Renal Tubular Acidosis Type I

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Contents 1 More Specific Terms 2 Etiology 3 Epidemiology 4 Pathology 5 Genetics 6 Clinical-manifestations 7 Laboratory 8 Radiology 9 Management 10 More General Terms 11 References

More Specific Terms

• distal renal tubular acidosis with deafness
• distal renal tubular acidosis with preserved hearing (RTADR)

Etiology

• defect in distal nephron acidification
• *hypercalciuria may be the cause of RTA I
• associated conditions:

• autoimmune disorders

• Sjogren's syndrome
• rheumatoid arthritis
• primary biliary cirrhosis
• systemic lupus erythematosus

• hypergammaglobulinemia/ multiple myeloma
• genetic disorders

• Ehlers-Danlos syndrome
• Marfans syndrome
• hereditary elliptocytosis

• disorders associated with nephrocalcinosis

• primary hyperthyroidism
• hypervitaminosis D
• idiopathic hypercalcuria

• renal tubulointerstitial disease

• obstructive uropathy 2[ renal transplantation

• volume depletion (marked)
• drugs

• amphotericin B
• lithium
• ifosfamide
• toluene sniffing

• hyperkalemic form associated with:

• obstructive uropathy
• sickle-cell nephropathy
• systemic lupus erythematosus

• hepatic cirrhosis
• idiopathic

Epidemiology

• more common than type II RTA
• less common than type IV RTA

Pathology

• papillary nephrocalcinosis
• hypercalciuria may be the cause of RTA I
• inability to lower urine pH normally; reduced renal H+ excretion

Genetics

• autosomal recessive form(s)
• autosomal dominant form

Clinical-manifestations

• osteomalacia ( rickets) most severe of all the RTA's
• frequent musculoskeletal complaints ( hypokalemia)
• periodic paralysis
• growth retardation

Laboratory

• metabolic acidosis

• HCO3- 5-15 meq/L
• normal anion gap
• hypokalemia
• hyperchloremia

• urine pH:

• inappropriately high
• > 5.5 (pH < 5.5 excludes RTA-1)

• serum aldosterone normal to high
• low 24 hour urine citrate

• citrate is an inhibitor of nephrocalcinosis ( urolithiasis)

• no aminoaciduria
• hypercalciuria*
• hyperphosphaturia

Radiology

• punctate renal calcifications may be seen on plain radiographs *hypercalciuria may be the cause of RTA I.

Management

• correction of K+ deficit (hypokelemia) first [3]

• potassium citrate may useful for treatment of nephrocalcinosis

• bicarbonate replacement (1-2 meq/kg/day)

• this may correct Ca+2-wasting & osteomalacia

More General Terms

• renal tubular acidosis (RTA)

References

1. Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995
2. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 602-603, 616, 620
3. Medical Knowledge Self Assessment Program (MKSAP) 11, 15, American College of Physicians, Philadelphia 1998, 2009
4. Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 1324

renal tubular acidosis (RTA) type I (hyperchloremic acidosis)