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acid-base disorder

Systematic approach: 1) What is the primary disturbance? 2) Is the compensation appropriate? 3) What is the anion gap? 4) Is the change in anion gap equal to the change in [HCO3-]? Classification: 1) acidosis: pH < 7.37 a) metabolic acidosis: [HCO3-] < 22 meq/L b) respiratory acidosis: PaCOs > 44 mm Hg 2) alkalosis: pH > 7.44 a) metabolic alkalosis: [HCO3-] > 26 meq/L b) respiratory alkalosis: PaCO2 < 36 mm Hg Interpretation: Anion gap (serum): 1) when the primary disturbance is a metabolic acidosis, the anion gap indicates the presence of unmeasured anions 2) when the primary disturbance is other than metabolic acidosis, an increased anion gap reveals a hidden metabolic acidosis 3) a narrow anion gap suggests unexpected cations (i.e. immunoglobulins in multiple myeloma) urine osmolal gap: - provides estimate of urinary ammonium excretion - urine ammonium is ~ 1/2 of the urine osmolal gap - patients with kidney defect have urine ammonium < 30 meq/L - patients with extrarenal losses of bicarbonate have urine ammonium > 80 meq/L

Related

acid-base balance

Specific

metabolic acidosis metabolic alkalosis mixed acid-base disorder respiratory acidosis; hypercapnic acidosis respiratory alkalosis

General

metabolic disease

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 14, 16, 18. American College of Physicians, Philadelphia 2006, 2012, 2018. - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  2. Gennari FJ, Weise WJ. Acid-base disturbances in gastrointestinal disease. Clin J Am Soc Nephrol. 2008 Nov;3(6):1861-8 PMID: 18922984
  3. Adrogue HJ, Madias NE. Secondary responses to altered acid-base status: the rules of engagement. J Am Soc Nephrol. 2010 Jun;21(6):920-3. PMID: 20431042
  4. Berend K et al Physiological Approach to Assessment of Acid-Base Disturbances. N Engl J Med 2014; 371:1434-1445. October 9, 2014 PMID: 25295502 http://www.nejm.org/doi/full/10.1056/NEJMra1003327
  5. Seifter JL. Integration of acid-base and electrolyte disorders. N Engl J Med. 2014 Nov 6;371(19):1821-31. PMID: 25372090
  6. Palmer BF, Clegg DJ Electrolyte and Acid-Base Disturbances in Patients with Diabetes Mellitus. N Engl J Med 2015; 373:548-559. August 6, 2015 PMID: 26244308 http://www.nejm.org/doi/full/10.1056/NEJMra1503102
  7. Madias NE. Renal acidification responses to respiratory acid-base disorders. J Nephrol. 2010 Nov-Dec;23 Suppl 16:S85-91. Review. PMID: 21170892
  8. Raimondi GA et al Acid-base patterns in acute severe asthma. J Asthma. 2013 Dec;50(10):1062-8. PMID: 23947392
  9. Seifter JL, Chang HY. Disorders of Acid-Base Balance: New Perspectives. Kidney Dis (Basel). 2017 Jan;2(4):170-186. Review. PMID: 28232934 Free PMC Article