It is crazy to think back to a few months ago and see how much has changed. In March, SARS-CoV-2, which you probably know as COVID-19, was declared a global pandemic. As of June 10, there are over 7 million diagnosed cases worldwide, with 404,000 fatalities and new information about the virus being discovered every day. One such finding links severe cases of COVID-19 to kidney damage. More specifically, a French study found that up to 80% of critically ill patients with COVID-19 end up with Fanconi syndrome or acute kidney injury (AKI). As a result of these findings, patients hospitalized for COVID-19 should later be monitored for kidney disease or kidney damage. Find the full study results in the Clinical Kidney Journal.
Fanconi Syndrome
Fanconi syndrome is a kidney disorder that specifically affects the proximal tubules. It should not be confused with Fanconi anemia, an unrelated blood disorder. Normally, the proximal tubules help reabsorb certain substances back into the bloodstream. But for those with Fanconi syndrome, these substances (like glucose, uric acid, and potassium) are instead removed from the body through urine.
Fanconi syndrome can be caused by genetic mutations, medications, heavy metal exposure, other conditions (like Wilson disease), and kidney damage. In fact, it often occurs in tandem with another disorder. Symptoms include:
- Excessive thirst and excessive urination
- Dehydration
- Bone weakness and pain
- Blood acidification
- Bone fractures
- Muscle weakness and poor muscle tone
- Rickets
- Nausea and vomiting
Learn more about Fanconi syndrome.
Acute Kidney Injury
Acute kidney injury (AKI), or acute renal failure, occurs when your kidneys suddenly stop working within a few hours or a few days. It results from kidney damage, which can include:
- Blockages like kidney stones, blood clots, tumors, or an enlarged prostate
- Infections
- Medications
- Drug or alcohol abuse
- Kidney or blood diseases
- Serious burns
- Dehydration
- Allergic reactions
During acute kidney injury, waste (that would normally be excreted) builds up in your body. Then, your kidneys experience difficulty with filtration. Acute kidney injury most often affects people who are already sick and hospitalized. Symptoms include:
- Passing less urine than normal
- Confusion
- Extreme fatigue
- Chest pain and shortness of breath
- Nausea and vomiting
- Swelling around the eyes
- Leg, ankle, and foot inflammation
- Seizures and coma (in severe scenarios)
Although acute kidney injury can be fatal if left untreated, early detection and treatment can reverse symptoms and prevent further damage. Learn more about acute kidney injury from the American Kidney Fund.
The Study
Proximal tubule cells have a cell surface receptor that allows the virus to easily infect the body. As a result, the renal system is uniquely at risk during COVID-19 infection. When damage occurs, patients can develop Fanconi syndrome.
A French study sought to understand how monitoring certain symptoms or markers in hospitalized patients could detect proximal tubule damage. Some aspects of their study include:
- 42 patients hospitalized for severe COVID-19 infection. Of these patients, none had prior kidney disease.
- 19.7 days = the mean follow-up.
- 32 patients (75%) developed Fanconi syndrome with at least two tubular abnormalities or damaged areas.
- 8 patients (19%) developed acute kidney injury.
- Of these, 7 patients (88%) developed Fanconi syndrome before acute kidney injury.
- 5 patients (63%) needed dialysis to support kidney function. Of these, 2 patients (40%) remained on dialysis by the end of the follow-up period. 1 patient (20%) was able to stop dialysis after 1 week. 2 patients (40%) died.
- Symptoms that signified kidney damage included:
- Proteinuria – excess protein in the urine. 35 patients (88%) experienced this symptom.
- Phosphate loss in urine – 22 patients (55%) experienced this symptom.
- Increased uric acid in urine – 17 patients (43%) experienced this symptom.
- Glycosuria – excess glucose in the urine. 12 patients (30%) experienced this symptom.
- Ultimately, 7 patients (17%) died; 24 patients (57%) were discharged; and 11 patients (26%) joined in-patient treatment for about one month.
So what do these numbers mean?
The study results show that kidney damage is common in COVID-19 because of the ease of infection. As a result, many patients with severe cases of COVID-19 are at risk of developing Fanconi syndrome or acute kidney injury; this will require continued treatment.
The results also imply that four markers, or symptoms, can highlight kidney damage. By identifying and detecting these, doctors are able to start treatment early. Says Dr. Raphaël Kormann, these markers are:
increased urinary excretion of protein, phosphate, uric acid, and glucose.
Read the source article here.
