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Pediatric Metabolic Alkalosis Workup

  • Author: Lennox H Huang, MD, FAAP; Chief Editor: Timothy E Corden, MD  more...
Updated: Jan 03, 2016

Approach Considerations

Measurements of blood gas and serum electrolyte levels, including calcium, are the essential laboratory studies necessary for initial evaluation of metabolic alkalosis. An algorithm for metabolic alkalosis is shown in the image below.

Algorithm for metabolic alkalosis. Algorithm for metabolic alkalosis.

Blood Gas Measurement, Serum Electrolyte levels, and Spot Urine Chloride

Blood gas measurement shows elevated pH with a high HCO3 level. With compensation, the PCO2 level may also be near the reference range or elevated.

Serum electrolyte levels may show evidence of hypokalemia, hypercalcemia, hypochloremia, or hyponatremia.

A urine chloride level of less than 10 mEq/L indicates chloride-responsive metabolic alkalosis. A urine chloride level of more than 20 mEq/L indicates chloride-resistant metabolic alkalosis.


Diagnostic Indicators for Specific Disease States

Patients with primary aldosteronism have metabolic alkalosis, hypokalemia, a urine chloride level of more than 20 mEq/L, and persistently elevated aldosterone levels despite controlled sodium chloride (NaCl) intake of 12-15 g daily for 5 days.

Cushing syndrome is marked by hypersecretion of cortisol.

Primary reninism usually results from renovascular disease with hypertension.

Bartter syndrome manifests as hypokalemic metabolic alkalosis with secondary hyperaldosteronism and with renal potassium and chloride wasting.

Milk-alkali syndrome results from excessive oral intake of calcium, vitamin D metabolites, and absorbable alkali. Metabolic alkalosis in these patients is usually accompanied by hypercalcemia.

Pyloric stenosis causes marked hypochloremia (due to loss of HCl in gastric contents) and metabolic alkalosis. It is generally observed in male infants aged approximately 6-12 weeks. These patients present with protracted vomiting and frequently have significant dehydration and cachexia.

Contributor Information and Disclosures

Lennox H Huang, MD, FAAP Associate Professor and Chair, Department of Pediatrics, McMaster University School of Medicine; Chief of Pediatrics, McMaster Children's Hospital

Lennox H Huang, MD, FAAP is a member of the following medical societies: American Academy of Pediatrics, American Association for Physician Leadership, Canadian Medical Association, Ontario Medical Association, Society of Critical Care Medicine

Disclosure: Nothing to disclose.


Margaret A Priestley, MD Associate Professor of Clinical Anesthesiology and Critical Care, Perelman School of Medicine at the University of Pennsylvania; Clinical Director, Pediatric Intensive Care Unit, The Children's Hospital of Philadelphia

Margaret A Priestley, MD is a member of the following medical societies: American Academy of Pediatrics, American Medical Association, Society of Critical Care Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Barry J Evans, MD Assistant Professor of Pediatrics, Temple University Medical School; Director of Pediatric Critical Care and Pulmonology, Associate Chair for Pediatric Education, Temple University Children's Medical Center

Barry J Evans, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Chest Physicians, American Thoracic Society, Society of Critical Care Medicine

Disclosure: Nothing to disclose.

Chief Editor

Timothy E Corden, MD Associate Professor of Pediatrics, Co-Director, Policy Core, Injury Research Center, Medical College of Wisconsin; Associate Director, PICU, Children's Hospital of Wisconsin

Timothy E Corden, MD is a member of the following medical societies: American Academy of Pediatrics, Phi Beta Kappa, Society of Critical Care Medicine, Wisconsin Medical Society

Disclosure: Nothing to disclose.

Additional Contributors

G Patricia Cantwell, MD, FCCM Professor of Clinical Pediatrics, Chief, Division of Pediatric Critical Care Medicine, University of Miami Leonard M Miller School of Medicine/ Holtz Children's Hospital, Jackson Memorial Medical Center; Medical Director, Palliative Care Team, Holtz Children's Hospital; Medical Manager, FEMA, South Florida Urban Search and Rescue, Task Force 2

G Patricia Cantwell, MD, FCCM is a member of the following medical societies: American Academy of Hospice and Palliative Medicine, American Academy of Pediatrics, American Heart Association, American Trauma Society, National Association of EMS Physicians, Society of Critical Care Medicine, Wilderness Medical Society

Disclosure: Nothing to disclose.

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Algorithm for metabolic alkalosis.
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