Makindo Medical Notes

📖 About

• 🧪 Selenium deficiency is rare globally, even in regions with relatively low dietary intake.
• Selenium is an essential trace element, incorporated into selenoproteins (e.g. glutathione peroxidase) that protect against oxidative stress.
• Deficiency manifests only in areas with exceptionally low intake or in special clinical settings (e.g. long-term TPN).

🌍 Aetiology – Selenium Intake Around the World

• New Zealand & 🇫🇮 Finland: 30–50 mcg/day (low intake).
• USA / 🇨🇦 Canada: 100–250 mcg/day (adequate intake).
• Some areas of China: 10–15 mcg/day (very low intake, deficiency diseases described).

🩺 Clinical Features

• Keshan disease: Reversible dilated cardiomyopathy affecting children and young women; prevented (not cured) by sodium selenite 50 mcg/day PO.
• Siberian Russia & 🇨🇳 China: Kashin-Beck disease – chronic osteoarthropathy in children, linked to selenium deficiency and other cofactors (e.g. mycotoxins).
• 💉 Long-term TPN without supplementation: muscle pain, tenderness, proximal weakness, which improves with selenium replacement.
• 🧑‍⚕️ Possible role in impaired immunity and thyroid hormone metabolism (selenium required for deiodinases).

🔍 Investigations

• Plasma selenium levels or glutathione peroxidase activity in RBCs can be measured.
• ⚠️ These are not standard routine tests and often only done in research or specialist centres.

💊 Management

• Selenium replacement (oral or IV, depending on context).
• Typical supplementation: 50–200 mcg/day.
• ⚠️ Avoid excessive intake: high doses may cause selenosis (symptoms include brittle hair/nails, garlic breath odour, neurological issues).
• Prevention: ensure supplementation in long-term TPN and in endemic low-intake regions.

📚 References

• Rayman MP. The importance of selenium to human health. Lancet. 2000.
• WHO/FAO Trace Elements in Human Nutrition and Health.
• NIH Office of Dietary Supplements – Selenium