Lanthanum Carbonate Opacities-A Systematic Review

Abstract

Background: Lanthanum carbonate is a phosphate binder used in advanced kidney disease. Its radiopaque appearance has been described in many case studies and case series. Misinterpretation of this phenomenon leads to unnecessary diagnostic tests and procedures. The objectives of this study were to summarize the literature on lanthanum carbonate opacities and present a visual overview.

Methods: A systematic search was conducted using MEDLINE, Embase, and Web of Science. We included all types of studies, including case reports/studies, describing radiological findings of lanthanum carbonate opacities in patients with chronic kidney disease. No filter for time was set.

Results: A total of 36 articles were eligible for data extraction, and 33 articles were included in the narrative synthesis. Lanthanum carbonate opacities were most commonly reported in the intestines (26 studies, 73%), stomach (8 studies, 21%), and the aerodigestive tract (2 studies, 6%). The opacities in the intestine were most frequently described as multiple, scattered radiopaque densities, compared with the aerodigestive tract, where the opacities were described as a single, round foreign body. Suspicion of contrast medium or foreign bodies was the most common differential diagnosis. LC opacities in patients with CKD are commonly misinterpreted as foreign bodies or suspect contrast media.

Conclusions: CKD patients treated with LC may have opacities throughout the digestive tract that can vary in appearance. Stopping LC treatment or changing to an alternative phosphate binder prior to planned image studies can avoid diagnostic confusion. If this is not an option, knowledge of the presentation of LC opacities is important.

Keywords: CKD; image studies; lanthanum carbonate.

Figure 1

Flowchart on the included studies and the screening process according to PRISMA.

Figure 2

(a) Visual overview of lanthanum carbonate opacities. Axial CT images of lanthanum carbonate hydrate (Fosrenol chewable tablet) (window level 1500, window width −500) are shown, with a strong artifact due to a beam-hardening effect on the left, and on the right, with a window level of 15,000 and window width of 4000. (b) Beam-hardening artifacts on computed tomography images are also presented, caused by lanthanum carbonate hydrate in a patient on dialysis. Reprinted with permission from ref. [24]. Copyright 2010. Japanese Journal of Radiology.

Figure 3

Plain abdominal radiography in which lanthanum carbonate opacities are observed in the totality of the colonic frame (a). (b) a coronal multiplanar reconstruction computed tomography (CT) image with strong artifacts caused by tablets in the ascending and transverse colon is observed. Lanthanum carbonate has a radiopaque appearance on the plain abdominal radiography. Reprinted with permission from ref. [27]. Copyright 2016 Revista Española Enfermedades.

Figure 4

A comparison of an abdominal ultrasonogram from a patient treated with lanthanum carbonate and that of a healthy man in his 30s is presented. The portion observed as a white line below the transversus abdominis (white arrows) is the wall of the gastrointestinal tract. ∆: External oblique muscle; *: Internal oblique muscle; ☆: Transversus abdominis muscle; Lanthanum carbonate hydrate causes artifacts on ultrasound reprinted with permission from ref [28] under the Creative Commons Attribution 4.0 International License. Copyright Journal of Anesthesia 2015.