The Science of COVID-19: Acute kidney injury: Protein or blood in the urine

Dr. Haimchand Barran
MMSc Internal Medicine/Infectious Diseases
Fellowship — Nephrology
Nephrology Department – GPHC

As mentioned in previous articles, some patients with COVID-19 have displayed kidney damage through acute kidney injury (AKI), mild proteinuria (protein in the urine), hematuria (blood in the urine), or slight elevation in creatinine (blood marker testing for kidney function). Today we will cover protein and blood in the urine in our continuing series.

Protein in the urine
People with proteinuria have unusually high amounts of protein in their urine. The condition is often a sign of kidney disease. Your kidneys are filters that don’t usually let a lot of protein pass through. When the kidney is damaged, proteins such as albumin may leak from your blood into your urine. You can also have proteinuria when your body makes too much protein.
Kidney disease often has no early symptoms. Protein in your urine might be one of the first signs. Your doctor may spot proteinuria on a urine test during a routine physical. Over time, as it gets worse, you might have symptoms that include foamy or bubbly urine; swelling (edema) in your hands, feet, belly and face; urinating more often; shortness of breath; fatigue; loss of appetite; upset stomach and vomiting; and muscle cramps at night.
Some common things that can cause proteinuria include dehydration, inflammation, low blood pressure, fever, intense activity, high stress, kidney stones, taking aspirin every day, and very low temperatures.
Conditions that damage your kidneys can also make you have too much protein in your urine. The two most common are diabetes and high blood pressure.
Other serious conditions that can cause proteinuria include immune disorders such as lupus; kidney inflammation (glomerulonephritis); a blood cancer called multiple myeloma; preeclampsia (which affects pregnant women); a buildup of protein in your organs (amyloidosis); cardiovascular disease; intravascular hemolysis; a condition in which red blood cells are destroyed; kidney cancer, and heart failure.
Things that might make you more likely to have protein in your urine include obesity; being over 65 years of age; a family history of kidney disease; and being of African-American, Native-American, Hispanic, or Pacific Islander descent.
Some people get more protein into their urine while standing than while lying down. This condition is called orthostatic proteinuria. A urine test, called a urinalysis, can tell whether you have too much protein in your urine.

Blood in the urine
Having blood in your urine can be a sign that something is wrong with your kidneys or another part of your urinary tract. The medical name for blood in your urine is hematuria.
There are two types of hematuria: if you can see the blood in your urine, it is called gross hematuria; and if you cannot see the blood in your urine without looking at it under a microscope, it is called microscopic hematuria.
Anyone can have hematuria, but you might be more likely to have it if you have a family history of kidney disease; have an enlarged prostate (in men); have a history of getting kidney stones; are taking certain medicines, such as pain relievers, blood thinners or antibiotics; participate in strenuous (difficult) exercises; or currently have, or recently had, an infection.
There are many reasons that might cause you to have blood in your urine. Having blood in your urine does not necessarily mean you have kidney disease. Some common causes are menstruation; strenuous (difficult) exercises; sexual activity; and having a virus, injury or infection such as a urinary tract infection (UTI).
Other more serious problems can cause you to have blood in your urine. Some of these problems include kidney or bladder cancer; irritation or swelling in your kidneys, prostate (in men) or another part of your urinary tract; polycystic kidney disease; blood clots, or diseases that cause problems with blood clotting; and sickle cell disease.
You may not notice any symptoms if you have microscopic hematuria, but if you have gross hematuria, you may notice that your urine is pink, red or brown. This happens because the blood in your urine gives it a different colour. If you have gross hematuria, you may also get blood clots in your urine, which can be painful.
If you notice that your urine has a colour that is different from the normal, or if you are experiencing pain when you urinate, tell your healthcare provider. He or she can do some tests to figure out why you have blood in your urine; or what is causing the pain, and what treatment would be best for you.
The treatment for having blood in your urine depends on what is causing the problem. For example, if you have blood in your urine because of an infection, your doctor might tell you to take an antibiotic medicine. If you have blood in your urine for another reason, you might need a different kind of treatment.
To find out why you have blood in your urine, your doctor might ask you for a urine sample. The urine sample can be used to test for signs of an infection, kidney disease, or other problems. Your doctor will use the results of the urine test to decide if you need more tests, or if you can start a treatment.

Article submitted as part of the Ministry of Health’s COVID-19 public information and education programme. For questions, email [email protected].