Seasonal K disturbunce

Case: 34 years old otherwise healthy male received a call from his Primary Care Physician (PCP) office in Houston, Texas, to go to Emergency Room (ER) due to severe potassium level disturbance reported from his well-check labs last week. PCP is out on summer vacation. The repeat potassium level at ER was reported at the lower limit of the reference range. Three more patients presented to ER due to similar phone calls from their PCP offices. Probable cause is? (Select one)

A) Seasonal pseudohyperkalemia

B) Seasonal pseudohypokalemia 

Answer: B

One interesting phenomenon which is less recognized is the occurrence of seasonal hypokalemia in the population during the summer months. This phenomenon is mostly reported from blood samples collected on out-patient during summer months. If the sample is not stored or transported per guidelines results in a reversible in vitro phenomenon mediated by sodium-potassium-exchanging-ATPase due to increased temperature. Still needs to fully explain why many of these patients on repeated labs in a hospital setting have their potassium at the lower limit of the reference range, though the same mechanism, i.e., mediation by sodium-potassium-exchanging-ATPase is suspected.

#electrolytes

#lab-medicine

Reference:

Sodi R, Davison AS, Holmes E, Hine TJ, Roberts NB. The phenomenon of seasonal pseudohypokalemia: effects of ambient temperature, plasma glucose and role for sodium-potassium-exchanging-ATPase. Clin Biochem. 2009 Jun;42(9):813-8. doi: 10.1016/j.clinbiochem.2009.01.024. Epub 2009 Feb 14. PMID: 19232334.