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Selenium


Selenium

Article Author:
Trevor Nessel
Article Editor:
Vikas Gupta
Updated:
10/5/2020 10:05:00 AM
For CME on this topic:
Selenium CME
PubMed Link:
Selenium

Indications

Selenium is a trace mineral that exists in minimal concentrations in the body but can play an important role in human health. Food sources high in selenium include Brazil nuts, seeds, mushrooms, fish, seafood, beef, and poultry. [1] Selenium presents in an organic form as selenomethionine in plant food, and in an inorganic form as selenate and selenite in supplements; Both the organic and inorganic forms have greater than 90% bioavailability.[2] Selenium absorption occurs mainly within the duodenum of the small intestine, via an active transport sodium pump.[3]

Selenium provides several functions in the human body. It plays a role in enzymatic functions to catalyze thyroid hormone production.[4] Immune system function relies on selenium, as research has associated the mineral with defending the body against infections, particularly viral in origin.[5] Also, selenium in the form of selenoproteins serves as an antioxidant to protect against reactive oxygen species and reactive nitrogen species.[6]

Selenium plays an essential role in treating dermatologic conditions. Selenium sulfide administration typically is as a topical lotion, foam, or shampoo. The main dermatologic indications include tinea versicolor, seborrheic dermatitis of the scalp, dandruff, and hyperkeratosis.[7][8][9][10] Intact skin does not absorb any of the topical selenium. 

Selenium supplementation is indicated to replete stores in cases of selenium deficiency. However, this is usually secondary to the localized diet, versus an individual problem with the patient. Therefore, a common way to reduce selenium deficiency is via biofortification at the agricultural level.[1] On an individualized level, a therapeutic option is to add selenium-enriched foods into the diet.[1]

Selenium deficiency is rarely associated with Keshan disease, a cardiomyopathy that ranges from heart failure, cardiomegaly, and electrocardiogram abnormalities to cardiogenic shock and demise. The most common demographic includes children and women of child-bearing age in endemic areas of China.[1] In these regions, preventative selenium supplements are essential to reduce the incidence of the disease.

Selenium deficiency occurs more commonly in patients with malabsorption syndrome, particularly caused by stomach and small intestine surgical resections.[11] Removal of gastrointestinal contents reduces the ability for selenium to be absorbed through the small intestine brush border and therefore lowers the selenium serum concentrations below adequate levels. 

Mechanism of Action

Selenium displays several different mechanisms of action. Many of the various effects of selenium involve the incorporation of selenium into different proteins to create selenoproteins.[6] There at least 25 selenoproteins within human tissues that provide different functions in the body.[12]

Selenium serves as a cofactor for glutathione peroxidase, and thus, helps minimize the oxidative damage through cellular metabolism.[6] Selenium, in combination with vitamin E, protects cell membranes and organelles from peroxidative destruction.[1] Thus, selenium can boost host defense and, ultimately, the immune system.

Selenium's necessity in the endocrine system is defined by its role in making active thyroid hormone. The mineral interacts with iodothyronine deiodinase, an enzyme that transforms inactive thyroid hormone (T4) into active thyroid hormone (T3).[1]

As a dermatologic treatment, selenium in the form of selenium sulfide plays an alternative role with several suggestive mechanisms. In the treatment of seborrheic dermatitis, dandruff, and tinea versicolor, selenium sulfide acts as an anti-pityrosporum agent that inhibits the growth of the fungus.[13] Selenium sulfide's cytostatic effect on the epidermis lowers the mitotic rate and cell turnover in the basal layer, consequently reducing the production rate of the stratum corneum and limiting keratotic development.[10] Selenium sulfide blocks enzymes involved in the growth of epithelial tissue.[10] Lastly, research shows that selenium sulfide increases the rate of sebum excretion.[14]

Administration

The most efficient way to obtain selenium is through a well-balanced diet. If additional supplementation is needed, selenium administration can be through both oral and parenteral routes, and the preferred route depends on the indication for use. Most cases of selenium deficiency will reverse with oral supplements or selenium-containing foods. Dermatologic conditions require the use of topical administration of selenium sulfide. Intravenous infusions of selenium are available; however, they must be diluted before injection to prevent tissue irritation.[12]

Adverse Effects

Selenium supplementation has a very low adverse effect profile. A majority of the adverse reactions center around selenium sulfide. The more common adverse effects include redness, burning, itching, stinging, scalp sores, increased oiliness, nail hyperpigmentation, and irritation of the skin, creating a contact dermatitis.[15]  Less common effects associated specifically with the selenium sulfide shampoo include scalp hyperpigmentation, scalp discoloration, and alopecia. A rare non-dermatologic effect includes nausea due to the odor of the medication.[15][16][17][18][19][20]

Contraindications

The only true contraindication to selenium is a previous hypersensitivity reaction with topical application. There are precautions to take when administering selenium in patients with particular comorbidities. Caution is necessary for patients with gastrointestinal dysfunction, as there is evidence of selenium causing gastrointestinal symptoms in these specific patients, such as diarrhea and vomiting.[21] Physicians should be cautious when prescribing dietary supplements to patients with renal failure due to inadequate renal excretion. However, such evidence for precaution with early chronic kidney disease is not as strong compared to patients on dialysis.[22]

Monitoring

Symptoms of selenium deficiency are rare but include [1]:

  • Deformity of bones, cartilage, and joints
  • Restricted movements
  • Myalgias
  • Extremity edema
  • Shortness of breath

Can monitor selenium levels via [1]:

  • Serum selenium levels
  • Scalp hair selenium levels
  • Nail selenium levels
  • Glutathione peroxidase activity in plasma
  • Glutathione peroxidase activity in erythrocytes
  • Glutathione peroxidase activity in thrombocytes
  • Glutathione peroxidase activity in whole blood
  • The concentration of selenoprotein P (SePP)

Toxicity

Selenium is considered a relatively non-toxic supplement. However, extremely high selenium intake can result in diarrhea, fatigue, hair loss, joint pain, nail discoloration or brittleness, and nausea.[21]

Due to selenium supplementation toxicity being extremely rare, there is no current treatment for selenium overdose. If selenium toxicity is suspected, it is best to stop using the supplement. 

Enhancing Healthcare Team Outcomes

Managing selenium deficiency can be a difficult task considering this phenomenon typically occurs in underdeveloped and developing regions of the world where healthcare is limited. Selenium levels are rarely tested for, and physicians and healthcare providers are often unaware of deficiencies and treatment options. Therefore, the entire healthcare team needs to work together, starting with gathering a sufficient history from the patient. Along with physicians, nurses, medical assistants, and technicians can assist with asking questions and collecting data from the patient. Specifically, it is essential to ask about diet, as many selenium-deficient patients lack selenium in the food they consume. Pharmacists must stay up to date with the most recent guidelines regarding selenium supplementation dosing so that pharmacists and physicians can communicate to ensure the most beneficial course of action for patients. 


References

[1] Shreenath AP,Dooley J, Selenium Deficiency 2020 Jan;     [PubMed PMID: 29489289]
[2] Reich HJ,Hondal RJ, Why Nature Chose Selenium. ACS chemical biology. 2016 Apr 15     [PubMed PMID: 26949981]
[3] Vendeland SC,Deagen JT,Butler JA,Whanger PD, Uptake of selenite, selenomethionine and selenate by brush border membrane vesicles isolated from rat small intestine. Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine. 1994 Oct     [PubMed PMID: 7812115]
[4] Wojciechowska-Durczynska K,Lewinski A, Search for relevant indications for selenium supplementation in thyroid diseases. Neuro endocrinology letters. 2017 Aug     [PubMed PMID: 28871707]
[5] Rayman MP, The importance of selenium to human health. Lancet (London, England). 2000 Jul 15     [PubMed PMID: 10963212]
[6] Tinggi U, Selenium: its role as antioxidant in human health. Environmental health and preventive medicine. 2008 Mar     [PubMed PMID: 19568888]
[7] Sánchez JL,Torres VM, Selenium sulfide in tinea versicolor: blood and urine levels. Journal of the American Academy of Dermatology. 1984 Aug     [PubMed PMID: 6480923]
[8] Naldi L,Diphoorn J, Seborrhoeic dermatitis of the scalp. BMJ clinical evidence. 2015 May 27     [PubMed PMID: 26016669]
[9] Danby FW,Maddin WS,Margesson LJ,Rosenthal D, A randomized, double-blind, placebo-controlled trial of ketoconazole 2% shampoo versus selenium sulfide 2.5% shampoo in the treatment of moderate to severe dandruff. Journal of the American Academy of Dermatology. 1993 Dec     [PubMed PMID: 8245236]
[10] Cohen PR,Anderson CA, Topical Selenium Sulfide for the Treatment of Hyperkeratosis. Dermatology and therapy. 2018 Dec     [PubMed PMID: 30203232]
[11] Shakhovskaia AK,Gmoshinskiĭ IV,Shirina LI,Mazo VK, [Selenium sufficiency in patients with malabsorption syndrome and its optimization with selenium enriched food supplements]. Voprosy pitaniia. 2003     [PubMed PMID: 14870587]
[12] Shenkin A, Selenium in intravenous nutrition. Gastroenterology. 2009 Nov     [PubMed PMID: 19874951]
[13] Van Cutsem J,Van Gerven F,Fransen J,Schrooten P,Janssen PA, The in vitro antifungal activity of ketoconazole, zinc pyrithione, and selenium sulfide against Pityrosporum and their efficacy as a shampoo in the treatment of experimental pityrosporosis in guinea pigs. Journal of the American Academy of Dermatology. 1990 Jun     [PubMed PMID: 2142498]
[14] Goldschmidt H,Kligman AM, Increased sebum secretion following selenium sulfide shampoos. Acta dermato-venereologica. 1968     [PubMed PMID: 4177572]
[15] Sánchez JL,Torres VM, Double-blind efficacy study of selenium sulfide in tinea versicolor. Journal of the American Academy of Dermatology. 1984 Aug;     [PubMed PMID: 6384285]
[16] Ranganathan S,Mukhopadhyay T, Dandruff: the most commercially exploited skin disease. Indian journal of dermatology. 2010 Apr-Jun;     [PubMed PMID: 20606879]
[17] Gillum RF, Hyperpigmentation associated with selenium sulfide lotion. Journal of the National Medical Association. 1996 Sep;     [PubMed PMID: 8855644]
[18] Gilbertson K,Jarrett R,Bayliss SJ,Berk DR, Scalp discoloration from selenium sulfide shampoo: a case series and review of the literature. Pediatric dermatology. 2012 Jan-Feb;     [PubMed PMID: 21453309]
[19] Wolf R,Perluk C,Krakowski A, Nail pigmentation resulting from selenium sulfide and copper. International journal of dermatology. 1989 Oct;     [PubMed PMID: 2583901]
[20] GROVER RW, Diffuse hair loss associated with selenium (selsun) sulfide shampoo. Journal of the American Medical Association. 1956 Apr 21;     [PubMed PMID: 13306564]
[21] MacFarquhar JK,Broussard DL,Melstrom P,Hutchinson R,Wolkin A,Martin C,Burk RF,Dunn JR,Green AL,Hammond R,Schaffner W,Jones TF, Acute selenium toxicity associated with a dietary supplement. Archives of internal medicine. 2010 Feb 8;     [PubMed PMID: 20142570]
[22] Jakimowicz-Tylicka M,Chmielewski M,Kuźmiuk-Glembin I,Skonieczny P,Dijakiewicz G,Zdrojewska G,Rutkowski B,Tylicki L,Dębska Ślizień A, Dietary supplement use among patients with chronic kidney disease. Acta biochimica Polonica. 2018;     [PubMed PMID: 29850657]