Narrative Review: Evolving Concepts in Potassium Homeostasis and Hypokalemia

Abstract

Humans are intermittently exposed to large variations in potassium intake, which range from periods of fasting to ingestion of potassium-rich meals. These fluctuations would abruptly alter plasma potassium concentration if not for rapid mechanisms, primarily in skeletal muscle and the liver, that buffer the changes in plasma potassium concentration by means of transcellular potassium redistribution and feedback control of renal potassium excretion. However, buffers have capacity limits, and even robust feedback control mechanisms require that the perturbation occur before feedback can initiate corrective action. In contrast, feedforward control mechanisms sense the effect of disturbances on the system’s homeostasis. This review highlights recent experimental insights into the participation of feedback and feedforward control mechanisms in potassium homeostasis. New data make clear that feedforward homeostatic responses activate when decreased potassium intake is sensed, even when plasma potassium concentration is still within the normal range and before frank hypokalemia ensues, in addition to the classic feedback activation of renal potassium conservation when plasma potassium concentration decreases. Given the clinical importance of dyskalemias in patients, these novel experimental paradigms invite renewed clinical inquiry into this important area.

Gitelman Syndrome: An Important Cause of Severe Hypokalemia and Periodic Paralysis

“…The last possibility is therefore increased renal loss that should be confirmed by findings of high urinary potassium excretion. In our case, hypokalemia was proven to be in renal origin as we can demonstrate high potassium loss (high urinary potassium excretion, high FE K and high TTKG) [13]. The hypothesis of diuretic abuse could also fit well with renal hypokalemia.…”

“…anorexia nervosa, long-term hunger), potassium shift from extracellular to intracellular fluid compartment, non-renal loss (i.e. sweating, vomiting and diarrhea), and excess renal potassium losses [11,13]. Hypokalemia in our patient seemed not to be related to inadequate intake as anorexia nervosa and long-term hunger were not detected.…”

The mislabelling of deoxycorticosterone: making sense of corticosteroid structure and function

“…As an addendum, it is interesting to note that the actions even of aldosterone on potassium excretion are not necessarily physiological, and though its role may once have been considered crucial, other mechanisms for potassium regulation must now be considered relevant (Rabinowitz 1996, Greenlee et al 2009). …”

Hipopotasemia recurrente y de difícil control en un paciente con leucemia linfoide aguda

“…En el enfoque inicial de estos casos es necesario evaluar si el potasio se está perdiendo por vía gastrointestinal o renal, si la ingesta de potasio es inadecuada, o si el potasio se está redistribuyendo en el organismo (ingreso a las células) (12)(13)(14); una historia clíni-ca completa ayuda a saber si el paciente tiene una adecuada ingesta de potasio o si este ion se está perdiendo por vía gastrointestinal en el caso de diarrea, vómito, fístulas intestinales, etc. (12).…”