The hyponatramia of multiple myeloma is true and not pseudohyponatramia.
The hyponatremia found in multiple myeloma and which is associated with a reduced anion gap (ag) is considered to be pseudohyponatremia due to the displacement of water by the high globulin content in the blood. Serum proteins participate in acid-base balance. Stewart and other authors in their approach to acid-base interpretation acknowledge electrical neutrality as a fundamental characteristic of body fluids. Furthermore, they have shown that both the strong ion difference (SID) and protein, specifically, negatively-charged albumin affect hydrogen ion concentration (H(+)) in the body--i.e., for example an increase in SID leads to a decrease in H(+) and a decrease in albumin leads to a similar effect. The M proteins of multiple myeloma are positively charged. As a result they cause a decrease in sodium levels and the anion gap and thus a true hyponatremia.
Sachs
Jeffrey
J
Department of Anesthesia and Intensive Care, Meir Hospital, University of Tel Aviv, Kfar Saba, Israel. jeffrey.sachs@clalit.org.il <jeffrey.sachs@clalit.org.il>
Fredman
Brian
B
D000136:Acid-Base Equilibrium / Q000502:physiology*; D001798:Blood Proteins / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007010:Hyponatremia / Q000150:complications* / Q000503:physiopathology; D008954:Models, Biological; D009101:Multiple Myeloma / Q000150:complications*; D009994:Osmolar Concentration; D012964:Sodium / Q000097:blood*
D001798:Blood Proteins; D012964:Sodium