It is the organic compound with high nitrogen content that is formed in the body during the breakdown of proteins and ammonia.
It is quite harmless, but large amounts can be dangerous, and urea is constantly passed through the kidneys in the urine.
Proteins are broken down into simpler substances known as amino acids, which are then further metabolized in a process known as deamination.
This provides energy for the body or amino acids can be converted to carbohydrates or fats as required by the body.
Most of the deamination occurs in the liver with small amounts being processed in other tissues such as the kidneys.
During the process, various compounds are formed as by-products. Urea is one of these products along with ammonia.
Urea does not affect the pH of body fluids and is quite harmless at low to moderate levels. On the other hand, ammonia can alter the pH of the blood and alter homeostasis.
In addition to being a byproduct of protein breakdown, bacteria in the gut can also produce ammonia which is then absorbed into the bloodstream. The body converts any ammonia to urea.
Excess urea in the blood
Urea is not the only nitrogen waste product in the blood.
Various waste products become highly toxic to the body if they persist in the bloodstream for longer than it should or accumulate at higher than normal levels.
Although a large number of toxins are responsible for the clinical syndrome, urea and creatinine, a compound associated with muscle breakdown, are primarily involved.
There are two terms associated with high levels of urea in the blood.
The first is azotemia, which means a high level of nitrogenous waste in the blood: blood urea nitrogen and creatinine.
The second term is uremia , which refers to clinical signs and symptoms, as well as other biochemical abnormalities seen with elevated urea levels.
Azotemia is prerenal or postrenal. In prerenal azotemia, there is a disorder with blood flow to the kidney, so nitrogenous waste products cannot be filtered.
With postrenal azotemia, the blockage of the urinary tract beyond the kidney that prevents the excretion of urea and other wastes.
What is high uremia?
High uremia is a buildup of urea and other nitrogenous waste products in the blood that are usually excreted by the kidneys into the urine.
With high uremia, the clinical signs and symptoms of this underlying problem become apparent due to the impact of nitrogenous waste products on other systems and the disruption of other metabolic processes .
Depending on the severity of the waste build-up, the condition can range from being asymptomatic to even leading to death.
Causes of high uremia
High uremia is seen primarily with chronic kidney disease, particularly end-stage renal disease (ESRD).
The kidney’s inability to efficiently filter the blood of toxic products allows it to accumulate in the bloodstream. This can be seen with a variety of kidney and systemic diseases, including:
- Urinary stones.
- Polycystic kidney disease.
- IgA nephropathy.
- Hypertension .
- Diabetes mellitus – diabetic nephropathy.
- Systemic lupus erythematosus (SLE).
- Goodpasture syndrome.
Signs and symptoms
High uremia syndrome is not only associated with nitrogenous waste products like urea.
By affecting multiple symptoms and metabolic processes, other compounds, electrolytes, and even hormones disrupt homeostasis.
Some of the signs and symptoms seen with high uremia are not related to nitrogenous waste products, but arise from the primary disorder, often kidney failure.
These signs and symptoms are not specific to uremia, but rather to chronic kidney disease:
- Nausea and vomiting
- Fluid retention (edema)
- Pale yellow sickly skin appearances.
- Itchy skin (pruritus) and rashes (dermatitis).
- Labored breathing
- Pulmonary edema (fluid in the lungs).
- High blood pressure.
- Inflammation of the intestine, particularly the upper and lower portions – esophagitis , gastritis and colitis .
- Metabolic acidosis.
- Congestive heart failure
- Cardiomyopathy (enlarged heart).
- Bleeding disorders.
- High levels of potassium (hyperkalemia).
- High levels of phosphate (hyperphosphatemia).
- Low calcium levels ( hypocalcemia ).
- Peripheral neuropathy.
- Myopathy .
By the time you have developed uremia, your kidneys will be extremely damaged. Dialysis is the main treatment option for uremia.
Dialysis is when the removal of waste, extra fluids, and toxins from your bloodstream is handled artificially rather than by your kidneys. There are two types of dialysis:
A machine is used to remove waste from your blood.
A catheter (small tube) is inserted into the abdomen. A dialysis fluid fills your abdomen. This fluid absorbs waste and excess fluid.
Eventually, the fluid will flush waste from your body when it drains.
A kidney transplant is another treatment option if you develop end-stage kidney failure. A kidney transplant is when a healthy kidney is removed from a living or deceased donor and placed into your body.
You will be prescribed a long-term anti-rejection medication to prevent your body from rejecting the donor kidney.
Researchers are currently working on what is called “regenerative medicine.” This type of treatment can help people with kidney disease and uremia later in life.
It uses cells that can help the body heal its own organs. It is possible that one day it could also slow the progression of kidney disease.