Renal Tubular Acidosis Flashcards
what is RTA?
where there is a metabolic acidosis due to pathology in the tubules of the kidney
(tubules responsible for balancing hydrogen and bicarbonate ions - and maintaining normal pH)
4 types of RTA
type 1+4 are most likely to come up
Type 1 renal tubular acidosis: where does it occur and what causes it
Pathology in the distal tubule - it is unable to excrete hydrogen ions
Causes:
- Genetic. There are both autosomal dominant and recessive forms.
- Systemic lupus erythematosus
- Sjogren’s syndrome
- Primary biliary cirrhosis
- Hyperthyroidism
- Sickle cell anaemia
- Marfan’s syndrome
Presentation of type 1 RTA:
Presentation:
- Failure to thrive in children
- Hyperventilation to compensate for the metabolic acidosis
- Chronic kidney disease
- Bone disease (osteomalacia)
Lab findings in type 1 RTA
- hypokalaemia
- Metabolic acidosis
- high urinary pH (above 6)
Treatment for type 1 RTA:
Oral bicarbonate - this corrects other electrolyte imbalances
type 2 RTA: where does it occur
Due to pathology in the proximal tubule
Proximal tubule is unable to reabsorb bicarbonate from the urine and blood
- therefore excessive bicarbonate is excreted in the urine
Main cause of t2 RTA
Fanconi’s syndrome
Lab results in t2 TRA:
Hypokalaemia
Metabolic acidosis
High urinary pH (above 6)
Treatment of t2 rta
Oral bicarbonate
Type 3 RTA (all)
Combination of t1+2 RTA - pathology in proximal and distal tubule
Rare and unlikely to appear in exams or clinical practice
T4 RTA - pathophys
(most common RTA)
Caused by reduced aldosterone
Can be due to:
- Adrenal insufficiency
- medications -> (ACE inhib/ spironolactone)
- Systemic conditions affecting kidneys
- SLE
- DM
- HIV
T4 RTA - lab findings:
Hyperkalaemia
High chloride
Metabolic acidosis
Low urinary pH
Management of t4 RTA
- Fludrocortisone
Sodium bicarbonate + treatment of hyperkalemia may also be required
