Renal health and COVID-19

Kidney disease – also termed the “silent killer” as many sufferers do not realise they have it until it is very advanced – affects an estimated 10% of the global population. In sub-Saharan Africa, where the incidence of conditions such as hypertension, HIV and diabetes is actively rising, researchers believe that chronic kidney disease (CKD) is set to become a major health risk. ^[1]

In the context of COVID-19, the growing incidence of renal conditions is a concern. Patients who have kidney disease are at increased risk of developing severe COVID-19, thus increasing the risk of death. In turn, COVID-19 is found to cause acute kidney injury (AKI) in COVID patients. ^[2]

Ahead of World Kidney Health Day (10 March)^[3], it is important to examine the relationship between kidney health and COVID-19.

The reason why kidneys are so susceptible to COVID infection

Scientists have found that to enter the body, the COVID-19 virus attaches to the angiotensin converting enzyme 2 (ACE-2) receptors. These are in the membranes of cells lining the kidneys and other organs. But according to researchers, there is a higher relative proportion of these receptors in the proximal tubule (i.e. the kidney portion that is responsible for absorbing water and nutrients from the blood). This may explain why the kidneys are especially susceptible to damage from a COVID-19 infection. In addition, the body’s immune system creates an inflammatory response, in an effort to combat the virus, and this can cause inadvertent damage to kidney cells, too.  ^[4]

Individuals with existing kidney disease (especially those who are receiving dialysis or have recently received a kidney transplant and are prescribed immunosuppressants) are at an even higher risk of more severe COVID-19 infection and related health complications.^[5]

Researchers are developing treatment protocols requiring COVID patients to receive kidney testing via urine tests upon admission to hospital, to improve the likelihood of identifying potential AKI early (and thus, also preventing serious disease complications such as organ failure or even death). ^[6]

In addition, it is recommended by specialists that patients over the age of 60, as well as those who suffer from any pre-existing kidney conditions, heart illness, obesity or diabetes should be carefully monitored for signs of kidney damage, to monitor the possible development of AKI and enable swift treatment.

Early detection: 7 symptoms of kidney disease

The following physical symptoms may point to impaired kidney function (and kidney disease):

1. Edema (swelling) of ankles, feet or legs, or periorbital area (around the eyes). This is the result of the accumulation of fluid – a sign of kidney failure^[7]
2. Weakness and fatigue ^[8]
3. Foamy or bloody urine
4. Sharp pain in the lower back or abdomen
5. Elevated blood pressure
6. Anaemia and declining haemoglobin levels
7. Decreased appetite and changes in taste (many patients report metallic taste)

Vitamins and nutrients boost immunity

Researchers have established that nutrient and vitamin supplementation can boost immunity against viral infections (such as COVID-19). In fact, one study has shown that the following nutrients, elements and vitamins have a positive effect on immunity and renal health: ^[9]

• Vitamin A: Enhances immune function.
• Vitamin C: An antioxidant that fights infections by supporting immune cell function; in addition, it improves iron absorption in the body. However, it has been noted that “oxalosis which is the accumulation of the metabolic by-product of ascorbic acid must be inhibited in CKD [chronic kidney disease] patients, therefore intakes greater than 100–200 mg/day should be avoided”.
• Vitamin D: Promotes healthy immune response. Studies have shown that a deficiency in Vitamin D is associated with heightened susceptibility to respiratory viruses.
• Vitamin E: An antioxidant that protects cells and promotes immunity. Some studies suggest it has a positive effect on dialysis patients.
• Quercetin: A flavonoid derived from plant foods. Some studies on COVID patients in New York and China demonstrated that quercetin improved renal function and lowered renal inflammation.
• Zinc: This essential trace element improves the function of immune cells.
• Selenium: A trace element that reduces inflammation and promotes healthy immune response.
• Magnesium: A deficiency of magnesium “might not only lead to weakness of immune response against viral infection such as COVID-19, but also could adversely affect the risk of AKI”.
• Melatonin: This anti-inflammatory and anti-oxidant element has been found to protect against lung injury during viral infection, and appears to prevent kidney damage too. 

Tips for maintaining kidney health

• Eat a healthy diet, rich in fresh fruit and vegetables, lean protein, fibre.
• Supplement with probiotics, to support healthy digestion and immune function. ⁶
• Drink plenty of fresh water daily to help the kidneys perform their function.
• Maintain a low salt/sodium diet.
• Maintain a healthy weight and an active lifestyle. ³
• Check blood sugar, blood pressure and kidney function regularly (especially after the age of 60).
• Quit smoking.

With this knowledge, HCPs are well-equipped to assist their patients in maintaining good renal health, even if recovering from COVID-19.