Renal Tubular Acidosis Type Iv

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

Etiology

• acquired condition generally caused by insufficient urinary buffers, generally NH3
• disorders of aldosterone metabolism (> 98% are associated with diabetes mellitus)

• hyporeninemic hypoaldosteronism
• resistance to aldosterone
• isolated aldosterone deficiency

• congenital enzyme deficiency

• Addison's disease
• pharmacologic agents

• low renin, low aldosterone

• NSAIDs
• beta-blockers
• cyclosporine A
• tacrolimus

• high renin, low aldosterone

• heparin
• ACE inhibitors
• angiotensin II receptor antagonists
• ketoconazole

• aldosterone receptor antagonists

• amiloride
• spironolactone
• triamterene
• trimethoprim
• pentamidine
• eplerenone

• lithium

• chronic tubulointerstitial nephritis

• analgesic abuse
• allergic interstitial nephritis
• chronic pyelonephritis
• sickle cell disease
• medullary cystic disease
• Sjogren's syndrome
• lupus erythematosus
• sarcoidosis
• tuberculosis
• leprosy
• hypertensive nephrosclerosis
• obstructive uropathy
• renal transplant patients

Epidemiology

• most common form of RTA

Pathology

• insufficient urinary buffers, generally NH3
• reduced H+ & K+ secretion
• azotemia

Clinical-manifestations

• no osteomalacia
• no nephrolithiasis

Laboratory

• Urine pH: < 5.5 (usually)
• serum HCO3-: > 15 meq/L
• serum aldosterone normal, high or low
• hyperkalemia
• normal 24 hour urine citrate
• generally decreased glomerular filtration rate
• azotemia (increased BUN & creatinine)

Radiology

• abdominal ultrasound if obstructive uropathy is suspected

Management

• rule out obstructive uropathy - foley catheter
• correct hyperkalemia [3]

• K+ restriction to 40-60 meq/day & a loop diuretic
• kayexelate may be necessary
• HCO3- 1.5-2.0 meq/kg/day may be required
• Fludrocortisone ( Florinef) 0.1-0.2 mg PO QD should be considered in patients with primary adrenal insufficiency
• stop ACE inhibitor

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 603, 625
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 IV