Lanthanum therapy is used to treat hyperphosphatemia in end-stage renal disease 1. It is taken as oral tablets (usually in the chemical form Lanthanum carbonate) which dissociate in the acidic environment of the stomach. The released trivalent Lanthanum cation has a high affinity for dietary phosphate. As Lanthanum is poorly absorbed in the gut, the phosphate is excreted rectally 5. Lanthanum is a naturally occurring rare earth element with atomic number 57, one atomic number higher than barium. Lanthanum strongly absorbs x-rays and has contrast-like agent properties 6.
Abdominal pain and constipation are common complications 5. It has been proposed that abdominal radiographs can be used to assess patient compliance 2,8.
Radiography will demonstrate radio-opaque deposits within the entire gastrointestinal tract, particularly the colon 1,2,6. This can be mistaken for retained barium or geophagia. Lanthanum is known to cause beam hardening on CT 7.
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- 7. Hayashi H, Machida M, Sekine T, Yamaguchi H, Kiriyama T, Kumita S. Beam-hardening artifacts on computed tomography images caused by lanthanum carbonate hydrate in a patient on dialysis. (2010) Japanese journal of radiology. 28 (4): 322-4. doi:10.1007/s11604-010-0426-0 - Pubmed
- 8. David S, Kirchhoff T, Haller H, Meier M. Heavy metal--rely on gut feelings: novel diagnostic approach to test drug compliance in patients with lanthanum intake. (2007) Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. 22 (7): 2091-2. doi:10.1093/ndt/gfm208 - Pubmed