II. Pathophysiology

  1. Kidney unable to excrete daily acid load
  2. Results in Metabolic Acidosis

IV. Labs

  1. Chemistry Panel
    1. Serum Chloride elevated
    2. Serum bicarbonate decreased
    3. Anion Gap normal
  2. Arterial Blood Gas (ABG)
    1. Non-Anion Gap Metabolic Acidosis
  3. Fractional Excretion of Bicarbonate
    1. FE-HCO3 <5%: Distal RTA
    2. FE-HCO3 >15%: Proximal RTA
      1. Assumes serum bicarbonate >20 meq/L
  4. Urine Anion Gap (obtain urine Electrolytes)
    1. Urine Anion Gap = Urine Sodium + Urine Potassium - Urine Chloride
    2. Decreased or Normal Urine Anion Gap <-10
      1. Extrarenal (e.g. Diarrhea, TPN) Non-Anion Gap Metabolic Acidosis
      2. Appropriate renal ammonia excretion
    3. Increased Urine Anion Gap >+10
      1. Renal Non-Anion Gap Metabolic Acidosis
      2. Impaired renal ammonia excretion (e.g. Renal Tubular Acidosis)

V. Evaluation

  1. Step 1: Lab findings suggestive of Renal Tubular Acidosis (RTA)
    1. Non-Anion Gap Metabolic Acidosis AND
    2. Urine Anion Gap Positive
      1. Negative Urine Anion Gap suggests gastrointestinal losses
  2. Step 2: Serum Potassium
    1. Low or normal: Go to Step 3
    2. High Serum Potassium
      1. Type IV Renal Tubular Acidosis
      2. Aldosterone Deficiency
  3. Step 3: Urine pH
    1. High Urine pH >5.3
      1. Type I Renal Tubular Acidosis (Distal RTA, Classic RTA)
    2. Low or normal Urine pH (or variable Urine pH)
      1. Type II Renal Tubular Acidosis (Proximal RTA)

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Related Studies

Ontology: Renal tubular acidosis (C0001126)

Definition (NCI) Failure of the renal tubules of the kidney to excrete urine of normal acidity resulting in metabolic acidosis. It may lead to hypercalcinuria, nephrolithiasis, and renal failure. Causes include autoimmune disorders (e.g., Sjogren syndrome, systemic lupus erythematosus, and rheumatoid arthritis), medications (e.g., non steroidal anti-inflammatory drugs, diuretics, and blood pressure medications), Fanconi syndrome, or it may be familiar.
Definition (NCI_NCI-GLOSS) A rare disorder in which structures in the kidney that filter the blood are impaired, producing urine that is more acid than normal.
Definition (CSP) rare sometimes familial disorder of the renal tubule characterized by the inability to excrete urine of normal acidity; this leads to a hyperchloremic acidosis which is often associated with one or more secondary complications such as hypercalcinuria with nephrolithiasis and nephrocalcinosis, rickets, or osteomalacia and severe potassium depletion.
Definition (MSH) A group of genetic disorders of the KIDNEY TUBULES characterized by the accumulation of metabolically produced acids with elevated plasma chloride, hyperchloremic metabolic ACIDOSIS. Defective renal acidification of URINE (proximal tubules) or low renal acid excretion (distal tubules) can lead to complications such as HYPOKALEMIA, hypercalcinuria with NEPHROLITHIASIS and NEPHROCALCINOSIS, and RICKETS.
Concepts Disease or Syndrome (T047)
MSH D000141
ICD10 N25.89
SnomedCT 1776003
English Acidosis, Renal Tubular, renal tubule acidosis, RENAL ACIDOSIS TUBULAR, Renal Tubular Acidosis, renal tubular acidosis (diagnosis), renal tubular acidosis, Acidosis renal tubular, Renal acidosis tubular, RTA, Renal tubular acidosis NOS, Acidosis, Renal Tubular [Disease/Finding], acidosis renal tubules, rta, acidosis tubular renal, tubular renal acidosis, RTA - Renal tubular acidosis, Renal tubular acidosis (disorder), tubular acidosis; renal, RTA, NOS, Renal tubular acidosis, NOS, Renal tubular acidosis
Spanish ACIDOSIS TUBULAR RENAL, ATC, Acidosis de los Túbulos Renales, Acidosis Renal Tubular, acidosis tubular renal (trastorno), acidosis tubular renal, Acidosis tubular renal, Acidosis Tubular Renal
Italian Acidosi renale tubulare, Acidosi renale ipercloremica, Incidente stradale, Acidosi tubulare renale, Acidosi tubolare renale
Dutch acidose renaal tubulair, verkeersongeluk, renale acidose tubulair, tubulusacidose; renaal, niertubulus acidose, Acidose, renale tubulaire, Klassieke renale tubulaire acidose, RTA, Renale tubulaire acidose, Tubulaire acidose, renale
French Acc de la circ, Acidose des tubules rénaux, ATR (Acidose Tubulaire Rénale), ACIDOSE RENALE ORIGINE TUBULAIRE, Acidose rénale hyperchlorémique, Acidose tubulaire rénale
German Azidose renal tubulaer, RTA, AZIDOSE NEPHROGEN, renaltubulaere Azidose, Azidose, renale tubuläre, Renale tubuläre Azidose
Portuguese Acidente de viação, Acidose renal tubular, ACIDOSE RENAL TUBULAR, Acidose dos Túbulos Renais, Acidose Renal Tubular, Acidose tubular renal, Acidose Tubular Renal
Japanese 交通事故, ジンニョウサイカンセイアシドーシス, コウツウジコ, ニョウサイカンセイアシドーシス, アシドーシス-腎尿細管性, 尿細管性アシドーシス, 腎尿細管性アシドーシス, 一過性遠位尿細管性アシドーシス, Lightwood症候群, アシドーシス-尿細管性
Swedish Acidos, renal tubulär
Finnish Renaalinen tubulaarinen asidoosi
Russian ATSIDOZ POCHECHNYI KANAL'TSEVYI, POCHECHNYI KANAL'TSEVYI ATSIDOZ, АЦИДОЗ ПОЧЕЧНЫЙ КАНАЛЬЦЕВЫЙ, ПОЧЕЧНЫЙ КАНАЛЬЦЕВЫЙ АЦИДОЗ
Czech Renální tubulární acidóza, Dopravní nehoda, acidóza renální tubulární, renální tubulární acidóza
Polish Kwasica nerkowa kanalikowa, Kwasica kanalikowa
Hungarian Közúti közlekedési baleset, renalis tubularis acidosis, Renalis tubularis acidosis
Norwegian Renal tubulær acidose