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renal tubular disease
Etiology:
1) hereditary disorders (see hereditary renal tubular defects)
2) acquired disorders
a) renal tubular acidosis type IV (RTA-4)
b) oncogenic osteomalacia
3) pharmaceuticals nephrotoxic to renal tubules
a) antibiotics
- aminoglycoside antibiotics
- amphotericin B
- pentamidine
- foscarnet
- tenofovir
b) intravenous contrast agents
c) NSAIDs
d) chemotherapeutic agents
- cisplatin, carboplatin
- ifosfamide
4) exposure to toxins
- renal tubular injury may occur via chronic interstitial nephritis
- aristolochic acid
- germanium
- heavy metals: lead
Pathology:
1) patterns of renal tubular injury [1]
a) tubular proteinuria < 1.5-2 g/day
b) proximal tubule dysfunction
- hypokalemia
- hypouricemia
- hypophosphatemia
- acidosis
- glycosuria
- aminoaciduria
c) distal tubule dysfunction
- hyperchloremic acidosis*
- hyperkalemia or hypokalemia
- salt wasting
d) medullary concentration dysfunction
- nephrogenic diabetes insipidus with decreased urine concentrating ability
e) azotemia (renal insufficiency)
2) transport dysfunction of renal tubular injury [2]
a) reduced GFR*
- obliteration of vasculature
- obstruction of renal tubules
b) Fanconi syndrome
- impaired proximal tubular reabsorption of glucose, amino acids, phosphate & bicarbonate
c) hyperchloremic acidosis*
- reduced ammonia production
- inability to acidify collecting duct fluid (distal renal tubular acidosis)
- proximal tubular bicarbonate wasting
d) tubular or low-molecular weight proteinuria*
- defect is proximal tubular protein reabsorption
e) polyuria, isosthenuria*
f) hyperkalemia*
- K+ secretory defects
- aldosterone resistance
g) salt wasting
- distal tubular damage
- failure of Na+ reabsorption
* common
Laboratory:
1) urinalysis
a) urine sediment)
- pyuria
- leukocyte casts
- urine eosinophils
- hematuria
b) urine protein (tubular proteinuria)
c) aminoaciduria
d) glycosuria
2) serum chemistries
- BUN, creatinine -> azotemia
- serum K+ -> hyperkalemia
- hypouricemia
- hypophosphatemia
- acidosis
Interactions
disease interactions
Specific
acute tubular necrosis; tubulorrhexis (ATN)
hereditary renal tubular defects
medullary sponge kidney disease
proximal tubulopathy
pyelonephritis
renal tubular acidosis (RTA)
renal tubular dysgenesis
General
tubulointerstitial nephropathy
References
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed)
Lippincott-Raven, Philadelphia, 1998
- Harrison's Principles of Internal Medicine, 13th ed.
Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 1314,
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