Term
| Type II RTA - decreased threshold for proximal tubule bicarbonate resorption |
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Definition
| - urine pH appropriately low (<5.3) --> distal tubule still able to acidify urine - UAG negative - UOG >100 (high since [NH4+] >50) - causes: a. isolated: mutations in NBC1 or acetazolamide-induced b. Fanconi's syndrome - generalized prox tubule defect - urinary phosphate wasting, urate wasting and glycosuria - associations: Lowe's syndrome cystinosis galactosemia tyrosinemia Wilson's disease methylmalonic acidemia hereditary fructose intolerance pyruvate carboxylase deficiency meds/toxins: Ifosfamide, outdated tetracycline, lead, cadmium, mercury |
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Term
Type I RTA
- impaired acid excretion in the distal tubule with concomitant hypokalemia |
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Definition
- urine pH inappropriately high (>5.3)
- UAG positive
- UOG <100
- causes:
1. defects in H-ATPase in the cortical collecting duct
a. congenital - genetic defects (associated with deafness)
b. acquired - Sjogren's
2. defects in anion exchanger 1 (AE1) - associated with hemolytic anemia
3. increased membrane permeability and H+ backleak - amphotericin
- associated hypercalciuria and nephrocalcinosis from reduced TRPV6 (Calcium channel) activity in distal tubule |
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Term
Type IV RTA
- impaired acid excretion with concomitant hyperkalemia |
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Definition
- causes:
1. defects in aldosterone - hypoaldosteronism, pseudohypoaldosteronism (AD: mineralocorticoid receptor defect, AR: ENaC deficiency)
- urine pH appropriately low (<5.3)
- UAG positive and UOG <100 (because total acid excretion reduced due to lack of urinary buffer excretion or NH4+)
2. urinary tract obstruction
- urine pH high (>5.3)
- UAG positive, UOG low (total acid excretion also reduced) |
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