Acute pyelonephritis is a serious bacterial infection affecting the kidneys and the ureter (the tube connecting the kidney to the bladder). In 75 to 90 per cent of cases, it is caused by the bacterium Escherichia coli. It often follows on from acute cystitis that has not been properly treated. Unlike a simple lower urinary tract infection, this condition is relatively serious. It requires prompt treatment to prevent the infection from spreading or damaging the kidney. It is therefore essential to be able to identify the symptoms of pyelonephritis and recognise the early signs.
What are the main symptoms of pyelonephritis in adults?
In young adults, kidney infection often develops suddenly, sometimes following a cystitis that went unnoticed. The symptoms of pyelonephritispresent a very uncomfortable clinical picture involving several warning signs:
- Fever and chills: A sudden rise in body temperature above 38.5°C. This fever is accompanied by intense chills, a sign that the body and the immune system are fighting off the bacterial infection.
- Unilateral lower back pain: This is the hallmark of a kidney infection. It is a sharp pain located in the lower back or abdomen, usually on one side only (as pyelonephritis is predominantly confined to a single kidney). This pain is often aggravated by simple palpation.
- Nausea and vomiting: Digestive problems, sometimes including diarrhoea, frequently accompany the infection. Vomiting is the body’s defensive response to severe inflammation.
- Intense fatigue: Asthenia (persistent abnormal fatigue) is pronounced. The patient feels listless, generally weak and has a constant feeling of being ‘worn out’, even after resting.
What symptoms of pyelonephritis related to urination should you watch out for?
As the infection affects the urinary tract, it directly impacts the act of urination. Medical terminology identifies three major symptoms of pyelonephritis related to urination:
- Dysuria (difficulty urinating): This results from irritation of the urethra or bladder. It manifests as a delay before being able to urinate, a weak stream, or even urinary retention causing a trickle. It is almost always accompanied by an intense and painful burning sensation.
- Pollakiuria (frequent urge to urinate): This is an urgent need to urinate. The bladder muscle (the detrusor) contracts involuntarily, causing an uncontrollable urge to urinate many times during the day, and sometimes even at night, in very small amounts (sometimes every 15 minutes in severe cases).
- Pyuria (cloudy urine): This is the visible presence of pus in the urine, a sign that white blood cells (leukocytes) are fighting the bacteria. The urine becomes cloudy, discoloured and foul-smelling.
Why do the symptoms of pyelonephritis differ between children and older adults?
Diagnosis can be more complex in vulnerable populations, as the symptoms of pyelonephritis are often misleading and atypical:
- In older people: The classic fever may be completely absent. One should be alert to sudden mental confusion, unexplained abdominal pain or a marked deterioration in general health.
- In young children: Warning signs include unexplained fever, crying when urinating, loss of appetite, sudden mood swings (severe irritability), or even unexplained weight loss.
Which symptoms of pyelonephritis warrant emergency medical attention?
Pyelonephritis should always be assessed by a doctor. However, in cases of severe acute pyelonephritis, certain symptomsrequire urgent hospital admission:
- Altered consciousness or severe confusion.
- Extreme weakness (prostration).
- Inability to drink or retain oral medication due to continuous vomiting.
To find out more and continue reading:
- Discover our comprehensive guide: Everything you need to know about acute pyelonephritis, from prevention to natural treatments
- Understanding: diagnosis, the role of urine culture and the causes of infection
Sources:
- https://pubmed.ncbi.nlm.nih.gov/37479904/
- https://www.vidal.fr/maladies/recommandations/pyelonephrite-aigue-de-la-femme-1531.html#prise-en-charge
FAQ: Symptoms of pyelonephritis
What are the first signs of pyelonephritis in adults? The infection usually comes on suddenly. The first signs include a high fever (above 38.5°C) accompanied by chills, severe fatigue, and unilateral lower back pain (a sharp pain on one side of the lower back). Digestive problems such as nausea may also occur.
Is it possible to have pyelonephritis without a fever? Yes, it is entirely possible, particularly in older people. In these patients, the infection may present atypically as sudden mental confusion or abdominal pain. It may also present as a general deterioration in health, without any rise in temperature.
Why is my urine cloudy and foul-smelling? This symptom is called pyuria. It indicates the presence of pus in the urine, which means your white blood cells are actively fighting the spread of bacteria in your urinary tract.
Which symptoms related to the urge to urinate should alarm me? You should watch out for the onset of dysuria (difficulty and intense burning when urinating) and pollakiuria. Pollakiuria manifests as an uncontrollable urge to go to the toilet very frequently, sometimes every 15 minutes, to pass very small amounts.
When do symptoms warrant a visit to A&E? Emergency hospital admission is essential if you or a loved one show serious signs such as: impaired consciousness or severe confusion. You should also seek medical advice in the event of extreme weakness (prostration) or continuous vomiting preventing any hydration or the taking of oral medication.
