A follow‐up on desiderosmia (olfactory craving), a novel symptom associated with iron deficiency anemia
Authors: Bryar R. Hansen, Wayne A. Bottner, Aishwarya Ravindran, Ramona DeJesus, Ronald S. Go
Journal: American Journal of Hematology (2017)

As a sequel to our previous study,1 we would like to further comment on the topic of desiderosmia (olfactory cravings). We previously described three patients with iron deficiency anemia (IDA) presenting with symptoms of olfactory cravings, with compulsion to smell a variety of substances. We have designated the name, "desiderosmia," for this novel symptom. After treatment for IDA, the patients' olfactory craving symptoms resolved. In this article, we reviewed English medical literature and the World Wide Web to determine if such olfactory cravings associated with iron deficiency anemia had been previously reported. We searched the PubMed, Google, and Google Scholar to find publications, reports, presentations, or testimonies of individuals in online blogs using a combination of search terms including "nasal," "olfactory," "smell," "craving," "iron deficiency," and "anemia." Although this specific symptom has only been previously published once in medical literature,1 we did find a large number of online patients self-reporting such a phenomenon potentially corroborating our practice experience. Upon further exploration using Google search engine, we came across a number of online blog posts, mostly in pregnancy blogs, in which participants described this unique symptom.2, 3 These women reported powerful cravings of olfaction, and were frequently overtaken by a strong desire to smell certain odors. The types of substances craved and their associated medical conditions (when reported) are summarized in Supporting Information Table S1. The effects of IDA on the olfactory system have only been minimally explored. It is known that several key enzymes necessary for proper olfaction such as neuronal nitric oxide synthase, tryptophan dioxygenase, and tyrosine hydrolase require either heme or inorganic iron for structure or activity.4, 5 In an animal study, iron-deficient rats were observed to have prolonged exploratory time (sniffing) for attractive odorants compared to controls. The hypothesis was that IDA decreased the activity of these enzymes resulting in a net reduction of inhibitory olfactory inputs.6 Another study compared the olfactory function of IDA patients with healthy subjects and found a heightened sensitivity (lower threshold) in detecting odorant among patients with IDA. These reports support a plausible association between the physiological changes in olfaction and iron store. The mystery behind the pathophysiology of this symptom is a driving factor for further research and exploration. Additionally, it would be interesting to investigate what factors potentially account for the discrepancy between the volume of reports seen in online blogs and those documented in clinical practice. Perhaps these symptoms are being overlooked or not screened for in clinical encounters, and therefore leading to a misunderstanding of this symptom in practice. By placing a name to this symptom, we hope to contribute to a better understanding and recognition of these olfactory cravings by both patients and physicians. All authors declare no conflicts of interests. Additional Supporting Information may be found online in the supporting information tab for this article. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.