RTA

60 y/o pt presented with Polyuria, polydypsia...only abnormal finding is serum potassium 2.19 and hco3 12 and low ph----------------------------so pt is hving metabolic acidosis and AG is normal....
so two possibilities

1. GI loss
2. RTA

So now have to check Urine PH and Urine AG and Urine K+------------His Urine PH is 5 , UAG positive and urine k+ 30 which is > 25 MEq/l--------------


Type 1 RTA : Decrease H+ secretion from Distal Tubule. Most common cause is Autoimmune disorder Sjogren syndrome
Type 2 RTA: Decrease HCO3 reabsorption from PT .. mcc is multiple myeloma , carbonic anhydrase Inhibitor
Type 4 RTA: Hypoaldosteronism  so increase K+

this pt is having low K+ so obviously this ppt is not hving type 4 RTA....
so differentiate Type 1 vs Type 2 RTA----------give NaHCO3-----------type 1 will response and U HCO3 will be low while in type 2 coz of decreased HCO3 reabsorption ---------urine HCO3 will be high and blood PH also wont have much effect....

Treatment :
type 1: give NaHCO3,  K citrate
Type 2: Give NaHCO3( but wont have much effect coz of abnormal PT), so add  thiazide, K+ citrate
Type 4: give mineralo corticoid----fludrocortisone +/- cortisol , also add diuretic for edema.