Related Experiment Video
Updated: Feb 26, 2026
Intrarenal Injection of Escherichia coli in a Rat Model of Pyelonephritis
Published on: July 18, 2017
Electrolyte and Acid-Base Abnormalities in Infants with Community-Acquired Acute Pyelonephritis: Prospective
Gregorio P Milani1, Angela Grava, Mario G Bianchetti
1Pediatric Unit, Department of Clinical Sciences and Community Health, Ospedale Maggiore Policlinico, Università Degli Studi di Milano, Milan, Italy.
Insights
Infants with acute pyelonephritis frequently experience electrolyte and acid-base imbalances, most commonly hyponatremia. This study highlights the need for accurate laboratory testing in diagnosing these febrile urinary tract infections.
Area of Science:
- Pediatrics
- Nephrology
- Clinical Chemistry
Background:
- Febrile urinary tract infections in infants may be associated with fluid, electrolyte, and acid-base disturbances.
- Previous studies have indicated potential inaccuracies in standard sodium testing methods.
Purpose of the Study:
- To investigate the prevalence of electrolyte and acid-base abnormalities in infants diagnosed with acute pyelonephritis.
- To assess the accuracy of laboratory methods for electrolyte testing in this population.
Main Methods:
- A prospective cross-sectional study of 80 infants (aged 4–24 months) with their first episode of acute pyelonephritis.
- Direct potentiometry was used to measure ionized sodium, potassium, and chloride.
- Bicarbonate levels were calculated from pH and carbon dioxide pressure.
Main Results:
- Electrolyte or acid-base abnormalities were detected in 74% of the infants.
- Hyponatremia was the most common abnormality (54 infants), followed by hypobicarbonatemia (18 infants) and hyperkalemia (14 infants).
- Lower blood tonicity and symptoms like poor fluid intake, regurgitation, or loose stools were more prevalent in infants with abnormalities.
Conclusions:
- Approximately three-quarters of infants with acute pyelonephritis exhibit electrolyte or acid-base abnormalities.
- Hyponatremia is the most frequent finding in this pediatric population.
- Accurate laboratory assessment is crucial for managing infants with febrile urinary tract infections.
Background:
Retrospective case series suggest that abnormalities in fluid, electrolyte, and acid-base homeostasis may occur among infants with a febrile urinary tract infection. Potentially inaccurate laboratory methods of sodium testing have often been used.
Methods:
Between January 2009 and June 2016, we managed 80 previously healthy infants (52 males and 28 females) ≥4 weeks to ≤24 months of age with their first episode of acute pyelonephritis. Ionized sodium, ionized potassium and ionized chloride were determined by direct potentiometry, as recommended by the International Federation of Clinical Chemistry. Bicarbonate was calculated from pH and carbon dioxide pressure.
Results:
Electrolyte or acid-base abnormalities were disclosed in 59 (74%) of the 80 infants: hyponatremia (n = 54), hypobicarbonatemia (n = 18), hyperkalemia (n = 14), hyperbicarbonatemia (n = 6), hypochloremia (n = 3), hypokalemia (n = 3), and hyperchloremia (n = 1). None of the patients was found to be hypernatremic. Patients with and without electrolyte or acid-base abnormalities did not differ with respect to age, sex distribution, and whole blood glucose. Blood tonicity was lower and poor fluid intake, frequent regurgitations or loose stools more common among infants with electrolyte or acid-base abnormalities.
Conclusions:
This prospective cross-sectional study shows that electrolyte or acid-base abnormalities, most frequently hyponatremia, occur in approximately 3 quarters of infants with acute pyelonephritis.
Related Concept Videos
01:28Acute Pyelonephritis II: Diagnostic Studies and Management
01:27Acute Pyelonephritis I: Introduction
01:30Acute Kidney Injury IV: Diagnostic Studies and Prevention
01:29Renal Regulation of Acid-Base Balance
In the kidneys, cells within the proximal convoluted tubules (PCT) and the collecting ducts secrete hydrogen ions (H+) into the tubular fluid. Specifically, in the PCT, Na+/H+ antiporters secrete H+ while reabsorbing Na+.
However, the intercalated cells in...
02:58Bronsted-Lowry Acids and Bases
01:20Acute Kidney Injury V: Interprofessional Care