Anuria: Symptoms, Causes & Treatment

Anuria is the absence of urine production, typically defined as producing less than 50 mL of urine per day, and may be accompanied by swelling in the legs and feet, nausea, and vomiting.

Anuria is most commonly caused by disorders affecting the urinary system, such as urinary tract obstruction or acute kidney injury. It may also occur as a complication of poorly controlled diabetes or hypertension.

Anuria is a medical emergency and should be evaluated immediately in an emergency department. Treatment may involve correcting a urinary tract obstruction, placing a stent, or hemodialysis, depending on the underlying cause, with care guided by specialists such as nephrologists or urologists.

Main symptoms

The main symptoms of anuria are:

• Urinating less than 50 mL per day, in adults

• Blood in the urine, when urine can be passed

• Complete absence of urine production and urination

• Swelling in the legs and feet

• Abdominal pain or lower back pain

• Nausea and vomiting

Dizziness, weakness, fainting, or a general feeling of being unwell may also occur.

Symptoms of anuria can vary depending on the cause. It is important to go to the hospital immediately, as this is a medical emergency that requires prompt treatment.

Confirming a diagnosis

Anuria is diagnosed in the hospital by a healthcare provider through evaluation of symptoms, medical history, and a physical exam. Specialists such as a nephrologist or urologist may be involved depending on the underlying cause.

To confirm the cause of anuria, the doctor may also order blood tests, urine tests, a CT scan, MRI, or renal scintigraphy.

These tests are important for evaluating the structure and function of the kidneys and identifying kidney failure or obstructions, for example.

Main causes

The main causes of anuria are:

1. Acute kidney injury

The cause most commonly associated with anuria is acute kidney failure, now more commonly called acute kidney injury. This occurs when the kidneys are unable to filter the blood and remove toxins from the body.

As a result, harmful substances can build up in the body and lead to symptoms such as lower back pain, fatigue, shortness of breath, and high blood pressure.

What to do: Treatment for acute kidney injury should be guided by a nephrologist in the hospital. It usually involves diuretic medications, IV fluids, limiting salt intake, and, in some cases, hemodialysis.

2. Urinary tract obstruction

Urinary tract obstruction can occur in the bladder, urethra, ureters, or kidneys, preventing urine from flowing and being eliminated.

Urinary tract obstruction is usually caused by kidney stones, which can move through the urinary tract and block urine flow. However, it can also be caused by tumors, blood clots, or scarring from urinary tract surgery.

What to do: Go to the hospital immediately to identify the cause of the obstruction and start the most appropriate treatment. In the case of kidney stones, the nephrologist or urologist may indicate IV pain relievers and, if the stone does not pass, surgery, such as lithotripsy or nephrolithotomy.

3. Uncontrolled diabetes

Uncontrolled diabetes can cause progressive kidney damage due to excess glucose in the blood, which can interfere with kidney function and result in acute kidney injury. According to the CDC, this occurs because high blood sugar can damage blood vessels in the kidneys and reduce how well they filter waste.

What to do: Diabetes treatment should be followed as directed by a primary care provider or endocrinologist to control blood glucose levels and prevent kidney damage. If acute kidney injury occurs, treatment is typically managed in the hospital with a nephrologist.

4. Prostate changes

Prostate changes, such as benign prostatic hyperplasia (BPH) or prostate cancer, can cause urethral obstruction and prevent urine from passing.

What to do: Treatment for BPH (enlarged prostate) is done by a urologist, who may prescribe medication or recommend surgery. In the case of prostate cancer, an oncologist may recommend surgery to remove the prostate, chemotherapy, or radiation therapy, for example.

5. Kidney cancer

Kidney cancer can affect kidney function or cause urinary tract obstruction.

What to do: Treatment for kidney cancer is done by an oncologist and usually involves surgery to remove the affected part of the kidney, radiation therapy, or biologic therapy.

6. Uncontrolled high blood pressure

Long-term uncontrolled high blood pressure can damage the blood vessels in the kidneys, impairing their function and potentially leading to acute kidney injury. According to the CDC, high blood pressure is a major risk factor for chronic kidney disease and can worsen kidney function over time.

What to do: Treatment for high blood pressure should be followed as directed by a primary care provider or cardiologist to help prevent kidney damage. Read more about blood pressure medications your doctor may prescribe.

When acute kidney injury occurs, treatment is typically managed in the hospital by a nephrologist.

Treatment options

Treatment for anuria should be done in the hospital, often with involvement of a nephrologist, urologist, or primary care provider. The goal is to restore urination and treat the underlying cause.

If anuria results from a urinary tract obstruction that blocks urine flow, a surgical procedure may be recommended to relieve the obstruction, restore urine flow, and place a stent.

In cases of kidney failure, hemodialysis is usually recommended because the blood needs to be filtered to prevent the buildup of toxic substances in the body, which could worsen kidney failure.

In more advanced cases, when hemodialysis is no longer fully effective, the doctor may recommend a kidney transplant.

It is also important to continue treatment for the underlying condition, such as diabetes or cardiovascular changes, according to the doctor’s recommendations. This can help prevent complications.