78 yo f presents with generalized weakness. Patient denies any complaints per se and was brought in by family member after patient could not answer her door due to her weakness. Vital signs were stable. Physical exam was unremarkable and she had not other ROS complaints.

Initial venous blood gas revealed pH of 7.21, pco2 40, lactate 2.1 and glucose of 20.

Initial ER venous revealed Na of 140, K 5.1, Cl 109, CO2 23, Bun 19, Cr 1.1 and glu 20.

Patient has a non-anion gap acidosis. Helpful mnemonic for differential in this category is HARDUP.

  • Hyperalimentation
  • Acetazolamide or other carbonic anhydrase inhibitors
  • Renal Tubular Acidosis
  • Diarrhea
  • Ureteroenteric fistula
  • Pancreaticoduodenal fistula

Of these, RTA is most likely given her history and physical. Which RTA however?

RTA type 1

  • Affects distal tubules
  • Hypokalemia 2/2 H+ secretion

RTA type 2

  • Affects proximal tubules
  • Hypokalemia 2/2 failed hco3 reabsorption from the urine by the proximal tubular cells

RTA type 4

  • Affects adrenal glands
  • Hyperkalemia 2/2 aldosterone deficiency

So this patient has RTA type 4, treat with dextrose for the hypoglycemia, hydrocortisone for glucocorticoid and fludrocortisone for the mineralcorticoid activity.


Thanks to Jake Isserman for his informative morning report.