renal tubular disease Flashcards
what is renal tubular acidosis?
Impaired acid excretion → hyperchloraemic met acidosis
Both → RAS activation → K+ wasting and hypokalaemia
what are the types of renal tubular acidosis?
type 1- distal
type 2- proximal
what is type 1 renal tubular disease?
distal
inability to excrete H+ even when acidotic
may complicate other renal disorders
what are the causes of type 1 renal tubular disease?
Hereditary: Marfan’s, Ehler’s Danlos
AI: Sjogren’s, SLE, thyroiditis
Drugs
what are the features of type 1 renal tubular disease?
Rickets / osteomalacia (bone buffering)
Renal stones and UTIs
Nephrocalcinosis → ESRF
how is type 1 renal tubular acidosis diagnosed?
failure to acidify urine ph>5.5 despite acid load
what is type 2 renal tubular acidosis?
proximal
Defect in HCO3 reabsorption in PCT
Tubules can reabsorb some HCO3 so can acidify urine in
systemic acidosis when HCO3 ↓
Usually associated w Fanconi syndrome
how do you diagnose type 2 renal tubular acidosis?
urine will acidify with acid load pH<5.5
what is fanconi syndrome?
Disturbance of PCT function → generalised impaired reabsorption
amino acids, K+, HCO3, phosphate, glucose
what are the causes of fanconi syndrome?
Idiopathic
Inherited: inborn errors, Wilson’s
Acquired: tubule damage - drugs, myeloma
what are features of fanconi syndrome?
Polyuria (osmotic diuresis)
Hypophosphataemic rickets (Vit D resistant)
Acidosis, ↓K
what are hereditary hypokalaemic tubulopathies?
bartter’s syndrome
gitelman syndrome
what is bartter’s syndrome?
Blockage of NaCl reabsorption in loop of Henle (as if taking frusemide)
Congenital salt wasting → RAS activation → hypokalaemia and metabolic alkalosis
Normal BP
what is giltelman syndrome?
blockage of nacl reabsorption in DCT as if taking thiazides
congenital salt wasting -> RAS activation -> hypokalaemia + metabolic acidosis + hypocalciuria
normal BP
