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| Indium lung | |
|---|---|
| Specialty | Pulmonology |
Indium lung is a rareoccupational lung disease caused by exposure to respirableindium in the form ofindium tin oxide. It is classified as aninterstitial lung disease (diffuse parenchymal lung disease).[1] The indium industry is primarily based in Japan, where the majority of cases have been reported.
The major signs of indium lung arepulmonary alveolar proteinosis andpulmonary fibrosis. Symptoms includedyspnea (shortness of breath), cough, and increasedsputum production.Hemoptysis has also been seen in people with indium lung.[1] Other symptoms seen in some but not all cases includedigital clubbing, lowDLCO (capacity to move oxygen from thealveoli into the blood), and loweredforced expiratory volume.Emphysema has been associated with indium lung, but may not be part of the syndrome.[2]
Lung cancer may be related to indium lung disease, though indium is not a known carcinogen.[1]
Indium lung is caused by exposure toindium tin oxide in a variety of occupational contexts, including reclamation and production.[1] Exposure to indium tin oxide as it reacts can lead to exposure to indium metal,indium hydroxide, andindium oxide.
The exact mechanism of pathogenesis is unknown, but it is hypothesized that indium may exacerbate existing autoimmune disorders or thatphagocytosis of indium byalveolar macrophages may cause dysfunction in the macrophages.[2]
CT scanning andradiography can be used to aid in the diagnosis of indium lung. CT abnormalities includeground-glass opacities, interlobular septal thickening,honeycombing, andbronchiectasis.[1][2]
Multiple abnormal laboratory findings have been noted in indium lung. High levels of serum indium have been found in all cases of indium lung. Other abnormal laboratory values that have been found include elevatedalanine aminotransferase, elevatedaspartate aminotransferase, elevatedC-reactive protein, elevated interstitial lung disease markers, and elevatedGM-CSFautoantibodies.[2]
TheNational Institute of Occupational Safety and Health, Japan (JNIOSH) set limits for acceptable exposure at 0.0003 mg/m3 after the discovery of indium lung.[2][3] Methods for reducing indium exposure are thought to be the best mode of protection. Medical surveillance of indium workers is also a method of prevention.[2]
There is no standardized treatment for indium lung disease. Treatment options includepulmonary lavage andcorticosteroid therapy.[1][2]
Prognostic factors were a matter of research as of 2012, but preliminary evidence suggests that duration of employment and reported use of respiratory protection are not prognostic factors, but the serum level of indium may be a prognostic factor - higher levels of serum indium have been associated with worse prognoses. Indium lung disease has been fatal in several cases.[2]
It was first described by a group of Japanese researchers in 2003.[1][4]
Cases have been reported inJapan, theUnited States, andChina.[1][2][5] The indium industry is mainly based in Japan, where the bulk of cases have occurred; indium industry is also present in the US, China,Taiwan, andSouth Korea.[4] As of 2010, 10 cases had been described, though more than 100 indium workers had documented respiratory abnormalities.[1]
