RTAs

Question 1

RTA

Answer 1

A net decrease in either tubular H secretion or HCO3 reabsorption that leads to a non-anion gap metabolic acidosis. Type 4 (distal) is the most common form

Question 2

Type 1 (distal) RTA

Answer 2

Defect: H secretion

1) Low serum K
2) urine pH above 5.3
3) Causes: hereditary, cirrhosis, AI disorders (sjogren, SLE), hypercalciuria, sickle cell, drugs (lithium, amphotericin)
4) Tx: replace HCO3
5) Complication: Nephrolithiasis

Question 3

Type 2 (proximal) RTA

Answer 3

Defect: HCO3 reabsorption

1) Low serum K
2) urine pH 5.3 initially then less when serum is acidic
3) Causes: Hereditary (Fanconi or cystinosis), drugs (carbonic anhydrase inhibitors), multiple myeloma, amyloidosis, heavy metal poisoning, vit D deficiency
4) Tx: Thiazides, volume depletion to increase reabsorption.
5) Complications: Rickets, osteomalacia

Question 4

Type 4 (distal) RTA

Answer 4

Defect: Aldosterone deficiency or resistance

1) HIGH SERUM K
2) Low urine pH below 5.3
3) Causes: Primary aldosterone deficiency, hyporeninemic hypoaldosteronism (from kidney disease, ACEIs, NSAIDs), drugs (amiloride, spironolactone, heparin), pseudo-hypoaldosteronism
4) Tx: Furosemide, mineralocorticoid plus minus glucocorticoird replacement
5) Complication: HyperK