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Hypokalemia: Differential Diagnoses & Workup

Author: Michael J Verive, MD, Medical Director, Pediatric Intensive Care, Department of Pediatrics, St Mary's Hospital for Women and Children
Contributor Information and Disclosures

Updated: Sep 21, 2009

Differential Diagnoses

Hyperthyroidism

Other Problems to Be Considered

Pseudohypokalemia may be seen with sampling errors, particularly if a blood sample is taken upstream of an infusion of saline, dextrose, or other fluids that contain little or no potassium. Clues to sampling errors include other serum level abnormalities that reflect sampling of a mixture of blood and the fluid that is infused.

Workup

Laboratory Studies

The following studies are indicated in patients with hypokalemia:

  • Serum electrolyte tests: Screen for concurrent electrolyte abnormalities, which may affect treatment.
  • Blood gas analysis
    • Assess acid-base status.
    • Alkalosis may induce hypokalemia, and treatment of acidosis may worsen existing hypokalemia.
  • Drug screen (serum or urine)
    • Amphetamines and other sympathomimetic stimulants can cause hypokalemia.
    • Other drugs that can cause hypokalemia include verapamil (with overdose), theophylline, amphotericin B, aminoglycosides, and cisplatin.
  • Serum adrenocorticotropic hormone (ACTH), cortisol, renin activity, and aldosterone tests: Evaluate for suspected Cushing, Conn, or adrenal hyperplasia syndromes, including 11-beta-hydroxylase deficiency.
  • Simultaneous serum insulin and C-peptide tests: Because hyperinsulinism can cause transient hypokalemia, elevated serum insulin without appropriately elevated C-peptide suggests exogenous insulin administration, which may represent Münchhausen-by-proxy syndrome.

Imaging Studies

  • MRI: Perform brain MRI if a brain or pituitary tumor is suspected as a cause of hypercortisolism.
  • Ultrasonography and CT scanning: Perform abdominal ultrasonography or CT scanning if an adrenal tumor or hyperplasia is suspected.

Other Tests

  • Although ECG changes may be helpful if present, their absence should not be taken as reassurance of normal cardiac conduction.4
  • The ECG in hypokalemia may appear normal or may have only subtle findings immediately before clinically significant dysrhythmias.
  • ECG findings may include the following:
    • Ventricular dysrhythmia
    • Prolongation of QT interval
    • ST-segment depression
    • T-wave flattening
    • Appearance of U waves
  • During therapy, monitor for changes associated with overcorrection and hyperkalemia, including a prolonged QRS, peaked T waves, bradyarrhythmia, sinus node dysfunction, and asystole.

More on Hypokalemia

Overview: Hypokalemia
Differential Diagnoses & Workup: Hypokalemia
Treatment & Medication: Hypokalemia
Follow-up: Hypokalemia
Multimedia: Hypokalemia
References
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References

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  2. Kumar PS, Deenadayalan M, Janakiraman L, Vijayakumar M. Neonatal Bartter syndrome. Indian Pediatr. Aug 2006;43(8):735-7. [Medline].

  3. Johns C. Glycyrrhizic acid toxicity caused by consumption of licorice candy cigars. CJEM. Jan 2009;11(1):94-6. [Medline].

  4. [Guideline] Drew BJ, Califf RM, Funk M, et al. Practice standards for electrocardiographic monitoring in hospital settings: an American Heart Association scientific statement from the Councils on Cardiovascular Nursing, Clinical Cardiology, and Cardiovascular Disease in the Young: endorsed by the International Society of Computerized Electrocardiology and the American Association of Critical-Care Nurses. Circulation. Oct 26 2004;110(17):2721-46. [Medline].

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  6. Dinleyici EC, Dogruel N, Acikalin MF, Tokar B, Oztelcan B, Ilhan H. An additional child case of an aldosterone-producing adenoma with an atypical presentation of peripheral paralysis due to hypokalemia. J Endocrinol Invest. Nov 2007;30(10):870-2. [Medline].

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  13. Parr JR, Salama A, Sebire P. A survey of consultant practice: intravenous salbutamol or aminophylline for acute severe childhood asthma and awareness of potential hypokalaemia. Eur J Pediatr. May 2006;165(5):323-5. [Medline].

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  15. Rose BD. Introduction to disorders of potassium balance. In: Clinical Physiology of Acid-Base and Electrolyte Disorders. 1989:715-56.

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Further Reading

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Keywords

hypokalemia, potassium deficiency, vomiting, dialysis, diarrhea, diuretics, alkalosis, insulin, catecholamines, sympathomimetics, hypothermia, renal tube disorders, distal renal tubular acidosis, Bartter syndrome, Gitelman syndrome, periodic hypokalemic paralysis, hyperthyroidism, beta2-adrenergic agents, hyperaldosteronism, cystic fibrosis, Cushing syndrome, exogenous steroid administration, GI hypomotility, GI ileus, cardiac dysrhythmia, QT prolongation, muscle weakness, muscle cramping, hypomagnesemia, hyperhidrosis, diabetic ketoacidosis, acute myelogenous leukemia, monomyeloblastic leukemia, lymphoblastic leukemia

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Contributor Information and Disclosures

Author

Michael J Verive, MD, Medical Director, Pediatric Intensive Care, Department of Pediatrics, St Mary's Hospital for Women and Children
Michael J Verive, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Chest Physicians, and Society of Critical Care Medicine
Disclosure: Nothing to disclose.

Medical Editor

G Patricia Cantwell, MD, Associate Clinical Professor, Department of Pediatrics, University of Miami; Director of Pediatric Critical Care Medicine, Miller School of Medicine, Jackson Children's Hospital
G Patricia Cantwell, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Emergency Physicians, American Heart Association, American Trauma Society, National Association of EMS Physicians, Society of Critical Care Medicine, and Wilderness Medical Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from financial planner; Avanir Pharma Stock Investment from financial planner ; WebMD Salary and stock Employment and investment from financial planner

Managing Editor

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, and Society of Critical Care Medicine
Disclosure: Nothing to disclose.

CME Editor

Mary E Cataletto, MD, Associate Director, Division of Pediatric Pulmonology, Winthrop University Hospital; Professor of Clinical Pediatrics, State University of New York at Stony Brook; Director of Children's Sleep Services, Winthrop University Hospital
Mary E Cataletto, MD is a member of the following medical societies: American Academy of Pediatrics and American College of Chest Physicians
Disclosure: Shering Plough Pharmaceuticals Honoraria Consulting

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, and Wisconsin Medical Society
Disclosure: Nothing to disclose.

 
 
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