What is Anuria?

Anuria is a word that you can determine the definition of simply by taking its parts and making them a whole. The prefix used, which is “an” or “a” means an absence of something. Urea is a medical term referring to urine. Thus, by putting the two parts of the word together, you can discern that anuria (or anuresis) means a lack of urination.

In a clinical setting, however, this is not precisely the case. Anuria in the medical setting means having an output of urine that is less than 100ml each day. The kidneys have not stopped producing urine completely. When they are completely shut down, the person affected will die.

The term anuria as we know it is used to denote a urine output that is dangerously low. And if it goes untreated, that is when it can lead to death of the patient.

Anuria is usually associated with the word oliguria. This word describes having an output of urine that is less than 500ml per day. Oliguria is one of the early signs of medical problems in the kidneys. Anuria comes much later, when kidney disease has progressed to its advanced state. Anuria is much more serious than oliguria.

Causes of Anuria

  • Prerenal Causes

Prerenal anuria causes refer to problems that are located before the kidneys in the urinary tract. In this case, it refers to the blood vessels that are responsible for supplying the kidneys.

The kidneys are vascular organs, particularly their medullary parts. If there is a low flow of blood to your kidneys, it means that there are other organs also in need of oxygen and blood. Since the kidney is an organ that eliminates waste, it receives even less than the other organs receive.

Prerenal Anuria Causes in Children and Adults

  1. Hypovolemia

This is brought on by and includes:

  • Diarrhea
  • Hemorrhage
  • Burns
  • Vomiting
  • Diuretics
  • Pulmonary edema
  • Fluid loss related to the use of exterior drains
  • Intraoperative loss of fluids
  1. Low systemic vascular resistance

This occurs and has symptoms of:



  • Shock
  • Sepsis
  • Side effects of some drugs
  • Antihypertensive drugs
  1. Heart failure

This includes:

  • Arrhythmia
  • Decreased cardiac output
  • Cardiomyopathy
  • Myocardial infarction
  • Cardiac tamponade
  1. Other causes

They include:

  • Direct renal vein compression
  • Increased pressure in the intra-abdominal area
  • Anaphylaxis
  • Inferior vena cava compression
  • Pancreatitis
  • Diabetes insipidus
  • Diabetes mellitus

In newborn children and infants, there may be additional prerenal causes, including following:

  • Perinatal asphyxia
  • Respiratory distress syndrome
  • Indomethacin
  • Congenital heart disease
  • ACE inhibitors or NSAIDs used by the child’s mother

Renal Causes

These causes refer directly to problems with the kidney. Low output of urine is caused by diseases of the renal tubules and glomerulus.

If there is a presence of tubular and glomerular issues, the kidneys cannot properly and effectively filter your urine. This is why there is a lower output.

Here are some of the renal causes for anuria in adults and children:

  • Endogenous toxins, including myoglobin, hemoglobin and uric acid
  • Nephrotoxic drugs, including:
  • Radiological contrast
  • Cyclosporine
  • Cisplatinum
  • ACE inhibitors that convert angiotensin
  • Penicillin
  • Cephalosporin
  • Some NSAIDs
  • Diuretics
  • Amphotericin B
  • Aminoglycoside
  • Autoimmune diseases
  • Glomerulonephritis
  • Vascular diseases, including vasculitis, renal vein or artery thrombosis or hemolytic uremic syndrome
  • Systemic diseases
  • Family history of renal disease
  • Congenital kidney diseases
  • Hematuria
  • Muscle trauma

Postrenal Causes of Anuria

Postrenal anuria causes affect the structures that come after the kidneys in the urinary tract, like some obstructions to the flow of urine.

If there are not problems with renal disease or renal perfusion, the problem is often urinary obstruction. If your urine can’t pass through the structures as it normally does, there will obviously be less output.

Postrenal causes of anuria include:

  • Benign prostatic hypertrophy
  • Lower urinary tract symptoms (LUTS): dribbling, weak stream or low frequency
  • A urinary bladder mass
  • Calculi
  • Kinks in a catheter (if used)
  • Retroperitoneal fibrosis

In children and newborns, the postrenal causes of anuria include:

  • Issues in the posterior urethral valves
  • Stenosis of urinary meatus
  • Neurogenic bladder
  • Bilateral ureteral obstruction

Anuria Treatments

Cardiopulmonary Resuscitation – CPR

250-500ml of fluid resuscitation may help in increasing the output of urine and in stabilizing blood pressure and heart rate. The goal is for you to develop and hold a 0.5ml/kg/hr. urine output.

The central venous pressure should be maintained at 8-12mmHg with a central venous catheter. An arterial line helps to monitor blood pressure most accurately. If there is a failure in fluid challenge, inotropes will rescue the heart contractions.

Nephrotoxic drugs

If you’re taking drugs that have toxicity to your kidneys, these medications should be discontinued. The obstruction must be released, the intra-abdominal pressure should be decreased, and any underlying infection must be treated.

Hyperkalemia

article-1-pic-1This ECG shows a case of hyperkalemia in the early stages.

Photo Source: http://nswhealth.moodle.com.au

article-1-pic-2This ECG shows a case of progressing hyperkalemia.

Photo Source: http://nswhealth.moodle.com.au

article-1-pic-3This ECG shows a case of hyperkalemia in a later stage.

Photo Source: http://nswhealth.moodle.com.au

Hyperkalemia is considered to be a medical emergency, where the potassium level reaches greater than 6.5 mmol/L and the ECG shows T waves that peak and QRS complexes that are widened. It can also be accompanied by asystole and ventricular arrhythmias.

If hyperkalemia is present, BLS/ALS should be initiated before any other intervention, except CPR. Any infusions of medications containing potassium should be discontinued.

The physician will administer 50ml of glucose 50%; 10ml of calcium gluconate 10% & 10 units of fast-acting insulin. An inhaled beta-2 agonist and 100 mmols of sodium bicarbonate 8.4% will also be given. These drugs help in shifting potassium into cells.

Potassium, however, can still leak from within the cells, so this isn’t a permanent treatment method for hyperkalemia. In order for the symptoms and signs to be eradicated, excess potassium must be excreted from the patient’s body.

In cases of hyperkalemia that are less severe, as in cases where potassium levels are at 5.5-6.5 mmol/L, the potassium will be restricted. 15-30 g of resonium are administered.

Treating Children’s Anuria

Children and infants are more likely to become dehydrated, as compared to adults. If you are caring for an infant or child, you need to be aware of this.

Children’s dehydration is generally treated with 20 ml/kg of fluid bolus of lactated Ringer’s solution or normal saline solution. If there is a case of fluid overload, then diuretic therapy and fluid restriction are ordered. If the cause of this issue is postrenal (stenosis or obstruction), urinary catheterization will be performed.



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