My patient with renal insufficiency developed hyponatremia after an IV contrast study.  Is there a connection between hyponatremia and iodinated contrast media?

There are several reports in the literature of hyponatremia (sometimes severe) developing in patients undergoing coronary angiography or routine IV contrast CT studies. 1-3 Although generally asymptomatic, severe hyponatremia with symptoms may also occur, particularly in those at risk of hyponatremia due to other factors.  

In a case series of 5 patients with advanced renal disease who underwent cardiac catheterization and developed post-procedure hyponatremia, the mean plasma sodium concentration decreased from 138.6 mEq/L to 122.6 mEq/L within 2-22 hours post-procedure; no patient had any neurological symptoms associated with hyponatremia. There was a strong correlation between dose of contrast administered and change in sodium level. 2

Severe symptomatic hyponatremia (confusion, stupor) was also reported in an elderly woman with blood creatinine of 0.9 mg/dL following coronary angiography (baseline plasma sodium 142 mmo/L vs. 115 mmol/L >16 hours post-procedure).  The authors suggested that a diagnosis of hyponatremia be considered in any patient who develops behavioral or neurologic manifestations after coronary angiography.3

Aside from coronary angiography, a prospective study among 103 adults (mean serum creatinine 0.79 mg/dl) undergoing contrast-enhanced CT found a drop in serum sodium from a mean concentration of 136 mmol/L to 132 mmol/L 24 hours after the procedure without any associated symptoms.1

Potential mechanisms for the development of hyponatremia after IV contrast studies include hemodilution due to translocation of fluid from intracellular space caused by high osmolality of the contrast media.1  

Bonus Pearl

Did you know that even the newer “low osmolar contrast” agents are more than 3 times the osmolality of blood?4

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  1. Sankaran S, Saharia GK, Naik S, et al. Effect of iodinated contrast media on serum electrolyte concentrations in patients undergoing routine contrast computed tomography scan procedure. Int J Appl Basic Med Res 2019;9:217-220.;year=2019;volume=9;issue=4;spage=217;epage=220;aulast=Sankaran
  2. Sirken G, Raja R, Garces J, et al. Contrast-induced translocational hyponatremia and hyperkalemia in advanced kidney disease. Am J Kidney Dis 2004;43:e9.1-e9.5.
  3. Jung ES, Kang WC, Jang YR, et al. Acute severe symptomatic hyponatremia following coronary angiography. Korean Circ J 2011;41:552-554.
  4. Bucher AM, De Cecco CN, Schoefpf UJ, et al. Is contrast medium osmolality a causal factor for contrast-induced nephropathy? BioMed Res International 2014; Volume 2014, article ID 931413.

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My patient with renal insufficiency developed hyponatremia after an IV contrast study.  Is there a connection between hyponatremia and iodinated contrast media?