Potassium in IVF

Q: The addition of potassium to isotonic saline makes it? ((select one) 

 A) hypertonic 
 B) hypotonic


Answer:  A

The addition of potassium to 0.9 normal saline (NS) should be taken seriously as it can have a significant effect on serum osmolality and consequently on the water balance across the cell. Potassium in 0.9 NS converts it from an isotonic solution to a hypertonic solution. For example, the addition of 40 mEq of potassium to 1 Litre of 0.45 NS converts it to a solution which is osmotically equal to three-quarters of 0.9 NS. Despite increasing the tonicity of the solution, potassium does not help in expanding the same extracellular fluid (ECF) as most of the potassium quickly shifts inside the cell.

This concept is extremely important during the management of Diabetic Ketoacidosis (DKA) where serum is already hyperosmolar and early addition of potassium can worsen the hyperosmolarity. Potassium management is probably the trickiest part in the management of DKA and should be initiated and followed through with extreme care with a guided protocol. This concept again becomes of paramount effect during IVF management in End Stage Renal Disease (ESRD) patients.

#electrolytes
#waterbalance
#endocrinology
#nephrology


References/further readings:

1. Adrogué HJ, Lederer ED, Suki WN, Eknoyan G. Determinants of plasma potassium levels in diabetic ketoacidosis. Medicine (Baltimore) 1986; 65:163. 

2. Beigelman PM. Potassium in severe diabetic ketoacidosis. Am J Med 1973; 54:419. 

3. Murthy K, Harrington JT, Siegel RD. Profound hypokalemia in diabetic ketoacidosis: a therapeutic challenge. Endocr Pract 2005; 11:331.