The Sun and Your kidneys
There is no doubt that sunlight does have health benefits. For the past 50 years, it has been well established that the best benefit of the sun is its ability to increase the body’s vitamin D supply; in western nations, one of the most common causes of vitamin D deficiency is a lack of outdoor sun exposure. But too much exposure to the sun is not recommended. The universal warning to people all over the globe is to limit exposure to excess sun. The UV rays of the sun can cause direct damage to the cell’s genetic unit (DNA) and promote several types of skin cancers. In addition, the sun’s rays also damage the collagen fibers, leading to accelerating aging and premature formation of wrinkles. Too much sun exposure is also known to cause cataracts and may cause reactivation of certain viruses.
Who is at risk for photosensitivity
However, the most common effect of UV rays exposure is photosensitivity, which can present like sunburn. Healthcare workers usually recommend people with the following conditions to avoid the sun:
- People on certain medications (eg antibiotics, antihistamines, cancer drugs, diabetic medications, etc)
- Individuals with a transplant and are on certain immunosuppressive medications
- Certain genetic disorders like xeroderma pigmentosa
- Individuals on dialysis need to protect their catheter from sun exposure
- Individuals with certain autoimmune disorders
Sunlight and autoimmune disorders
Over the years many reports have appeared indicating that individuals with the UV rays of the sun may be playing a role in the development of some autoimmune disorders, especially in women. A recent study by scientists at the National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health reported that women who resided in areas of high UV ray exposure who had myositis (inflammation of the muscle) were more likely to develop the autoimmune disorder dermatomyositis, which presents with a distinctive rash and severe weakening of the muscles. In addition, there are many reports indicating the sunlight cannot only cause severe photosensitivity reactions in individuals with lupus, but also affect other organs in the body.
Lupus
Lupus is an autoimmune disorder that can cause inflammation of the skin, joints, kidneys, blood cells, heart, brain, and lungs, In lupus the individual develops an immune attack against its own tissues. As many as 75% of individuals with lupus are photosensitive, meaning they develop a sunburn like reaction when exposed to the UV rays. These individuals are frequently told to avoid sun exposure to prevent lupus flare-ups. Studies published in the past have shown that in close to 4/5th of individuals with lupus, sunlight exposure can trigger both local inflammation of the skin and flare up of kidney disease. But how the rays of the sun affect the kidney in lupus was not well understood until recently.
The Sun and the kidney
Well now a new study provides insight into how Ultraviolet light can worsen the symptoms in individuals with lupus. The study was conducted at the Geisel School of Medicine at Dartmouth and the University of Washington.
In this study the researchers looked at a specific white blood cell (neutrophil) which is the first responder to any kind of inflammation in the body. In their study, the researchers exposed mice to UV light. They then followed markers of inflammation and injury to the skin and other organs including the kidney. What they observed was the following UV light exposure to the skin, these inflammatory cells also migrated to the kidney and caused transient loss of function. What was interesting was that even a single exposure of UV light to the skin stimulated the neutrophils to migrate to the kidneys and cause injury. After a few days, the mice were able to recover their kidney function. The researchers believe that the same pathological mechanism may be occurring in lupus individuals leading to loss of protein in the urine.
Prevention
While many more studies are required to develop a better understanding of how sunlight can cause organ damage, healthcare workers do recommend the following precautions in individuals with lupus:
- Always wear a sunscreen before going outdoors
- Avoid sun exposure from 10 am to 3 pm when it is the most intense
- Wear protective garments to protect the skin and eyes
- Wear sunglasses that filter the UV rays
- Consider wearing a wide brimmed hat and long sleeved shirts
- If you’re on peritoneal dialysis, protect your catheter at all times.
- Follow up with your healthcare provider on a regular basis
For more info on how your environment may be affecting your kidney health, be sure to tune in to the official Healthy Kidney Inc. YouTube channel for the latest on all things kidney-related!
References
- New insights into link between sunlight exposure and kidney damage. https://www.aninews.in/news/health/new-insights-into-link-between-sunlight-exposure-and-kidney-damage20210122085031/
- Sun-Damaged Skin
https://www.health.harvard.edu/staying-healthy/sun-damaged-skin-a-to-z
- GETTING OUTSIDE THIS SUMMER WITH AUTOIMMUNE DISEASES https://www.benaroyaresearch.org/blog/post/getting-outside-summer-autoimmune-diseases
- Sun Exposure May Trigger Certain Autoimmune Diseases in Women
