Last reviewed: 25 Sep 2021
Last updated: 13 Jan 2021

Summary

Definition

History and exam

Key diagnostic factors

  • absence of hypovolemia
  • absence of hypervolemia
  • absence of signs of adrenal insufficiency or hypothyroidism
  • nausea
  • vomiting
  • altered mental status
  • headache
  • seizure
  • coma

Other diagnostic factors

  • no history of recent diuretic use

Risk factors

  • age >50 years
  • pulmonary conditions (e.g., pneumonia)
  • nursing home residence
  • postoperative state
  • malignancy
  • medication associated with SIADH induction
  • central nervous system (CNS) disorder
  • endurance exercise

Diagnostic investigations

1st investigations to order

  • serum sodium
  • serum osmolality
  • serum BUN
  • urine osmolality
  • urine sodium

Investigations to consider

  • diagnostic trial with normal saline infusion
  • serum uric acid
  • fractional excretion of sodium
  • fractional excretion of urea
  • serum TSH
  • serum cortisol level
  • serum arginine vasopressin (AVP)

Treatment algorithm

Contributors

Authors

Megan Dixon, MD

Nephrologist

Arizona Kidney Disease and Hypertension Center 

Phoenix

AZ

Disclosures

MD declares that she has no competing interests.

Howard Lien, MD, PhD

Professor Emeritus of Medicine

Division of Nephrology

University of Arizona

Tucson

AZ

Disclosures

HL is an author of a reference cited in this topic.

Peer reviewers

Judith H. Veis, MD

Associate Director

Nephrology

Washington Hospital Center

Washington

DC

Disclosures

JHV declares that she has no competing interests.

Laurie Solomon, MD, FRCP

Consultant Nephrologist

Renal Unit

Lancashire Teaching Hospitals

Fulwood

Preston

UK

Disclosures

LS declares that he has no competing interests.

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