Serum Bicarbonate (HCO 3 ) is used as a buffer for the retained H+
(HCO 3 +H+ ---> H 2 CO 3 ----> H 2 O + CO 2 ), so its blood level will be low
in metabolic acidosis. As the proximal convoluted tubular function is intact
in distal RTA, more HCO 3 and chloride (CL-) will be reabsorped from its
lumen. Reabsorped HCO 3 will be used for buffering more H+.
Etiology:
- Primary
- idiopathic
- genetic (autosomal dominant)
- Autoimmune disease
- SLE
- Sjogren's Syndrome
- Chronic active hepatitis
- Tubulo-interstitial disease
- Chronic pyelonephritis
- Acute tubular necrosis
- Obstructive uropathy
- Renal transplant glomerulopathy
- Drugs and toxins
- Analgesics • Amphotericin B
- Lithium • Toluene
- Uretero-sigmoidostomy
Clinical Features: