria
Defect of the proximal tubule in
bicarbonate (HCO3) reabsorption.
HCO3 fully reabsorbed only when
plasma HCO3 concentratio...
 It is caused by a failure of the proximal
tubular cells to reabsorb filtered
bicarbonate from the urine, leading to
urin...
Clinical manifestations -
phosphaturia, glycosuria, amin
oaciduria, uricosuria, and
tubular proteinuria. The
principal fea...
-Autosomal dominant form is rare.
-Autosomal recessive form is
associated with ophthalmologic
abnormalities and mental
ret...
 Diseases associated with Fanconi syndrome
 Sporadic
 Multiple myeloma & other dysproteinemic
states
 Amyloidosis
 He...
 growth failure in the 1st year of life
 polyuria
 dehydration
 anorexia
 vomiting
 constipation
 hypotonia
 Patie...
Type 3 RTA-Combined
proximal and distal RTA
Extremely rare autosomal recessive syndrome
with features of both type I and ...
Type 4 RTA
 Due to aldosterone resistance or deficiency
that results in hyperkalemia.
 It was included in the classifica...
RISK FACTORS
Some cases familial, such as
pseudohypoaldosteronism type
I (autosomal dominant)
ETIOLOGY
 Medications: Nonsteroidal anti-inflammatory
drugs, angiotensin-converting enzyme
inhibitors, angiotensin recept...
CLINICAL MANIFESTATIONS
 with growth failure in the first few years of
life
 Polyuria
 Dehydration
 Rarely, with life-...
History collection
 Often asymptomatic (particularly
type IV)
 Failure to thrive in children
 Anorexia, nausea/vomiting...
 Electrolytes - hyperchloremic metabolic
acidosis.
 Plasma anion gap normal (anion gap = Na - [Cl +
HCO3])
 Hypokalemia...
 Urine anion gap: Reflects unmeasured urine
anions, so inversely related to urine NH4+ (or
acid) excretion. Positive urin...
 correction of the acidemia with oral sodium
bicarbonate, sodium citrate or potassium citrate.
This will reverse bone dem...
 The base requirement for distal RTAs is generally in
the range of 2-4 mEq/kg/24 hr.
 Patients with Fanconi syndrome gen...
 Administration of sufficient bicarbonate to reverse
acidosis stops bone dissolution and the
hypercalciuria.
 Proximal R...
PROGNOSIS
• Depends on associated
disease, otherwise good with therapy
• Transient forms of all types of RTA
may occur.
COMPLICATIONS
• Nephrocalcinosis, nephrolithiasis
(type I)
• Hypercalciuria (type I)
• Hypokalemia (type I, type II if giv...
renal tubular acidosis (RTA)
renal tubular acidosis (RTA)
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renal tubular acidosis (RTA)

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metabolic acidosis develops because of defects in the ability of the renal tubules to perform the normal functions required to maintain acid-base balance.

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renal tubular acidosis (RTA)

  1. 1. RENAL SYSTEM RENALTUBULAR ACIDOSIS
  2. 2. INTRODUCTION  Lungs and Kidneys are responsible for Normal acid base balance  Alveolar ventilation removes CO2  Kidneys reabsorb filtered Bicarbonate and excrete a daily quantity of Hydrogen ion equal to that produced by the metabolism of dietary proteins.  Hydrogen ions are excreted primarily by enhancing the excretion of ammonium ions in the urine
  3. 3. DEFINITION The term "renal tubular acidosis" (RTA) refers to a group of disorders in which, despite a relatively well- preserved glomerular filtration rate, metabolic acidosis develops because of defects in the ability of the renal tubules to perform the normal functions required to maintain acid- base balance.
  4. 4. INCIDENCE  Predominant age: All ages  Predominant sex: Male > Female (with regard to type II RTA with isolated defect in bicarbonate reabsorption)
  5. 5. TYPES  Distal / type 1 RTA  Proximal / type 2 RTA  Hypoaldosteronism / type 4 RTA  Type 3 / mixed RTA (not in use)
  6. 6. Type 1-Distal RTA Distal RTA (dRTA) is the classical form of RTA. Inability of the distal tubule to acidify the urine. Due to impaired hydrogen ion secretion, increased backleak of secreted hydrogen ions, or impaired sodium reabsorption (causing less negative potential in the lumen and hence less hydrogen/potassium secretion).  Urine pH >5.5.
  7. 7. PATHOPHYSIOLOGY  failure of acid secretion by the alpha intercalated cells of the cortical collecting duct of the distal nephron.  it leads to an inability to acidify the urine to a pH <5.3  renal excretion is the primary means of eliminating acid from the body, there is consequently a tendency towards acidemia  There is an inability to excrete H+ while K+ cannot be reabsorbed, leading to acidemia (as H+ builds up in the body) and hypokalemia (as K+ cannot be reabsorbed).  the substance of the kidney develops stones bilaterally
  8. 8. RISK FACTORS Genetics Autosomal dominant or recessive. May occur in association with other genetic diseases (e.g., Ehlers-Danlos syndrome, hereditary elliptocytosis, or sickle cell nephropathy). The autosomal recessive form is associated with sensorineural deafness.
  9. 9. ETIOLOGY • Genetic • Sporadic • Autoimmune diseases: rheumatoid arthritis (RA), SLE • Hematologic diseases: Sickle cell disease, hereditary elliptocytosis • Medications: Amphotericin B, lithium, K+- sparing diuretics • Toxins: Toluene, glue • Hypercalciuria, diseases causing nephrocalcinosis • Vitamin D intoxication • Medullary cystic disease • Glycogenosis type III • Fabry disease • Wilson disease • Hypergammaglobulinemic syndrome • Obstructive uropathy • Chronic pyelonephritis • Chronic renal transplant rejection • Leprosy • Hepatic cirrhosis • Malnutrition
  10. 10. CLINICAL MANIFESTATIONS  non-anion gap metabolic acidosis  growth failure  nephrocalcinosis  hypercalciuria
  11. 11. Defect of the proximal tubule in bicarbonate (HCO3) reabsorption. HCO3 fully reabsorbed only when plasma HCO3 concentration <15–16 mEq/L (compared with normal threshold of 24 mEq/L). Urine pH <5.5 unless plasma HCO3 above reabsorptive threshold.
  12. 12.  It is caused by a failure of the proximal tubular cells to reabsorb filtered bicarbonate from the urine, leading to urinary bicarbonate wasting and subsequent acidemia.  The distal intercalated cells function normally, so the acidemia is less severe than dRTA and the urine can acidify to a pH <5.3.  it is usually associated with a generalized dysfunction of the proximal tubular cells called Fanconi's syndrome.
  13. 13. Clinical manifestations - phosphaturia, glycosuria, amin oaciduria, uricosuria, and tubular proteinuria. The principal feature of Fanconi's syndrome is bone demineralization due to phosphate wasting.
  14. 14. -Autosomal dominant form is rare. -Autosomal recessive form is associated with ophthalmologic abnormalities and mental retardation. Occurs in Fanconi syndrome, which is associated with several genetic diseases
  15. 15.  Diseases associated with Fanconi syndrome  Sporadic  Multiple myeloma & other dysproteinemic states  Amyloidosis  Heavy-metal poisoning  Medications: Acetazolamide, sulfanilamide, ifosfamide, o utdated tetracycline, topiramate  Autoimmune disease  Interstitial renal disease  Nephrotic syndrome  Congenital heart disease  Defects in calcium metabolism
  16. 16.  growth failure in the 1st year of life  polyuria  dehydration  anorexia  vomiting  constipation  hypotonia  Patients with primary Fanconi syndrome will have additional symptoms  Those with systemic diseases will present with additional signs and symptoms specific to their underlying disease
  17. 17. Type 3 RTA-Combined proximal and distal RTA Extremely rare autosomal recessive syndrome with features of both type I and type II (juvenile RTA). Combined dRTA and pRTA is also observed as the result of inherited carbonic anhydrase II deficiency. Mutations in the gene encoding this enzyme give rise to an autosomal recessive syndrome of osteopetrosis, renal tubular acidosis, cerebral calcification, and mental retardation. •
  18. 18. Type 4 RTA  Due to aldosterone resistance or deficiency that results in hyperkalemia.  It was included in the classification of renal tubular acidoses as it is associated with a mild (normal anion gap) metabolic acidosis due to a physiological reduction in proximal tubular ammonium excretion (impaired ammoniagenesis), which is secondary to hypoaldosteronism, and results in a decrease in urine buffering capacity.  Urine pH <5.5.
  19. 19. RISK FACTORS Some cases familial, such as pseudohypoaldosteronism type I (autosomal dominant)
  20. 20. ETIOLOGY  Medications: Nonsteroidal anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, heparin/LMW heparin, calcineurin inhibitors (tacrolimus, cyclosporine) (1)  Diabetic nephropathy  Obstructive nephropathy  Nephrosclerosis due to hypertension  Tubulointerstitial nephropathies  Primary adrenal insufficiency  Pseudohypoaldosteronism(end-organ resistance to aldosterone)  Gordon syndrome  Sickle cell nephropathy
  21. 21. CLINICAL MANIFESTATIONS  with growth failure in the first few years of life  Polyuria  Dehydration  Rarely, with life-threatening hyperkalemia  Patients with obstructive uropathies may present acutely with signs and symptoms of pyelonephritis  hyperkalemic non-anion gap metabolic acidosis  Alkaline or acidic urine  Elevated urine sodium levels & inappropriately low urine potassium levels reflect the absence of aldosterone effect.
  22. 22. History collection  Often asymptomatic (particularly type IV)  Failure to thrive in children  Anorexia, nausea/vomiting  Weakness or polyuria (due to hypokalemia)  Rickets in children  Osteomalacia in adults  Constipation  Polydipsia
  23. 23.  Electrolytes - hyperchloremic metabolic acidosis.  Plasma anion gap normal (anion gap = Na - [Cl + HCO3])  Hypokalemia or normokalemia  Hyperkalemia  Plasma HCO3 (in untreated RTA)  Blood urea nitrogen and creatinine usually normal (rules out renal failure as cause of acidosis)  Urine pH: Inappropriately alkaline (pH >5.5)  Urine culture: Rule out UTI with urea-splitting organism and chronic infection
  24. 24.  Urine anion gap: Reflects unmeasured urine anions, so inversely related to urine NH4+ (or acid) excretion. Positive urine anion gap in an acidemic patient indicates impaired renal acid excretion.  Urine calcium:  High in type I  Typically normal in type II  A renal ultrasound - to identify underlying structural abnormalities such as obstructive uropathies as well as to determine the presence of nephrocalcinosis.
  25. 25.  correction of the acidemia with oral sodium bicarbonate, sodium citrate or potassium citrate. This will reverse bone demineralization  Hypokalemia and urinary stone formation and nephrocalcinosis can be treated with potassium citrate tablets  Patients with proximal RTA often require large quantities of bicarbonate, up to 20 mEq/kg/24 hr in the form of sodium bicarbonate or sodium citrate solution
  26. 26.  The base requirement for distal RTAs is generally in the range of 2-4 mEq/kg/24 hr.  Patients with Fanconi syndrome generally require phosphate supplementation .  Patients with distal RTA should be monitored for the development of hypercalciuria. Symptomatic hypercalciuria, nephrocalcinosis, or nephrolithiasis may require thiazide diuretics to decrease urine calcium excretion.  Patients with type IV RTA may require chronic treatment for hyperkalemia with sodium-potassium exchange resin
  27. 27.  Administration of sufficient bicarbonate to reverse acidosis stops bone dissolution and the hypercalciuria.  Proximal RTA is treated with both bicarbonate and oral phosphate supplements to heal bone disease.  Vitamin D is needed to offset the secondary hyperparathyroidism that complicates oral phosphate therapy  The mainstay of therapy in all forms of RTA is bicarbonate replacement .
  28. 28. PROGNOSIS • Depends on associated disease, otherwise good with therapy • Transient forms of all types of RTA may occur.
  29. 29. COMPLICATIONS • Nephrocalcinosis, nephrolithiasis (type I) • Hypercalciuria (type I) • Hypokalemia (type I, type II if given bicarbonate) • Hyperkalemia (type IV, some causes of type I) • Osteomalacia (type II due to phosphate wasting)
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