Renal tubular disease Flashcards
What is renal tubular acidosis (RTA)
Impaired acid excretion → hyperchloraemic met acidosis Both → RAS activation → K+ wasting and hypokalaemia
What is Type 1
Inability to excrete H+, even when acidotic May complicate other renal disorders
Causes of Type 1
Hereditary: Marfan’s, Ehler’s Danlos
AI: Sjogren’s, SLE, thyroiditis
Drugs
Features of Type 1
Rickets / osteomalacia (bone buffering)
Renal stones and UTIs
Nephrocalcinosis → ESRF
Differential feature
Failure to acidify urine (pH >5.5) despite acid load
What is type 2?
Defect in HCO3 reabsorption in PCT
Tubules can reabsorb some HCO3 so can acidify urine in
systemic acidosis when HCO3 ↓
Usually assoc. ̄c Fanconi syndrome
Differential feature of type 2
Urine will acidify ̄c acid load (pH <5.5)
What is Fanconi syndrome
Disturbance of PCT function → generalised impaired reabsorption
amino acids, K+, HCO3, phosphate, glucose
Causes of Fanconi syndrome?
Idiopathic
Inherited: inborn errors, Wilson’s
Acquired: tubule damage (drugs, myeloma…)
Features of Fanconi syndrome
Polyuria (osmotic diuresis) Hypophosphataemic rickets (Vit D resistant) Acidosis, ↓K
Name 2 hereditary hypokalaemic tubulopathies?
Bartter’s syndrome
Gitelman syndrome
What is Bartter’s syndrome
Bartters syndrome is a combination of juxtaglomerular hyperplasia, hyperaldosteronism and hypokalaemic, hypochloraemic alkalosis often with hypercalciuria. It is autosomal recessive. There is reduced sodium and chloride absorption and excessive aldosterone production resulting in the biochemical abnormalities. It can lead to renal stones due to the hypercalciuria
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 Gitelman syndrome
Blockage of NaCl reabsorption in DCT (as if taking thiazides)
Congenital salt wasting → RAS activation → hypochloremic metabolic alkalosis, hypokalemia, and hypocalciuria and hypomagnesemia
Normal BP
